This Brilliant Man Can Get You In Trouble – Misapply MacCready Theory At Your Own Peril

(Editorial Note: since initial publication, I have added a few thoughts suggested by readers.  Andy Blackburn’s input has been particularly valuable.  I also added a post scriptum at the end with additional tips.  Thank you to all who commented.)

Who has not heard of the MacCready Speed-To-Fly Theory?  It is the brilliant discovery of a brilliant man who was not only the first American to become a world soaring champion but who came up with a scientific way to demonstrate how fast we should be flying in-between thermals in order to maximize our cross-country speed.

Paul MacCready (1925-2007) – one of the most most influential individuals in soaring history. You can find his bio here.

Not long after MacCready published his theory, other pilots followed his example and began equipping their gliders with “MacCready Rings”.  These are simple devices mounted around a glider’s variometer telling  the pilot how fast they should be flying depending on the expected strength of the next lift.

With the onset of flight computers, MacCready’s Speed-To-Fly Theory (or STF for short) went digital.  Today, every flight computer requires the pilot to input their “MC value”,  and every STF vario will produce audio and visual signals. These tell the pilot whether to speed up, slow down, or maintain the current speed – based on the MC value they selected.

Over time the application of STF theory has evolved a bit.  E.g., pilots have learned that it is useful to slow down as they get closer to the ground to minimize the risk of a landout.  Others correctly pointed out that “chasing the needle” is not only distracting but that constant control inputs make it inefficient as well. Instead, most would recommend flying at “block speeds” that approximately correspond to the correct MC setting.  After all, flying a bit too slow or a bit too fast makes little difference in terms of the average speed achieved. Some have even come up with scientific ways to show when, how, and how much to deviate from MacCready’s theory. (E.g., see Daniel Sazhin’s and John Bird’s work about “Bounded Rationality and Risk Strategy in Thermal Soaring” or John Cochrane’s article, “MacCready Theory with Uncertain Lift and Limited Altitude“).  Instead of getting into more details here, I recommend that interested readers take a look at the article “Just a Little Faster, Please“, also by John Cochrane.

However, no-one doubts that MacCready theory at its core is mathematically correct and scientifically sound.  It remains the undisputed foundation of any theory about how fast we should fly in cruise.  Most importantly: every flight computer and every vario asks you to input an MC value.  So you better know what these devices are doing with the information you enter.

MacCready Theory in a Nutshell

Every soaring textbook has an explanation for how and why the theory works. In essence, it is quite simple: when the lift ahead promises to be strong you should fly faster.  When the lift ahead looks to be weaker, you should fly closer to your glider’s best L/D speed, i.e. the speed where it has its best glide ratio.  MC theory tells you exactly how fast you should fly based on the strength of lift you expect ahead.

The series of charts below illustrate a simple example.  They are based on the speed polar of a Discus CS (one of the most popular standard class gliders) without water ballast.  (The principles explained are the same for whatever glider you fly but the values will obviously differ. If you fly a similar glider, such as an LS4, a DG 300, or an ASW 24 they will be close. A DG 505’s polar is also similar.) The speed polar is the curved line in blue.  It illustrates the rate of sink at various speeds.  The speeds are on the horizontal axis (in kts), and the glider’s rate of sink at these speeds is shown on the vertical axis (also in kts).  Using the same units on both axes (in this case kts) is very helpful because you can calculate the glide ratio at any point along the curve simply by contrasting the speed to the sink rate.

Speed polar of a Discus CS. Horizontal and vertical speeds are in knots (nautical miles per hour).

The next graph below shows that the best glide performance of the Discus CS is at about 55 kts. You can find this best glide speed by placing a tangent (the red line) against the speed polar starting at the chart’s origin (the point 0,0).

The best L/D speed is at the point where a tangent originating at 0,0 touches the speed polar.

At 55 kts the Discus will sink at a rate of 1.3 kts.  55 divided by 1.3 equals 42.  55 kts is the best L/D speed for a Discus and its best glide ratio is 42:1.

The only time you would ever fly at the best glide speed is when you are desperate.  Let’s say the lift has died for the day, the air is completely still, and you are just high enough to safely make it to an airport.  That’s when you would fly at best L/D.  This speed is also called MC 0 speed:  the expected strength of the next lift is zero (because you know there is no more lift to be had) and all you are trying to do is to stretch your glide as far as possible.

Let’s look at a more frequent example.  It’s a pretty strong day.  You are high and there are several good-looking cumulus clouds ahead. During the last few climbs you achieved 4-5 knots on average from the bottom to the top of each thermal (including any centering delays, re-centering efforts, etc) and you expect the next lift will be just as strong.  In this case it makes sense to set your MC to 4.  You expect the next lift to be just as strong and you are not willing to stop for anything less than that – at least for now.  In this case you should fly at MC 4.  (MC 3 or MC4 are perhaps the most common MC settings that pilots use for Speed-to-Fly calculations.  Higher settings only make sense in exceptionally strong conditions. How often would you not take a climb that averages 4+ knots from bottom to top?)

You simply feed MC 4 into your vario and it will tell you to fly at MC 4 speed.  The chart below shows you how your vario calculates this speed:  it places a tangent (once again the red line) along the speed polar curve but this time it starts at a point 4 knots above the origin.  The tangent touches the speed polar at 83 kts and you can see that at this speed the glider will sink 2.9 kts per hour.  The glide ratio at this speed is 83/2.9 = 29.  I.e. you will glide 29 ft forward for every 1 ft of altitude you lose.  29:1.

At MC 4, a Discus will achieve the highest average speed if you fly at 83 kts in still air. At this speed your glider will descend by 2.9 kts and your effective glide ratio will be 29:1.

OK, so far, so good.  You already knew this anyway.  But what does this have to do with the headline?  Where’s the peril?  That’s what we’re getting to now.

The Other Use of the MacCready Value

The MC value that you enter is not only used by your vario to calculate your best Speed To Fly but it is also used by your flight computer to calculate whether you can safely reach a place to land.

I very much doubt that this was Paul MacCready’s idea.  But that’s how your flight computer works. And if you don’t know it, it can be a big problem!

In the example we just discussed above it is hard to see.  When you’re flying high and happy and are confident that the next thermal will deliver a 4 kt average climb you are probably not too concerned about reaching a safe place to land.  And if you glance at your flight computer it will use your MC 4 setting to calculate which airports (or landout fields) are in safe glide at MC 4.  I.e., it will do so based on a glide ratio of 29:1.

But let’s say the expected 4 kts of lift did not materialize.  In fact, the clouds that looked so good before are now dissolving and you’re getting lower and lower.  Far from being confident that the next lift will deliver 4 kts, you are gradually getting concerned.  And, as you should, you dial back your MC settings.  First to MC 3, then to MC 2, and, as you get lower and lower, you move it back to MC 1. Eventually you are getting desperate and dial it all the way back to MC 0.

This makes sense because you want your STF vario to tell you to fly more slowly so you better conserve altitude and have more options to find lift ahead, rather than driving hard down to the ground.

But what does your flight computer do with the same information?  As you reduce your MC settings to 3, 2, 1 and then to 0, your glide computer thinks you can glide farther and farther.  It basically removes your safety margin.  Remember: at MC 0 your flight computer believes you are able to consistently  fly at the very optimal glide speed – 55 kts in still air – and achieve a glide ratio of 42:1. Is this realistic? Probably not.

By reducing the MC value to 0 you just told the glide computer to lie to you.  It is now showing airports (or fields) in glide range that really aren’t.

But things are probably even worse.  Quite possibly much worse!

Unless the day has truly died and the air become completely still, chances are that the airmass you are flying through is actually going down.  Why?  Because as long as there are thermals and the air is going up somewhere, it must be going down elsewhere.  Completely still air hardly ever exists and it most definitely does not exist on a day when we expect to find enough lift to fly cross-country.

So let’s say the air you’re flying through is actually going down by 1 kt.  One knot is not much and definitely not unusual. What are the implications?

Well, first of all you should be flying a bit faster.  When the air is sinking at 1 kt, your STF vario will tell you to speed up even if you leave your MC setting at 0.  How does it do this?  Easy: 1 kt sink will simply shift the glide polar down by 1 kt because you have to add the sink rate of the airmass to the sink rate of the glider.  (The vario obviously knows you are in sink and it does this automatically. ) You can see the new polar on the chart below (in orange).  You can also see where the tangent touches the new polar curve.  This point is at 59 kts and your sink rate will now be 2.4 kts.  (In still air it would be 1.4 kts but since you’re in 1 kt sink, so you’re actually coming down at 2.4 kts.)

Sink will shift the speed polar down because the sink rate of the air must be aded to the sink rate of the glider at any given speed.

Now, look at what happened to the glide ratio!  At 59 kts and 2.4 kts sink, your glide ratio is now 59/2.4 = 24:1.   You’re still flying a high performance glider but just 1 kt of sink is enough to basically turn it into a Schweitzer 1-26!

What about the safety glide calculation?  Your glide computer does not know how long the sink will last so it does not take it into account at all!  (This makes sense because otherwise the safety glide calculation would jump around wildly each time you fly through a bit of lift or sink.) Remember this! The flight computer will account for wind (because wind doesn’t change from second to second) but it does not account for lift or sink when it calculates which airports (or fields) are in glide.

So what does it tell you?  Since you turned down the MC value to 0, it will calculate your safety glide with a 42:1 glide ratio even though you are only achieving 24:1!

It is easy to see why this is at best misleading, and at worst a major safety hazard.  A lot of beginning XC pilots tend to use what they think of as a “conservative”, i.e. low, MC setting.  As long as this is only applied to Speed-to-Fly calculations it makes sense because it helps them stay high (while obviously slowing them down).  But when applied to safety calculations a “low” MC setting is just the very opposite of conservative!

What Should You Do?

Now that you understand that your MC settings are used for two completely different purposes – calculating your speed to fly, and calculating your safety glides – what can you do about it?

The answer is simple: use two different MC settings, each appropriate for its purpose!

If your glider has an electronic Speed-to-Fly vario and you are also using a completely separate flight computer with a moving map, things are straightforward. For the vario use an MC setting that’s based on the minimum strength of the lift you are willing to accept.  For the flight computer use an MC setting that’s appropriate for safety glide calculations.

This describes the setup that I was flying with last year.  I had an STF vario in the panel and a stand-alone Oudie IGC flight computer with a moving map display.  I entered my STF MC setting into the vario, and kept a different (usually higher) MC setting on the Oudie.  This way the Oudie would only show me airports and fields that really were in safe glide range.

Things get problematic when your STF vario and your flight computer are connected with one another. Changes that you make to your MC settings on one device are probably automatically sent to the other device. The two devices are kept in synch.  This seems like a great convenience but in reality it is anything but!  In real life it is quite rare that you want to use the same MC value for your STF calculations and for your safety glide calculations. And whenever it is appropriate to use two different values than either of these two calculations will simply be wrong!

If you use a setup where your SFT vario and your flight computer are connected with one another (e.g. via cable or bluetooth), see if there is a setting that prevents the two devices from synchronizing MC values.  You want each of these devices to correctly calculate the thing it is supposed to calculate!

If you only use only one single device for both STF and safety glide calculations (or if you cannot prevent your STF vario and your flight computer from synchronizing MC values) you must remember to edit your MC setting based on what you want to focus on. If you are relatively new to cross country soaring I suggest that you set the MC value appropriately for safety calculations and simply ignore your vario’s speed-to-fly suggestions.  You’re probably not going to fly as fast anyway as the vario suggests you should.

And there’s one additional thing you should do:  make sure that you complement a safe glide calculation by also setting a safe arrival altitude.  After all, you don’t want to arrive at the airport (or field) at grass root level. You want to have enough time to do a proper landing check and fly a safe landing pattern.  What’s a safe arrival altitude?  That is a different question for another time.  In Boulder, I always plan to arrive no lower than 1500 AGL because we have a very busy airport, and I may be in line behind other gliders or even a bunch of skydivers that are floating above the field just when I get there. Extreme weather can create problems, too.  Here’s a scary experience from a few years ago.

What MC Value is Appropriate for Safety Glide Calculations?

We know from the MacCready theory how to set MC for Speed-to-Fly calculations:  enter the expected lift of the next thermal.  Better still (since you don’t really know how strong the lift ahead will be): enter the minimum strength of lift that you are willing to take right now.

But how to set MC for calculating safety glides?  Well, as always, it depends. Since this calculation is about safety, and only about safety, the key question you should ask:  given the looks of the conditions ahead, what is the “worst-case glide slope” with your glider in the direction you’re heading – at least until the next landable field or airport?  Whatever your estimate is, you can then enter an MC value that corresponds to that glide slope.

OK, so how do you estimate your worst-case glide slope?

We have seen above that sink has a very negative impact on the attainable glide slope.  Just 1 knot of sink will turn a 1:42 glider into a 1:24 glider.  What about 2 knots of sink?   Let’s take another look at the speed polar.

Discus glide polar in still air (blue) and glide polar in 2 kts of sink (orange). If the air descends at 2 knots the best attainable glide ratio is 18:1. To achieve it, the pilot must fly 67 kts.

Two knots of sink will shift the speed polar down by – you guessed it – 2 knots.  You’re in sink, so you must fly faster.  How fast? Place a tangent from the origin against the new (orange) speed polar.  67 knots is the speed to fly and your rate of sink will be 3.8 kts.  In the best case, this equates to a glide ratio of 18:1.  (I say best case because it is pretty difficult to fly exactly at the right speed to fly and if you fly a little faster or slower, your glide ratio will actually be worse than 18:1.)

Depending on where you fly, two knots of sink still isn’t all that bad.  Here in Colorado it is not uncommon to hit pockets of sink where the air goes down by 5 kts or even 10 kts.  In wave conditions it could be as much as 20 kts!  How would that affect your glide slope?

The chart shows the original polar curve (in blue), as well as three additional polar curves: one for 5 kts of sink (orange), one for 10 kts of sink (gray), and one for 20 kts of sink (yellow). Tangents from the origin against each of these polar curves determine the best achievable glide slope at the indicated flying speeds. The point where the tangent would touch the curve for 20 kts of sink is to the right of the chart. Va and VnE also set practical limits how fast you can fly to get out of such extreme sink.

The chart above shows that the impact of strong sink is downright frightening.  If you fly through 5 kts of sink your best glide ratio is 11:1 at a speed of 88 kts.  If you cross 10 kts of sink, your best glide ratio becomes 5:1 at a speed of 102 kts.  And at 20 kts of sink, the answer is literally off the chart. You’d fly somewhere between rough air speed and Vne and you’d be lucky to achieve much better than 2:1.

Scared? Well, you should be.  Big sink is scary.  If feels like you’re coming down like a brick.  Because you are. Well, almost.  Fortunately, strong sink tends to be short-lived.  And since it’s true that what goes up must come down, it’s also true that what comes down must go up.  Strong sink and strong lift tend to exist in close proximity to one another.  Wave flying is an extreme example where 10-20 kt lift and 10-20 kt sink can be within 1 or 2 miles from one another.  Try to get out of sink and back into lift as soon as possible! Hopefully you know what you’re doing!  Or, perhaps even better: think twice before you decide to fly in such extreme conditions to begin with.  The point is that such extreme scenarios are not really all that helpful when you decide how to program your flight computer.

In regular summer soaring conditions the more typical cases are that you’re getting low because the lift is weakening, that you fell out of the lift band, or that you crossed into a slowly descending airmass.  In Boulder, Colorado, a classic example for the latter is that you fell out of the convergence, can’t get back, and are struggling to find good lift in the eastern airmass. A divergence zone running parallel to the convergence may put you in sink.  In these cases you are unlikely to be confronted with sustained strong sink.  But even in relatively benign conditions, it is still quite possible that you experience an average of 1 kt of sink on your final glide home.

Lets revisit the chart for 1 knot sink.

As we saw before, at 1 kt sink we should fly 59 kts and our glider will sink at a rate of 2.4 kts.  Our glide ratio will be 24:1.

If this is the “worst-case glide-slope” that we are expecting, how can we instruct our flight computer to make the appropriate safety calculation?  The answer is: we have to find the MC setting that corresponds to a 24:1 glide slope in the absence of lift or sink.

The following chart shows how we can do this easily.

This chart is identical to the one above except that he additional intersection point of the 24:1 glide ratio line and the still-air polar curve is highlighted. Note that 90/3.7 obviously also equals 24:1.


We simply look for the point where the 24:1 glide slope line (i.e. the red tangent to the orange speed polar) intersects the original (blue) still-air speed polar.  We find that this point is at a speed of 90 kts and a sink rate of 3.7 kts.  Now we draw a new tangent (the dotted red line) that touches the blue polar at exactly this spot. Then we check where this new tangent intersects the vertical axis. You can see that for the Discus this point is at 6 kts.  In other words: if we expect a worst case glide slope of 24:1 all the way to the airport (i.e., conditions that reflect 1 kt of sink), we should set MC to 6.

You might be interested what MC setting I use.  Once again, it depends!  If there is a well-marked energy line ahead that I can follow, e.g. a cloud street or the typical Rocky Mountains convergence line, I am comfortable to base my safety glide ratio on an MC value as low as 3.  If the sky is blue and I don’t really know what to expect I tend to use MC 4 or 5.  And if the terrain is particularly hostile I bump it up to 6 or 7. Ultimately, it comes down to a judgement call.  The more doubt I have about the conditions ahead and the greater the probability of sink, especially prolonged sink, the higher I set my MC value.

If you’re flying in particularly challenging terrain or if you’re not yet experienced in avoiding areas of persistent sink, you may want to follow the advice of the French mountain soaring team and use a “worst-case glide ratio” that is 1/2 of your gliders best glide performance. For the Discus CS this glide ratio is 21:1.  The chart below shows that a Discus (without water ballast) will achieve 21:1 at a speed of 95 kts when the corresponding sink rate is 4.5 kts.  And the corresponding MC value is about 10.

At tangent placed against the point where the glide ratio line of 21:1 intersects the blue polar curve crosses the vertical axis at +10. In real life you will probably never expect the next climb to average 10 kts from bottom to top, but if you did, you would fly a dry Discus at 95 kts, i.e., MC 10.

Remember that estimating a “worst-case glide ratio” is by no means a guarantee that reality may not be harsher yet.  Perhaps even much harsher.  I have shown above how bad a glide ratio gets if you hit 5, 10, or even 20 knots of sink!


The purpose of this article was to make clear that your glider avionics use MC for two completely different purposes and that applying inappropriate values can have dangerous unintended consequences.

Your STF vario uses MC to calculate the best speed-to-fly based on your assessment of the strength of lift ahead.  If you’re conservative, you want this value to be lower, not higher.  This will make you stay relatively high albeit at the expense of a somewhat lower cross-country speed. Irrespective of your level of experience, the most appropriate MC value is, “what is the weakest lift that I would be willing to accept right now.” MC 2, 3 or 4 are fairly typical.  Only in exceptionally strong conditions will it be 5 or higher.

Your moving map flight computer uses MC to calculate which airports or fields are within safe gliding distance.  If you’re conservative, you want this value to be higher, not lower.  This will force you to stay high enough that you can safely reach your destination even if you should face less than favorable conditions ahead. Your skills, experience, the terrain, and the conditions of the day are all important factors to consider when you set this value.  On benign summer days a value of MC 5 or 6 may be appropriate.  If you’re inexperienced, flying over hostile terrain, or if you are unfamiliar with a particular soaring area, MC 10 will give you an extra safety margin. And always complement your glide slope calculation with a safe arrival altitude so you have the altitude you need for a safe landing pattern.

Importantly, set your MC values separately for  your STF vario and your flight computer.  Prevent these devices from synching their respective MC values if at all possible.  Be very careful if you only use one device (or one synchronized input) for both calculations.  The biggest trap exists when you dial back your MC setting for SFT purposes and your flight computer stretches your attainable glide unrealistically farther and farther.

Even the highest possible MC setting will not be appropriate to calculate safety glides when extreme sink, or strong sustained sink, is possible. When conditions are extreme, the best advice is to stay really high at all times.  And if that’s not possible, or if you’re not sure you can deal with the conditions at the time, you can always decide to fly on a different day instead.

Have fun and fly safe!


Post Scriptum

There has been a lot of interest in this article.  Within 48 hours of publication it has been read about 2,500 times and a lot of readers made excellent comments, either below or on social media.

First of all they confirm that the trap is real: entering a low MC value into your flight computer will result in wildly over-optimistic glide slope calculations and show fields or airports within glide range that really are not. However, there are multiple ways to avoid the trap and my suggestion in the article of using a different (and higher) MC value for safety glide slope calculations is only one of them.

Below I want to summarize a few comments that I found particularly helpful:

  • If the terrain in your soaring area is generally landable there is not all that much to be concerned about.  E.g., one pilot from the Netherlands commented that where he flies there are always several landable fields in glide even from as low as 1000 AGL.  If that describes your soaring terrain then this topic doesn’t really apply to you.  Your main challenge may be to resist the temptation to keep trying to find lift until you’re very close to the ground.  Delaying the decision to land until it is too late for a safe landing is the #1 reason why glider pilots get killed. This is a different topic. You can read more about it here.
  • As an alternative to using MC inputs for your final glide calculation you may be able to use “Required L/D”.  E.g., I have my Oudie set up to display two Nav boxes at the top of the screen: “Required L/D” and “Current L/D”.  As long as my “Current L/D” exceeds the “Required L/D” I am gaining relative to my required glide slope and my odds of making it to the target improve.  Conversely, if the “Current L/D” drops below the “Required L/D” I am losing against my required glide slope and may be in trouble.  This is a very useful method.  If you use it, it is critical that you also complement it with a safe arrival altitude. In this video, I show an example of a final glide back to Nephi, Utah where I needed a glide ratio of 25:1 to get back to Nephi but then my “Current L/D” temporarily dropped to 18:1.  (I was flying my 48:1 Ventus 2.)
  • A lot of excellent pilots don’t use a “Speed-to-Fly” vario to tell them how fast to go.  Instead they primarily rely on “block speeds.”  E.g., if they are high and feel “confident” of finding good lift they will fly at a speed that roughly corresponds to their gliders STF at an MC setting of 4 in still air.  If they are getting towards the bottom of the best lift band they become “conservative” and fly at a speed that corresponds to MC 2.  And when they get “desperate” and are really looking for lift, they slow down to a speed corresponding to MC 1. And if they are “feeling lucky” high under a strong cloud street they fly extra fast.  One of the commenters calls it “warp” speed.  For a dry Discus CS these speeds might be: desperate: 60 kts; conservative: 65 kts; confident: 75kts; warp: ~85-90 kts.  Add about 10 kts to each speed when flying with water ballast.  If you like this method there is no need to mess with your MC value at all.  Simply set an MC value on your flight computer that’s appropriate for your safety glides (combined with a safe arrival altitude) and leave it at that.
  • Similarly, if you like your STF vario set to “netto” instead of “Speed-to-Fly” you also don’t need to bother meddling with MC values during the flight, and can just use an appropriate MC setting for safety glides on the flight computer.
  • What MC value is appropriate for safety glides varies with the soaring terrain.  My article was written from a mountain flying perspective.  Where I fly in Colorado it is common that the next landable airport or field is 20, 30, 40, or even 50 miles away and soaring conditions tend to include strong lift as well as strong sink.  Talk to experienced pilots in your area to understand what safety glide ratio (and hence what MC value) may be appropriate for where you fly.

Keep the comments and insights coming.  Soaring is an unforgiving sport and our safety largely depends on our ability to learn from the mistakes others have made before us.  (Or on sheer luck – but only for as long as it lasts.)  By learning together we’ll become better and safer pilots.

My Soaring Goals for 2021

Soaring above Mount of the Holy Cross – one of the more intimidating 14ers in Colorado

Having reviewed my progress against the Soaring Goals that I had set for 2020, the last day of the year feels like a good time to publish new goals for 2021.

So here’s what I’m aiming for:

1. Stay Safe by always heeding my own advice.

2. Improve Specific Flying Skills, based on this analysis of a race day in Nephi, this analysis of the Speed League Season, and the advice from soaring GOAT Sebastian Kawa, who emphasized that we must learn to fly very precisely if we want to be fast.

      • Netto in cruise.  Sharpen focus on following energy lines, measured by consistently achieving above-average netto values in cruise flight, a much better metric than circling percentage and effective glide ratio.
      • Altitude band.  Use more of the available altitude band to become more selective in thermal acceptance.  This will require an adjustment of my flying style.
      • Precision thermalling. Focus on quick centering, maintaining optimal coordination, circling speed, and 45 degree bank angles.  As a result, achieve above average climb rates when compared to other pilots flying in the same area on the same day.

3. Speed Goals. Apply these skills to achieve the following:

      • When flying on Speed League Weekends aim to score among the top 3 Boulder pilots 66% of the time (up from 50% in 2020).
      • Try to break one of the Open Class Colorado Speed Records (stretch goal).

4. Distance Goals.  Weather permitting, I would like to achieve two of the following in 2021:

      • Reach one additional U.S. State flying from Boulder: New Mexico, Utah, or Nebraska.  An aspirational stretch goal is a “border to border” flight from Boulder to New Mexico, then to Wyoming, and back to Boulder.
      • Complete a 1000 km flight per OLC plus rules.
      • Complete a 750 km FAI triangle or a 1000 km Diplome.
      • Add to my 14er bag with a flight to the southern-most peaks of the Sangre de Cristo Range or a flight into the San Juan Mountains.

5. Contest Goals.  I plan to fly at least three or the following four contests:

      • Region 7 in Albert Lea, MN (May 17-22)
      • 20m 2-seater Nationals in Montague , CA (Jun 14-22)
      • Region 9 or 18m Nationals in Nephi, UT (Jun 29 – Jul 8)
      • Region 10 in Uvalde, TX (Aug 15-21)

Since these are my first contests, I want to focus mainly on skill development, flying consistently, and completing as many tasks as safely possible.  Stretch Goal: place in the top 33% at one of the Regional Contests or in the top 50% at a Nationals Contest.

6. Giving Back.  I will continue to put energy towards inspiring others worldwide to join our sport, to develop, excel, and stay safe.  I will do this through:

      • Writing – follow me on and on Facebook
      • Presentations and Podcast Contributions – to local, national, and international audiences
      • Videos – subscribe to my ChessInTheAir YouTubeChannel, and
      • Serving for soaring organizations such as the Soaring Society of Boulder

I wish everyone a Very Happy New Year!

Stay safe, and may your soaring goals come to fruition.


Was 2020 A Pandemic Write Off? Not So Fast!

This time last year I was in the midst of negotiating the purchase of my first glider: a beautiful Ventus 2cxT.  It was “almost like new” with only 500 hours.  Early in January I closed the deal and drove to Dallas, Texas for a final inspection. Having found that everything was indeed tiptop, I was excited to tow it home to Colorado.

In February I travelled to the SSA convention in Little Rock, Arkansas.  Attending seminars and seeing all the shiny new objects on the convention floor I was excited for the soaring year ahead.  I also met with Daniel Sazhin, multiple US National Champion, who was kind enough to brief me on soaring in Montague, CA and Nephi, UT – the sites of my first two soaring contests that I had registered for.

Then, as we all know too well, everything changed.  Much of the world went into lockdown.  The contests I had signed up for were cancelled.  And instead of soaring, I found myself drafting a Covid-19 policy for our club to help us get back in the air. After all, “social distancing” isn’t all that difficult in our sport.

Club operations resumed in early May.  And by the end of that month the OLC Speed League Season started with a five week delay.

Looking back at 2020, the soaring year turned out much better than expected. These were the goals that I had set for myself a year ago:

    1. Stay safe by always heeding my own advice.
    2. Move up to flapped gliders, fly with water ballast, and learn to responsibly use an engine.
    3. Have fun flying my first soaring contests (I’m signed up for the 2-seater Nationals in Montague, CA; and the Region 9 Sports Class in Nephi, UT). My goal is to complete all tasks provided that I can do so without taking any safety risks.
    4. Contribute to my club’s OLC Speed League results by scoring among the top three Boulder pilots on 10 or more Speed League weekends. My stretch goal for the OLC Speed League is to score among the top 5 Boulder pilots and among the top 50 US pilots overall.
    5. Complete a flight of more than 750km. My stretch goal is 1000km.

How did I do?

Despite the challenges we all faced, the soaring year 2020 turned out better than might have been expected.

My 2020 XC soaring flights from Boulder (KBDU). I significantly expanded my soaring range in 2020 – in part due to a better glider, and in part due to increased experience. The distance between the furthest points in the north-west (Crestone Junction, Wyoming) and south-east (Greenhorn Mountain) is more than 300 miles (just under 500 km).

Goal #1 – Stay safe.

This will always be my most important objective.  I’m glad to say I succeeded in staying safe.  However, I recall one situation where I pushed my luck further than I should have when I continued a particular flight under a rapidly over-developing sky.  This got me into a terrifying situation: I had to return across a line of thunderstorms with lightning flashing across my canopy.  While the outcome was benign, the experience was scary and not something I ever wish to repeat.  I have definitely been much more respectful of potential thunderstorms ever since. At some point I must find the courage to write about it in more detail so others can learn from it, too.

Lightning flashes across the sky ahead as I had back to Boulder from South Park, breaking off one of my 750 km attempts on July 31.

Goal #2 – Move up to flapped gliders, fly with water ballast, and learn to responsibly use an engine.

My new-to-me Ventus 2cxT allowed me to make good progress.  Most of my summer soaring flights were with different levels of water ballast. I am now quite comfortable flying with high(er) wing loadings.

Flying with flaps has been much less of a deal than I had imagined.  The flap controls in my Ventus are extraordinarily well designed.  The pilot’s hand can comfortably rest on the flap handle. Making adjustments is no effort at all. Working the flaps is as intuitive as working the elevator.

The integration of flaps and trim makes trim adjustments largely unnecessary.  Hard to beat that design!

I started the sustainer engine a few times for test purposes but I rarely ever used it to climb, and I never used it to self-retrieve, although once I came close.  You could say that’s a responsible use of the engine but I wish I had got to know it a bit better. There’s more opportunity for that next year.

My Ventus 2cxT during it’s Annual Inspection. The glider is in excellent shape.

Goal #3 – First Contests.

Almost all US contests were cancelled and moved to next year so this will remain one of my key objectives in 2021. To practice, I did manage to travel one week to Nephi to fly with Bruno Vassel and a number of other XC pilots.  The experience was invaluable as I was able to fly a number of good tasks and am now much more familiar with the terrain and the prevalent energy lines. This flight also provided a taste of what racing feels like.

The chart above shows the flights that I flew out of Nephi at the end of June / beginning of July.

Goal #4 – Contribute to my club’s OLC Speed League Results.

Boulder has had it’s best year ever competing in the speed league with a number 2 placement in the US Gold League and the World League.

My own contribution met my objective of placing among the top 3 Boulder pilots on more than half of the speed league weekends.  I learned a lot about flying faster and feel much better prepared for future XC flights.  I wrote more about my learnings from the Speed League in this article.

Among all Boulder pilots I over-achieved on what my stretch goal of scoring among the top 5 pilots overall by coming in 3rd place behind John Seaborn (a multiple national champion) and Bob Caldwell (one of Boulder’s most accomplished XC pilots). Among all US Speed League pilots I scored 25th, also well within my goal of landing among the top 50.

My fastest-ever glider flight was on a Speed League weekend in July – in classic Boulder convergence conditions. The average speed for the 2 1/2 hour speed league segment was 173 kph. The circling percentage was 6.5% with an effective glide ratio of 177:1.

Goal #5 – Complete a flight of more than 750km.

It took me eight attempts but on August 7 I ultimately achieved my objective of completing a pre-declared 750km flight.

My longest flight of the year (per OLC rules) was 916 km.  I’m now inspired to reach for 1000 km if the conditions permit.

14er Challenge.

In addition to these goals I also made good progress on the 14er Challenge: flying over the peaks of all mountains in Colorado that are at least 14,000 ft tall. At the beginning of the year my tally stood at 11 out of the 58 peaks.

In 2020 I succeeded in “bagging” another 28: the fifteen 14ers of the Sawatch Range, the seven 14ers of the Elk Range,  and five of the ten 14ers in the Sangre de Cristo Range.  I also flew over Mt. Bross, my last missing peak in the Mosquito Range.

My overall tally is now at 39 with another 19 peaks to go: the five southern-most peaks in the Sangre de Cristo Range, and all 14 peaks in the furthest-away San Juan Mountains.

Total XC Distance.

In 2020, I flew a distance of 19,728 km (based on OLC plus rules using a maximum of 6 legs per flight), almost half-way around the earth, at an average speed of 116 kph.

In my next post I will try to set new goals for 2021.

Do You Know Your Turf? – Off-Season Homework for Cross-Country Pilots

We all know pilots who fall into one of two buckets. Bucket 1 contains pilots who never leave glide range around their home airport. Bucket 2 contains pilots who don’t seem to hesitate at all before they venture out over completely unfamiliar terrain.

Bucket 1 pilots don’t know what they’re missing. Bucket 2 pilots don’t know what they are doing. The former will die of old age but with regrets in their hearts.  The latter might not get that far…

These two groups tend not to have too much in common except for one thing: they don’t know their turf. The first group because they don’t need to. The second group because they think they don’t need to.

And then there is a third bucket: it contains those who confidently leave glide range of their home airport, push their boundaries, and do so responsibly. These are pilots who want to live to old age and without regrets.

This article is for those who want to become a Bucket 3 pilot.  How can you join? Get to know your turf!

The place I fly from – Boulder, Colorado – is an extreme case in point. The terrain is unforgiving: there are mountains, canyons, woods, and rocks.  Boulder was given its name for a reason.  Except for airports that are often 40 or 50 miles apart there are few places to land.  And even some of the airports have runways too narrow to put a glider down.

When you’re flying a glider it is critical to know at all times where you can safely land no matter how promising the sky may be.  Even more so if the terrain ahead looks like this…

What about the prairie? Yes, we do have a flat prairie to the east of the mountains.  But it is rarely a good place to soar and the best lift is almost always over the mountains.

A basic rule of thumb for our area:  where you can land you can’t soar, and where you can soar you can’t land. (This is a bit exaggerated but you get the point.)

It is no wonder that our club has many Bucket 1 pilots who always stay within easy glide range of our airport.  Bucket 2 pilots are rare and a temporary exception: they tend to figure out quickly how get to Bucket 3 or they would not last very long. We also have many pilots who successfully graduated into Bucket 3.  It is these Bucket 3 pilots that make the Soaring Society of Boulder one of the most successful cross-country soaring clubs – not just in the US, but in the world.

If you have been a Bucket 1 pilot (wherever you fly) but want to join Bucket 3, what do you have to do and how long does it take?

Are You Ready to Become a “Bucket 3” Pilot?

Let’s acknowledge that you should have some basic competencies as a soaring pilot before you venture further afield.  E.g., you should be able to read the soaring weather forecast, tell the difference between a developing and a decaying cloud, center a thermal and don’t lose it. On a good soaring day you should have no difficulty staying aloft, and you should be able to confidently move from thermal to thermal.  Some pilots (usually younger ones) learn to get there within one or two seasons and about 50-100 hours of flying. Others may need a bit longer.

Three years ago, at the end of my first season flying from Boulder, I was one of those Bucket 1 pilots, eager and ready to figure out how to get to bucket 3.  My logbook at the time showed a total of 200 flights and 100 hours of soaring as pilot in command. 70 flights and 60 hours were in that one season; the rest dated back to my teenage years in the 1980s. All my flights up to that point had been local, i.e. within easy glide range of the takeoff airport.

What It Means To Know Your Turf

Cutting the cord to get back to your home airport is a huge milestone for any soaring pilot, second only to their first solo flight. It can also feel very intimidating. But you can remove a lot of the trepidations if you know what you are doing.

This means: be prepared before you venture off into the unknown!  You have to know the terrain that lies ahead and where you might find lift (or sink).  Most important of all: you must know exactly where you can land if the expected lift does not materialize.

Knowing where to land, how to ensure that you can always get there, and where you are most likely to find lift is at the very core of what it means to know your turf!

How To Learn Your Turf?

If you are new to cross-country soaring, chances are that you have some homework to do.  The same steps apply before you fly in an unfamiliar area.  As you gain experience you will become quite efficient in your learning process but that does not mean that should ever skip any of the following steps:

    1. Research viable landing sites
    2. Understand how high you need to be wherever you fly
    3. Familiarize yourself with typical energy lines (i.e. where to find lift)

Each of these three steps is discussed below.

My recommendation is that you select the most suitable soaring area beyond your home field’s glide range.  Let’s call it your Task Area.   Then you complete the three steps before pushing your boundaries further.  Keep your initial Task Area reasonably small – otherwise you might become overwhelmed and give up before you even make your first cross-country attempt.   Expand your turf one step at a time!

E.g., for pilots flying from Boulder, Colorado, it may be best to initially concentrate on the area east of the Front Range between I-70 and the Wyoming border.  This area is easily accessible, offers excellent soaring conditions, and provides access to several landable airports.  Only when you are completely familiar with this particular area, i.e., if you know your turf, does it make sense to research additional – and more demanding – areas to the south, west, and north, and north-east.

Suggested Initial Task Area for pilots flying from Boulder, Colorado. This area is about 90 miles from north to south. It offers great opportunities for a pilot’s first XC flights. Once you’re familiar with this area, expand your task area further.
This is a typical view above the northern foothills to the west of Fort Collins as I’m heading back towards Boulder. The terrain below is rolling and unlandable. I’m down to 11,300 ft and the Boulder airport (40 miles ahead) is no longer in glide range. Knowing the landing options is critical so I can concentrate on searching for lift.

If you don’t already know what the best area is for your first cross-country missions, I suggest you ask the more experienced pilots at your soaring site.  You want to select a task area that best meets the criteria just described.

1. Research Viable Landing Sites

Assuming you have prioritized and selected a task area for your first cross-country flights the first thing to do is to research where you can safely land.

a) Select suitable airports in your task area

Airports in your task area are easy to identify with the help of a sectional map (or an online version thereof – e.g.  Most will also be marked on the local waypoint database that you can find on the Global Turnpoint Exchange.

However, not every airport is suitable for landing a glider, or for your glider in particular.

Towered airports tend to have big and wide runways but they are not glider friendly.   I don’t like the stress of approaching a busy airport and explaining to a controller (who may know very little about gliders) why I am unable to stay in a holding pattern and need to land immediately.  I will use such an airport if I have to, but it’s not something I would recommend to anyone on their first cross-country flights.

Smaller public airports are usually the best choice but you have to know how wide the runways are and if the width will be sufficient for the wingspan of your ship.  A 60 foot-wide runway may or may not be sufficient for an 18 meter (59 ft span) glider: you also need to know if there are runway lights and whether they are immediately at the runway’s edge or located several feet to either side.   If you zoom into satellite images on Google Earth you can usually see the lights.  You can then use the online measuring tool to check the distance between them.

The screenshot shows the runway at Eerie, a typical public airport just east of Boulder. If you zoom into the satellite image the runway lights become easily visible and the measuring tool allows you to see that the distance between the lights is 80 ft. You should be fine landing there with an 18m glider (59ft span) but you will want to keep as close as possible to the centerline. With a 20m glider (e.g. our club’s DG505) you will want to be extra careful.

Private airports can also be acceptable choices but you need to be extra careful during your homework.  Often they are built and maintained for bush planes with high wings and narrow spans.  The terrain may be too uneven for the long and low-hanging wings of a glider, or the ground may be rising next to the edge of a narrow runway.

Online research is a good way to check them out but be very careful not to overlook anything! You can also never be certain that there aren’t any new obstacles when you turn up on final approach: e.g., there may be tall vegetation next to the runway that wasn’t there when the satellite image was taken.  A fence may have been erected.  Or a huge bison, a vehicle, playing children, or some other unexpected obstacle may appear in the middle of the runway when you arrive. If you land there, most private owners are likely to be welcoming but you may also find the owner absent and your retrieve crew stuck behind locked gates a long driveway away.

Under no circumstances should you trust that private airfields marked on the sectional map or on the waypoint file are suitable.  They might not even exist anymore and were just never removed from the map (or the waypoint file)!

Someone recently built this private runway at the north-west corner of South Park between Jefferson and Como, an area where a reliable place to land would be extremely welcome. The runway is 2000 feet long and 34 ft wide. But is it safe to land a glider? In my opinion, probably not. There is a fence post visible on the satellite image, which is 35 ft away from the centerline. Keeping my 59 ft glider at the center of the runway would probably let me avoid the post. But are there other posts that I may have missed? And what’s the obstacle shown a little lower in the picture directly at the runway’s edge? I don’t trust the place. If I have to land in that area I will look to one of the hay fields in the area as a better alternative.

Public airports are generally the best choice for landing out because they tend to present fewer surprises.  If the runway is long, smooth, and wide enough for an aero-tow take-off they may also offer the extra conveniences of an aero-retrieve.

b) Where to look for suitable land-out fields

In areas where suitable airports are far apart of poorly located relative to the best soaring conditions, land-out fields can offer a safe alternative.

In some soaring areas fields are large and plentiful.  E.g., driving through Texas I noticed that many fields are bigger than most airports and much of the area is as flat as a pancake.  At certain times of the year you can land practically anywhere.  Land-out Mecca!

However, if your soaring area looks more like Colorado than Texas, it pays to be strategic and ask: are there suitable landout fields where you might need them the most? Here are some prime examples:

Along your final glide path: a common scenario is that you return from a cross country flight at a time of day when the lift is dying.   If you are low and hit unexpected sink after you’ve passed the last airport on route, where would you land?  E.g., for those flying north from Boulder it is worth researching specific fields between Lyons and Boulder when Vance Brand airport is no longer an option.

The red arrow shows the typical final glide path for XC pilots returning to Boulder from the north. Marked in green to the left just south of the entrance to Left Hand Canyon is a cluster of three fields (hayfields and cattle pastures) that should offer a reasonable place to land if the pilot miscalculated the final glide. Another field is further south just to the west of Boulder Reservoir.

Along the base of the hills and in the valleys: soaring pilots normally fly over the hills and mountains because that’s where the lift tends to be best.  If our strategy is to always stay within glide range of a suitable airport, we may be forced to quit searching for lift over the hills and fly out into the plains to an airport while we are still quite high.  This means that having to land at that airport becomes very likely because it is usually much harder to find lift over the plains than over the hills.  However, if we positively know where we can safely land right at the base of the hills without necessarily having to reach an airport we can continue to search for lift over the hills, thereby greatly increasing the odds of avoiding a landout altogether.

This image shows the terrain west of the Northern Colorado Regional Airport (Ft. Collins/Loveland). This is a busy, towered, airport with a number of lakes in the vicinity. The odds of finding lift are much better above the hills and ridge-lines to the left of the image. If you quit your search over the hills with enough altitude to deal with the tower and the Fort Collins air traffic, you will most likely land at the busy airport. Knowing the location of suitable fields in the area (marked in yellow) gives you more time to continue your search for lift over the hills. (Do not rely on my assessment though – you must do your own research to verify whether a field is landable!).

Before major terrain obstacles:  if there are terrain obstacles along your flight path be prepared for the possibility of not being able to clear them.  A prime example for Boulder pilots is the northeast corner of South Park: Mount Evans is a big terrain obstacles for pilots returning from the southwest and if pilots fail to find lift to get over the mountains they must know the fields where they can safely land.

Not every terrain obstacle is as obvious as the peak of 14,264 ft Mount Evans, here viewed from South Park. This is the typical return route from the southwest to Boulder. If you cannot get past the mountains your only option is to land in one of the fields below. (You better know which ones are most likely to work.)

Across hostile terrain: glider pilots tend to fly along the same flight paths again and again because energy lines tend to set up in the same places (see chapter 4 below). If such flight paths include long stretches over largely unlandable terrain (e.g. undulating hills, big forested areas, etc) it can be vital to know the precise location of the few places where a somewhat safe landing may be possible.

E.g., for Boulder pilots flying towards Wyoming one such stretch is between Estes Park and the Laramie valley: 50+ miles of mountains, woods, rocks, and canyons with the nearest suitable airport often 30+ miles away. The only (private) airstrip at Crystal Lakes is too narrow for gliders but it is worth knowing the exact location of the only two meadows where an emergency landing might be possible.

Satellite view of “Crystal Lakes Airport”, the only marked (private) airfield in the northern foothills en route to Laramie. Would you land your glider here? I would rather not. It pays to know the location of the two meadows where it may be easier to accomplish a safe landing.

c) How to Research Specific Landout Fields

After deciding where to look for fields you need to do the work of identifying and verifying them.  If you are confident about a specific field in a strategic area you should load it into the waypoint database on your flight computer. This is the best way to quickly locate the field when you’re flying.

Starting Point: a good place to start is the Worldwide Turnpoint Exchange.  Locate the waypoint file for your area and view it with your flight planning software or in Google Earth.  Waypoint files are likely to include some landout fields. Just know that these were put together by volunteers, often many years ago, and you must never rely on them.  They are just a starting point for your own research!

Satellite Maps:  the next step in your research is to examine satellite imagery on Google Earth or Google Maps.  Familiarize yourself with the 3-D view and the use of the distance measuring tool.  If you locate a potential field in a strategic area, try to glean as much information as possible from the satellite image.

    • View the field from all sides in 3-D view to identify any slope. If a slope is visually noticeable the field will almost certainly be unusable.
    • Next, measure the length and the width of the field with the online measuring tool.  Then zoom in and carefully examine the surface: is it possible to tell what kind of field it is?
    • Can you spot farm animals?  Look for any visible rocks, buildings, ditches, irrigation equipment, or other ground obstacles.  Demarcation lines across the field (e.g. indicated by different shades of color) could suggest a fence which will not be visible from the satellite image.
    • Also check for power lines in the area (these may be impossible to detect but shadows sometimes give them away).  If there is a road next to the field, assume that a power line may run along the road.
    • If there are prevailing winds in the area consider what impact they are likely to have on the landing direction.
    • Imagine how you would fly an approach into the field to identify any terrain or approach obstacles.
    • Finally, examine the road access.  If a field looks good but seems inaccessible for a glider trailer it may just be of use in an emergency.

If you like a field and think it is worthy of further examination, try to do a preliminary evaluation and take notes of anything that may be of concern.  I note the GPS coordinates for each potentially viable field and make some initial evaluative guesstimates on a 5-point scale for each of the following characteristics: length, width, slope, surface, potential ground obstacles, approach obstacles, and road access.

I also note potential landing directions. If a field has some clear deficiency I may classify it as “emergency only”.  When I later visit a field on the ground I revise my initial evaluation – this process can be eye opening because the reality always looks different than the satellite image.

I use these criteria to evaluate the suitability of landout fields.

Examining the first few fields using this method will take a while but you’ll quickly get better at it. Note, however, that you can never positively identify a field as suitable just from an online review!

Visit and Verify: the only way to get reasonably confident about the suitability of a field is by visiting it.

There are two good ways to do so. The most thorough one is to visit the field on the ground.  Ideally you would want to walk around in the field but doing so may involve trespassing and attract unwanted attention.  But even just stopping next to the field and looking at it from the road will tell you a lot of things you might have missed.

Small to medium-sized rocks, uneven terrain, fences, ditches, or power lines are typical examples.  You might find out that the farmer is now growing tall crops in what previously looked like a hay field. You may find the field full of cattle. You may even find that there is no longer a field at all but a new housing development or a gravel pit..

Visiting fields makes you appreciate the static nature of a satellite image and is a powerful reminder for why you must not blindly trust your online research!

Photos taken during a ground visit to southern Wyoming. In rare situations even a road may serve as a safe landing site. This particular stretch of road met all my criteria. It was long and straight with very little traffic. Most importantly, there were no fences, poles, road signs, or other obstacles to either side and the road itself was slightly elevated relative to the adjacent fields which. (Often a road will be slightly lower than the ground next to it which could easily result in a violent ground loop.)

A good alternative (or complement) is to visit fields by air with a touring motor glider or a small power plane.  You might not be able to see everything as well as during a ground visit but you will gain another invaluable perspective: you can fly low approaches into the selected field with the engine idling and then go around.  It is easy to imagine what the approach would feel like in a glider.  Touring Motor Gliders are particularly well-suited for this endeavor.  Another advantage of this methodology is that you can see many fields within just one or two hours whereas a road trip to visit the same fields on the ground might take one or two entire days.

Can you not also examine fields from your regular glider the next time you fly over the same area? Well, you can identify where they are (and you should do that) but you will normally not be able to get close enough to learn much more than what you can learn from viewing satellite images. In Colorado, where we typically fly many thousand feet above the ground, almost every mountain meadow looks easily landable until you get low and close and it becomes obvious that you’d be lucky to survive if you had to put your glider in the middle of it.

Whether you do ground visits, air visits, or both, you should also familiarize yourself with the typical crops and their growing season in your area: what is being grown? how tall does it get? when is it harvested? is the ground soft or firm? In other words: which of the fields will be (most) suitable to land in at the time of your flight and how do you recognize suitable fields from the air? This is even more important if you do your ground visits in the off-season.  Fields look vastly different in winter than during the peak soaring season.  You should also research the types of irrigation systems being used (if any) and how you can avoid them.  Most irrigation systems will not stop when a glider shows up in the field and the machinery might just roll over it.

d) Practice With Condor

This isn’t a necessary step but it is super useful and fun.  If you have access to the Condor Soaring Simulator and there is a scenery for your soaring area, you can practice landing in your chosen fields.  This has multiple key benefits:

(1)  You become familiar with the visual view of the most hostile terrain from “down low” – a perspective that you hope to never see in real life.

(2) You experience what it would be like to land in the fields you have selected, and you test the approaches with different gliders and under different wind conditions.  If you ever have to use one of them, you’ll be better prepared and know what to do.

(3) You can repeat this exercise over and over again at no risk to you or your glider until you feel confident that you would not screw it up.

(4) You gain valuable practice for how to land in small fields – how to judge your altitude above ground, how to control your airspeed and glide path, how to clear obstacles, how to deal with cross winds and turbulence, and how to touch down with minimal energy.

These skills come in handy for all your future real-life landings and are invaluable if you have to put your glider into any small field.

A team of SSB pilots is practicing off-field landings in Condor at a private air strip northeast of Colorado Springs.

If you do practice with Condor, remember to never use it for the purpose of field selection!  Condor will allow you to land in lots of places that are not at all landable in real life!   You must select your fields in real life and use Condor only for landing practice!

Here is a video recording of a Condor flight to a number of emergency-only fields in the foothills of the Rocky Mountains. This shows you how to use this tool.  It is a lot of fun!

2. Understand How High You Need to be Wherever You Fly

One of the most fundamental safety rules in soaring is to always keep an airport or some other suitable landing site within safe glide distance.

However, applying this simple rule isn’t always easy.

a) Benefits and Challenges of Relying on Your Flight Computer

When you’re flying, the easiest method is to use the final glide calculator of your flight computer.

E.g., if set up to do so, my Oudie flight computer will display the expected arrival altitude above a specific airport or landout field if flying at the selected McCready setting (MC).

The screenshot shows the display of my Oudie IGC. You can easily see at a glance that Boulder and Lemons Field are within glide at an MC setting of 4.0 knots. I use a minimum arrival altitude of 1000 ft, which means that I can glide to Boulder and should arrive there at around 1640ft AGL provided that I fly at MC4 and there is no vertical air movement. If I glide to Daves Field, I would arrive 154ft below my safe pattern altitude, i.e. at around 846 ft AGL.

This works pretty well assuming that you selected the correct polar for your glider, that you accurately entered the weight of the pilot and water ballast, that you used reasonable bug settings, that you set an appropriate safe arrival altitude, and that you fly in accordance with MC.  It also assumes that there is no vertical air movement along your flight path, especially no unexpected and prolonged sink.

It took me about an entire soaring season to learn to trust my flight computer.  This has a lot to do with the fact that I did not trust myself to program it correctly.  Remember the standard rule for any analysis or machine output: if you put garbage in, garbage comes out!

I also learned to appreciate the impact of different MC settings (a higher setting gives you some extra safety margin because you can conserve energy by slowing down), and the significance of lift or sink along the way.  One of my more memorable learning experiences in this regard was on this long and somewhat exciting final glide.

Anyway, there are a lot of reasons for why I do not recommend that you simply trust the flight computer on your first cross-country flights!

b) Create Your Own Glide Map with Glide Rings

I recommend you use the off-season to study maps and determine for each part of your chosen task area how high you need to be to safely reach the next safe landing area.

How do you do that? You probably learned a simple and reliable method as part of your initial flight training: you take a map of your task area, mark the chosen airports and any personally verified landing fields, and then use a pair of compasses to draw concentric circles around each chosen landing site.  Each ring should indicate the minimum altitude that you need to be at in order to glide to the landing site and arrive there at a safe pattern altitude.

First, you pick a safe pattern altitude.  I recommend at least 1500 ft, especially for airports or fields where you have not landed recently.  For busy airports you may want to add some additional margin.

Then you pick a conservative glide ratio that is appropriate for “sinky” conditions.  Since you’re doing this exercise in the off season, you don’t know what the weather will be like on the day you’ll be flying, so err on the safe side.  I have encountered 10+kt sink for stretches of five miles or even more.  What’s conservative also depends on your soaring area.  This excellent booklet on mountain flying recommends to use half of your glider’s best glide ratio. In benign conditions this will feel overly conservative. In extreme conditions it may not be conservative enough! You may also want to discuss this with your flight instructor.

For Boulder I have created such a map with the help of Glideplan, a special piece of software that I bought for this purpose.  Note that this map is designed for high performance gliders and assumes a glide ratio of 1:27. It may thus not be as conservative as you want it to be!

Small excerpt of my Boulder Glide Plan Map. You’ll get the idea. Note that Glideplan does NOT account for terrain obstacles. See the next section below!

Glideplan is just a tool that facilitates the drawing of such circles on top of a current Sectional Chart but you can easily accomplish the same thing manually, using the process described above.  One advantage of doing this by hand is that you will better remember the information when you’re flying.  You can of course put a physical map with glide rings into your cockpit but I personally found it quite challenging to use during flight, especially when you are already relatively low and your workload is pretty high.

c) Account for Terrain Obstacles

Whether you create your glide map with glide rings, use a software to do so, or rely primarily on your glide computer: make sure you account for terrain obstacles that may lie between you and your nearest landing site(s).

Some glide computers such as the LX 9000, ClearNav, or even open source software such as TopHat and XC Soar will help you with this by displaying a “glide amoeba” on your screen.  This will show if your glide path is blocked by a mountain, hill, or ridge line.  Other computers such as the Oudie do not offer such a feature.

Whether you have such a computer or not, you should study the potential terrain obstacles that may exist in your task area and account for this by adjusting your personal glide map so that you positively know how high you need to be at any given point to clear any obstacles that may exist.  To do so, just use a safe minimum clearance altitude for your obstacles (e.g. 500-1000 ft) and then apply the same conservative glide ratio from there.

For pilots flying from Boulder, here is a brief list of some of the terrain obstacles nearby:

    • Flatirons – do not get low on the west side of the Flatirons.  Your only escape route may be through Eldorado Canyon and chances are that you will not make it back to Boulder.
    • Thorodin Mountain and Black Hawk – do not get trapped on the west side of Thorodin Mountain.  Your glide computer may show Boulder airport in glide but chances are that you’re not. There are no safe landing options in that area. You may not even be able to glide out to one of the (poor) fields near Golden.
    • High terrain east of Estes Park – if you get low in the Estes Valley, you will get trapped by the hills to the east. The landing options in Estes Park are marginal at best.  This flight got me to contemplate my options.
    • The Rampart Range.  This is a ridge line along the southern foothills roughly between Twin Ceders (south of Conifer) and Woodland Park (northwest of Colorado Springs).  Good lift can often be found along the convergence several miles west of the Rampart Range (e.g. near Cheesman Lake).  However, be careful not to get trapped over completely hostile terrain between the Rampart Range and the Terryall Mountains (the ridge line along the eastern edge of South Park) to the west. Your computer may show the private airfield of Perry Park in glide but there is no way to get there. Before you know it, ditching your glider in the lake could become the safest of all the unpleasant options.   On my first flight over Pikes Peak I dropped to 12,700 ft, uncomfortably low for in this area.

3. Familiarize Yourself With Typical Energy Lines

Following the advice in sections 1. and 2. above should help you stay safe during your first cross-country flights. This last section will help you find the most common lift lines within your task area.

It’s easy to see why that’s important: following lift lines makes it much easier to go places and you’re also more likely able to stay high and avoid having to put your land-out knowledge to an early test. After all, wouldn’t it be great if your first XC flights were successful and free of land-out-stress?

Most soaring areas have typical recurring weather patterns. For each weather situation, lift lines tend to set up in roughly the same places again and again.  This is especially true for mountain sites where ridge lift, convergence lift, and wave lift are a function of topography and wind. Many mountain sites also benefit from valley breeze, mainly a function of topography and sun angle. Thermals almost always set up first over the high ground where they are also stronger (albeit often narrower).


The most frequent energy line for Boulder pilots is the convergence that normally sets up east of the Rocky Mountains. In this image it is marked by low hanging “curtain clouds” to the right. The best lift is always just to the west of these curtain clouds. On some days you can fly straight along the convergence without having to stop and turn.

You will be able to obtain a wealth of information by talking to experienced cross country pilots at your site who are often eager to share their exploits.  Quiz them about what lines they fly most often in the most common weather and wind patterns, and what causes the more typical energy lines to set up.

Another way to find out is to download flight traces from flight sharing sites such as OLC (Online Contest).  Pick the better traces of pilots who are know to fly the longest and fastest tasks at your specific site.  Also, if competitions were held in your area, it is useful to download the flight traces from contest tasks.

Once you have found and downloaded such traces (20-50 traces is a good number to start), load them all into a flight analysis software such as SeeYou and overlay them on a single screen.   (OLC limits your download to 20 flights per day, so just stick with it over a number of days.) Chances are that the patterns will jump right out at you.

If you can see where pilots fly most frequently you still want to understand why they tend to find lift along the same lines.  The answers are likely very specific to your site and once again it is best to quiz these pilots directly.

In Boulder, by far the largest number of XC flights follows the convergence line that normally sets up over the foothills east of the Continental Divide and runs parallel to the mountains.  I have written multiple times about it.  Getting to the line is not always easy, but once you have learned to recognize and follow it, the rewards are amazing.  Understanding the convergence is really critical for local XC pilots. On strong convergence days it can be close to impossible to complete a successful XC flight if you’re to the east of the convergence.   It can be very frustrating for those who did not make it into the convergence to look at the amazing flights of those who did.  On the other hand, convergence days offer fantastic opportunities for badge flight such as my first diamond goal flight.

As an example of what you can learn from contest flights, take a look at this analysis that I completed in preparation for a contest in Montague, California.  The typical flight patterns are easy to see.  Conversations with pilots who previously competed there helped me understand the energy lines.

Bringing It All Together

“Bucket 3 pilots” don’t stay stuck in glide range around their home airport but neither do they head out blindly over unfamiliar and potentially hostile terrain.  Instead, they have done their homework.  They selected an appropriate task area. They know where they can land safely. For each part of their task area they understand how high they have to be to clear terrain obstacles and reach safe landing sites. They also understand the typical energy lines that tend to set up in their task area.  In other words: they know their turf.

By becoming a bucket 3 pilot you drastically increase your chances that your first cross-country flights will be successful, safe, and less stressful.

Boulder pilots can take a look at my personal Boulder Soaring Area Map where I have documented the results of my own research.  Instructions for interpreting and using this map can be found here. This is and will always remain a “work in progress”.  I have visited many fields on the ground, especially along the Front Range and across South Park.  An evaluation of fields along the Northern Front Range dating back to 2017 can be found here.

However, remember that such visits are just a snapshot in time based on what I could observe on the specific day of my visit. Our environment obviously continues to evolve.

Given the size of the covered task area, it would also be impractical to visit all the potential landing sites in person. If I am not certain about a field, I will only treat it as an “emergency site:” good enough to minimize physical harm to myself but not to my glider.  As a rule, I keep at least one good airport or a positively known landable site in glide at all times. I will only fly over “emergency-only terrain” when I am certain that I there is a line of good lift along the way.

If this seems like too much work remember to limit your initial task area!  Your first XC flights won’t lead you all across your state or even into neighboring states.  By selecting an appropriate and realistic task area for your first cross-country flights you can drastically reduce the scope of the required homework.  One or two weekends of online research, a few phone calls with experienced XC pilots at your soaring site, plus a day or two of visiting fields on the ground (or a flight in a touring motor glider) should give you plenty of information.

If that still feels like too much work there’s nothing wrong if you keep floating around your home airport!  After all, it’s your hobby and our choice what you make of it.  Just don’t succumb to the temptation of heading out into the hostile unknown!

However, if you have read all the way to the end, you must have what it takes to become a Bucket 3 pilot.  Have fun getting to know your turf!  I wish you great success on your upcoming cross-country missions.

Final Glide Ventus 2cxT vs JS3 – Is the JS3 Really Better?

Note: in the initial publication of this article I made a mistake when extracting data points from the JS3 polar curve.  Thanks to Matthew Scutter for pointing this out to me.  This error has been corrected below.

The published performance data from Jonkers Sailplanes and Schempp-Hirth, suggest a very significant performance advantages of the JS3 over the Ventus 2cxT.

The data suggest that a ballasted JS 3 flies 12% faster than a ballasted Ventus 2cT at a wing-loading of 51 kg/sqm.  Unballasted, the JS3 is shown to be 9-10% faster than an unballasted Ventus 2cxT.  (All data shown are for 18m configuration.)

However, one complication is that ballasted (or unballasted) the wing loading for the two gliders is different.

Let’s try to create a more “apples to apples” comparison by comparing the published performance figures at equal wing loading.  To do that we have to estimate the values for the JS3 at a wing loading of 51kg/sqm and that of the Ventus 2cxT at 40kg/sqm.  (To create the estimate I assumed that the attainable speed at a given sink rate for each of the gliders increases linearly with additional wing loading.  This methodology is probably not exactly accurate but any other plausible method would yield almost identical results.)

The table shows that even at equal wing loading the polar data still suggest a performance difference of 6-7% for the JS3.

[Side Note: per the manufacturer flight manual my Ventus 2cxT has a maximum all-up mass of 600kg (1323 lb) and is not limited to 565kg (1246 lb) as the polar curve suggests.  I.e., the maximum permissible wing loading is 54.4 kg/sqm and not just 51 kg/sqm. ]

Do those data points hold up in reality?

A little while ago I wrote about a Practice Race Day in Nephi on July 1.  One aspect that I did not give much attention was the difference in glider performance between John Seaborn’s JS3 and my Ventus 2cxT.  John and I flew the last 92.7 km (57.6 miles) within just three minutes of each other, which makes the results directly comparable.

I took a closer look at our flight traces to see how well my Ventus 2cxT held up against John’s JS3.  As a multiple National Champion John is unquestionably the better pilot, so we should expect John’s final glide to be at least 6-7% faster than mine if the published glider performance data are true AND if we flew with identical wing loading. (Both of us flew with 18 meter configurations.)

I was flying with approx. 80 liter of water ballast that day, which means my wing loading was right around 10 lbs/sqft (49 kg/sqm), very close to the 51 kg/sqm that Schempp-Hirth uses for their published polar curve.

I do not know how much ballast John had on board (although I do know that he flew with water that day) but I think it is likely that his JS3 was at or close to maximum gross weight, which would mean a wing loading of more than 12 lbs/sqft (close to 60 kg/sqm).  At full wingloading his JS3 should be about 12% faster than my Ventus. 

Is this true?  Let’s see!

This image shows our starting position with both gliders overlapping in the same position. We both have one turn-point to go to (the red circle at the top right of the image), and then race to Nephi (shown at the top left of the image). The distance from our current position to Nephi is 57.6 statute miles (or 92.7 kilometers).

My flight trace is shown in red, and John’s is shown in blue.  Note that at this “starting point” John was exactly 3:00 minutes behind me.  My red glider is shown at 16:11:41 local time.  John reached the same spot (the location of his blue glider) at 16:14:41 local time.

What makes this flight so comparable is that we reached this location not only within 3 minutes of one another but also almost exactly at the same altitude.  In fact, I was at 16,428 ft MSL and John was at 16,508 ft, i.e., only 82 feet higher.

Let’s take a look at our positions exactly 5 minutes later.  I.e., my location as shown is at 16:16:41, and John’s position is shown exactly three minutes later, at 16:19:41.

We’re still neck to neck although John took a slightly more easterly line.  John also flew a little faster than me during his cruise, thereby losing more altitude, and decided to make two extra circles in good lift (where he gained 700 feet of altitude).  At 16:19:41 he was 270 degrees into his first circle.  My altitude was 16,672 and John’s was 16,494.  I.e., I was now 178 ft higher than John.

Let’s wind the clock forward another five minutes, i.e. 10 minutes into the glide):

There is still hardly any visible difference in terms of our location.  Since the prior position I had taken one pointless turn which netted absolutely no change in altitude.  John’s 700 ft altitude gain in his two circles is now reflected in a positive altitude difference between our gliders of 675 ft: I am at 15,639 ft and John is at 16,314 ft.

Purists may say that the true final glide only starts here since neither of us stopped to climb from this position until the finish.

Let’s jump ahead another five minutes. We’re now 15 minutes into the glide:

John took advantage of his positive altitude difference and flew significantly faster than I did.  He is now almost exactly 2 miles (3.2 km) ahead of me and about to enter the final turn point.  At our flying speeds this means that John is now almost exactly one minute ahead.  However, John’s higher speed came at the price of 1000 ft of additional altitude lost over the past five minutes: while he was previously 675 higher, he is now 371 ft lower.  I’m now at 14,697 and John is at 14,326.

Once, again, let’s jump another five minutes ahead.  We’re now 20 minutes into the glide:


John is still approx. 2 miles ahead.  I have put the nose down with the finish in sight and am more rapidly losing altitude.  At such very high speeds there is a steep price to pay for flying with less than maximum wing loading.  I am now at 12,010 feet and John is now almost 300 feet higher at 12,308 ft.

There is still just over five minutes to go, so let’s jump to the last checkpoint before the finish.  We’re now 25 minutes into the glide:

John expanded his lead to 3 miles (5 km).  He’s been flying close to Vne and is now also dropping altitude more quickly.  John’s altitude is now 9,365 ft and I am now almost 1000 ft higher at 10,327 ft.

It’s now obvious that John is clearly ahead and I can’t do anything to catch up.  Let’s look at the finish line:

John is crossing the finish at 16:40:11 at an altitude of 9,221 ft. My position is shown at 16:37:11 (exactly 3 minutes earlier to maintain the same 3:00 minute difference that we have started out with).  I’m still exactly 3 miles (5 km) behind and at 9,983 ft.

I will cross the finish line at 16:38:30 at an altitude of 9,671 ft.

John’s 93km glide took him a total of 25 minutes and 30 seconds, and mine tool 26 minutes and 49 seconds.  In other words, the entire final glide took me 1 minute and 19 seconds longer than it took John.   The difference of 1 minute and 19 seconds is 5.1% (79 seconds / 1530 seconds).

5.1% is quite significant but it is clearly less than the published polar curves suggest, especially if John flew close to maximum wing loading.

In addition we can see that John also lost 532 ft more altitude than I did during the final glide (John lost 7287 ft whereas I lost 6755 ft).

It would be tempting to say that at John’s average climb rate of 490 fpm for the entire flight, it would have taken him 1 minute and 5 seconds to gain that 532 ft of altitude and the net advantage of his JS3 on final glide was therefore only 14 seconds (1:19 minus 1:05 minutes) – i.e. only 0.9% (14/1530 seconds).

However, such an argument – while mathematically correct – would miss the point that flying faster at a speed that would have resulted in an additional loss of 532 feet would not have allowed me to reduce my finishing time difference from 1:19 minutes to just 14 seconds.  The reason is that the speed polar drops off quite steeply at such high speeds.  A better way to save time would have been for me to just not do that one pointless exploratory turn.  This one turn cost me 50 seconds and netted no altitude gain at all.  Omitting this turn alone would have reduced my finishing gap from 1:19 to 29 seconds.

In summary I can say that my Ventus 2cxT held up quite well against John’s JS3.  In other words, it confirms that John’s superior performance over the entire flight has much more to do with pilot skill (e.g. during John’s only turn during the glide he gained 700 feet in 70 seconds compared to my 0 ft gain in 50 seconds) than with any performance advantage that his JS3 may have over my Ventus 2cxT.  This also is confirmed by my prior analysis of all other aspects of this flight.

Clearly, this analysis is just based on one flight and not under “laboratory” conditions.  It is not scientifically valid because not all variables were “held equal.” We did fly three minutes apart and it is possible (tough doubtful) that the conditions were more favorable three minutes earlier.  We also took a slightly different line above the Wasatch Plateau and I might have gotten lucky.  But I doubt it.  I’m fairly confident that the performance difference between the two gliders is exaggerated. If anyone wants to do the performance analysis for themselves, the flight traces can be found here:  John Seaborn’s trace and Clemens Ceipek’s trace.

Boulder Achieves Second Place in OLC World League – What Did I Learn?

On June 6 I published a “Beginner’s Guide to Scoring Well in the OLC Speed League“. This was – at least in part – written for myself as a guide for how to improve my own contribution.  Now that the Speed League is over it is a good time to take stock and ask “How Did I Do?” and “What Have I Learned?”

Boulder Achieved 2nd Place World-Wide, Out of 1029 Clubs

First of all, credit is due to my club, the Soaring Society of Boulder (SSB).  Out of 1029 participating soaring clubs competing in the World League, Boulder came in second place, beaten only by the outstanding team from the Minden Soaring Club.  Boulder has been doing well in the Speed League for many years but this is the best result for the Soaring Society of Boulder since OLC was created.

After a 9th place finish in Round 1, Boulder took the overall lead in Round 2 and then managed to hold on to first place until Round 9 when the soaring gods unfortunately had nothing but rain in store along the Colorado Front Range.  That gave Minden an opportunity to take the lead in Round 10, and Boulder was not able to catch back up.

The following table ranks the top 30 clubs in the 2020 World League.  The list includes 29 soaring clubs in Germany, seven in the western United States (Minden, Boulder, Tucson, Black Forest, Moriarty, Tehachapi, and Northern Utah), and one in Finland.

The full results can be found here.  Boulder came also second in the US Gold League, likewise only beaten by Minden.  The results are here.

How Did I Do?

One of my goals for the year was to make a significant contribution to SSB’s League Results.  I wanted to measure this specifically by scoring among the top three SSB pilots on 10 of the 19 planned Speed League Weekends in 2020. (The top scores of three different pilots affiliated with a specific club count for the club’s overall results – hence my objective to be among the three pilots whose results get counted.)

The Covid pandemic caused a six week delay in the start of the Speed League and the League was shortened from 19 weeks to only 13 weeks.  I therefore adjusted my goal accordingly to score among the top three Boulder pilots on seven of them.

I was able to fly on 10 of the 13 weekends.  And I did achieve my goal of seven scores among the top three participants:

I had two first place results (Round 3 and Round 7), four second place results (Rounds 1, 2, 6 and 8) and one third place result (Round 4).  In addition (not counted), I also came in second in the rained-out Round 9 when none of the Boulder pilots achieved a qualifying score (a minimum of 40 points).

Over the course of the season, 24 individual Boulder pilots contributed to SSB’s overall team score.  This is more than ever before and shows the breadth of SSB’s soaring talent.  The following table lists the top 10 contributors sorted by their “Contributing Points”, i.e. the cumulative number of OLC Speed Points for those rounds when the pilot’s score was among the top 3 SSB results.  By this metric, I was among the top three contributors of my club behind CX and BC.


    • “Rounds Flown” indicates the number of rounds that a particular pilot participated in and achieved a Speed League Score of at least 40 points.  Only flights on Saturdays and Sundays during the 13 week long Speed-League Season count.
    • “Rounds Among Top 3” indicates on how many weekends a pilot’s score was among the best three results; i.e. their score ultimately “counted” for SSB’s overall Speed League Score for that particular weekend.
    • “Total Points Earned” is the cumulative number of Speed League Points a particular pilot earned for all their flights during the entire Speed League Season (remember, only flights on Saturdays and Sundays count).
    • “Contributing Points (In Top 3)” is the cumulative number of Speed League Points of a particular pilot for those weekends when their flight was among the top 3 SSB results. Note: if a pilot would score among the top 3 pilots on every one of the weekend that they flew, their number of Contributing Points would be equal to their number of Points Earned.  The fact that only one pilot scored among the top 3 on every weekend they flew (XR) underscores the breadth of overall team member participation.
    • “Contribution Per Round Flown” simply divides the “Contributing Points” of a pilot by the total number of rounds that they participated in.
    • “Contribution Per Round (Top 3)” divides the “Contributing Points” by the number of rounds when they scored among the top 3 SSB pilots, i.e. the number of rounds when their results counted.

Given that this has only been my third cross-country season I am definitely happy with my result.  However, the point of this analysis is not to congratulate myself but to determine how I can improve going forward.

What Did I Learn?

I took a close look at eight speed league weekends when there were enough comparable flights to assess my performance against that of other pilots. Why only 8 instead of the 10 that I participated in?  I removed the Speed League weekend when I flew from Nephi because my flight would not be comparable to those flying from Boulder.  And I removed one weekend when I broke off my flight after 90 minutes due to thunderstorms.  (Speed League Scoring is based on the best 2 1/2 hours, and my 90 minute flight would not have been comparable.)

To ensure a good dataset, my analysis only includes flights flown from Boulder and only flights flown on the same days that I was flying.   My objective was to do an “apples to apples” analysis of specific flights, not a comprehensive analysis of all SSB Speed League Flights!  (E.g., None of John Seaborn’s winning speed league scores are included because they were not flown from Boulder. Also excluded are flights by any pilot on days that I did not fly at all. )

The following table shows a summary of key stats from the best 2 1/2 hour flight segments that are automatically selected by OLC.

Before we dive into the data, it is important to note that only the results of CX and BX are truly comparable to my own (V1) because only CX and BC flew on almost all of the days that I was flying.   (Y flew on 5 of the 8 days that I flew; AO, kW, and XR only flew on 2 of the 8 days that I flew.  It any of them wanted to draw conclusions about their relative performance it would be better to only look at flights on the days that they flew instead, and not at the aggregate results across rounds that they did not participate in.)

With that caveat out of the way, what do the data actually tell?

First, they show that I (V1) had the lowest circling percentage of any pilot at only 13% and the Highest Effective Glide Ratio of 172:1.  This is indicative of a certain flying style that prioritizes staying in rising air and – probably – flying relatively slowly, and possibly also accepting significant course deviations.

I already noticed the same tendency in my race analysis of the Nephi Practice Day on July 1.  There, too, did I have the lowest circling percentage and the highest effective glide ratio in cruise flight.

Unfortunately, as I pointed out in the aforementioned article, circling percentage and effective glide ratio are both composite metrics that are not only based on a pilot’s ability to follow energy lines, but are also a function of a pilot’s inter-thermal cruise speed. To truly understand a pilot’s ability to follow energy lines we must look at the average “netto” value while in cruise flight because this metric is independent of a pilot’s chosen flying speed.

Unfortunately, the OLC flight analysis does not provide the netto value.

Second, the table above shows that my 5.7 kt average climb rate in thermals was fairly competitive as well.  Only CX climbed a bit better at 5.9 kt average, and kW had an outstanding average climb rate on one of his two flights resulting in an average of 6.5 kt.

Based on the flight stats that OLC provides it is impossible to tell why my average League Points per flight trailed the performances of CX, kW, and XR.

Multiple possible reasons come to mind:

    • Sub-optimal cruise speed between thermals (possibly too slow)
    • More course deviations than other pilots
    • Too much time lost in thermal tries
    • Other factors

Unfortunately, OLC does not provide any data to gain insights into these potential factors.

In search for more answers, I turned to See You’s flight analysis software from Naviter.  However, See You cannot isolate the best 2 1/2 hour OLC Speed League Segment and so it is necessary to examine the entire flight instead.  This may not be too bad except that pilots tend to disregard competitive considerations once they have exhausted their 4 speed league segments.  E.g., in Boulder it is not uncommon for pilots to loose many thousands of feet of altitude at the end of their flight by deliberately following lines of sink instead of lines of lift.  Or they simply pull out the spoilers to lose excess altitude.  Needless to say, such actions distort any performance analysis.  In addition, Boulder is notorious for difficult climbs at the beginning of a flight until the pilot is “connected” with the upper level lift band. Pilots who get “stuck” early in their flight often spend an hour or more in weak lift trying to climb out while others take a higher tow and find good lift straight away.  These factors also distort the analysis.  It would therefore be much better to isolate the speed league segments only and be able to analyze the flying performance just for the part of the flight that actually “counts”.

So everything from here on must be viewed with these caveats in mind.

Circling Performance

As we’ve seen above, I only circled 13% of the time during the Speed League segments of my flight.  The relative impact of my circling performance is therefore lower than it would be if thermaling had accounted for a larger proportion of my flights.

The following table compares my circling performance to that of the other pilots flying on the same eight days.

Interestingly, my average circling percentage only goes up from 13% to 16% if I look at the entirety of my flights.  This is somewhat surprising because it includes the initial climb-out phase, and suggests that I was on average lucky to find good thermals soon after releasing from tow.

Most of the other metrics also show favorable results for V1.

    • My average climb rate is shown as being the highest of all pilots.  I do not put all too much stock in this metric though because this metric can be easily distorted by several factors.  I already mentioned the initial climb out when it is fairly common to spend 30-60 minutes or even more in very weak lift (1 kt or even less) before getting into “good air” on the west side of the Front Range convergence. Another potential distortion can occur when a pilot deliberately circles to lose altitude prior to landing.  See You will treat this just like thermaling and the result is that the data unfortunately becomes useless for comparison purposes.
    • I calculated the “Average Loss Ratio” in thermals as the ratio of altitude lost compared to altitude gained while thermaling.  I think of this as a metric of effective thermal centering:  the lower the loss ratio, the better the thermals are centered because the glider is in lift most of the time while circling.  The data shows that only CX had an equally low loss ratio in thermals.  (However, the caveats mentioned above apply here as well.)
    • “Average Tries” measures how much time during the flight gets wasted by trying out (and ultimately rejecting) thermals.  See You uses 45 seconds as the “cut off” time; i.e. if the pilot circles for less than 45 seconds before moving ahead on course this is deemed to be a “try”.    At 2.5% my “Average Tries” percentage might be a bit higher than I think it should be.  CX spent only half as much time trying out thermals.  However, I’m not sure what value is ideal.  At first glance it would seem that the lower the better, but a very low tries percentage could also suggest that a pilot is not rejecting enough weak thermals.  (This would show up as a low average climb rate, which is certainly not the case for CX.)
    • “Average Altitude Gained/Lost During Tries” subtracts altitude losses from altitude gains during tries and calculates an average value per flight. I was a little surprised to see that the value was overall positive for my tries which suggests that I rejected weak climbs but that I did not lose altitude during these tries in aggregate.  Most other pilots did lose more altitude than they gained during their tries.

Overall, I’m not sure that the Circling Performance Analysis provides strong indicators that would suggest specific improvement opportunities.  Cutting my “tries” percentage may help but only if it doesn’t lead me to reject really good thermals as well.

I believe there exist are other improvement opportunities for me but they are not specifically suggested by the data.  E.g., I believe I could achieve better climb rates by tightening my circles, and flying slower in thermals.  But to see this I would need to be able to compare my orbit times and ground speed in thermals to that of other pilots, especially in correlation to effective climb rates achieved.  I also believe that I can further improve my aileron/rudder coordination in thermaling flight.

Cruise Performance

If the thermaling analysis is somewhat inconclusive in terms of identifying improvement opportunities, maybe more can be gleaned from an analysis of the cruise flight segments.  Let’s look at the table below.

The first thing that jumped out to me is that my Average Effective Glide Ratio is still by far the best of any pilot (not surprising given that I also had the lowest circling percentage – which really is just the mirror image of this metric), but that my netto value is not as high as that of CX and XR.

As I mentioned before, netto is a much better metric to look at than effective glide ratio or thermaling percentage because it much better isolates a pilot’s ability to follow energy line.

A difference of 0.1 kt is certainly not a huge negative but it adds up, especially if one spends most of the time cruising!  Consider this: since my thermaling percentage is only 16%, I spend 84% of my flight time in cruise flight.  In other words: in aggregate, I cruise more than 5x longer than I circle (84/16=5.2).  So, when the cruise percentage is that high, over the duration of an entire flight a 0.1 kt vertical speed difference while cruising is approx. equivalent to a 0.5 kt vertical speed difference while climbing!  Looked at this way, it’s definitely not irrelevant.

On the other hand, the data set is not large enough to draw any conclusions.  Following energy lines is as much an art as it is a science and the location and strength of energy lines is so variable that an analysis of just eight OLC flights (where each pilot flies at different locations and at different times within a very wide area) is certainly limited with respect to assessing skills of improvement opportunities.

What we can say from the data, however, is that the effective glide ratio is likely very significantly impacted by the average cruise speed:  CX had the best netto value (1.6 vs 1.5 for V1) but his average effective glide ratio was significantly worse than mine (63 vs 107).  The main difference is most likely CX’s higher average cruise speed (83 kts vs 79 kts after adjusting for the glider’s index). The higher cruise speed resulted in a higher sink rate during cruise, therefore a lower effective glide ratio, and hence more time spent circling. Still, CX had the overall better performance so it is likely that his combination of flying speed and climb rate in thermals gave him an overall edge.

Another possible explanation for the difference in performance is the percentage of course deviations.  This seems such an obvious potential differentiator that one would think that the flight analysis software would provide this metric! Unfortunately this is not the case and there is no practical way to compare the extent of course deviations over eight flights manually.


Unfortunately, the insights gained from a detailed analysis of eight Speed League Flights are inconclusive with respect to truly understanding the performance differences and identifying specific areas for improvement.

The data suggest that my strengths include the ability to follow energy lines and centering thermals.  This is also consistent with my findings in Nephi. These are core skills that have a very significant impact on overall performance and are key pillars of my current performance.

In addition to further honing these strengths, I believe I can further improve in the following areas.  However, better flight analysis tools would be needed to confirm that these are more than “hunches”:


    • Better use of the full height band (increase in average climb height per thermal) / more selective in accepting thermals
    • Tighter circling (shorter orbit times – aim for around 25-27 seconds when ballasted, less without ballast.)
    • Slower orbiting speed (e.g. stall speed for the applicable bank angle and wing loading plus ~2 kts)
    • Further improvement in aileron/rudder coordination


    • Slightly reduce number of tries (but don’t aim for zero!)


    • Increased cruise speed, even when flying in lift along energy lines, with more aggressive pull ups in strong lift
    • Possibly reduce course deviations (need to be able to measure)


Opportunities for Providers of Flight Analysis Software – Especially for OLC!

To perform a more insightful analysis of OLC flights, a software would have to be able to isolate the portion of the flight that is scored by OLC.  I.e., for Speed League Scores it would be necessary to specifically analyze the performance during the 2 1/2 hour Speed League segment (maximum of four legs as defined by OLC rules).  For OLC plus flights, the relevant six legs would need to be isolated, again, based on the same rules that OLC applies.   Once that is accomplished, the software would have to be able to calculate the following key data points:


    • Average climb rate in thermals;  (ideally also the median climb rate)
    • Circling Percentage
    • % time spent in weak / medium / strong thermals (e.g. <2.5 kts; 2.5-5 kts; >5 kts). This is of interest because time spent in weak thermals is the #1 speed killer.
    • Average orbit time in thermals – a measure of how close one is able to fly to the core
    • Average speed while circling in thermals (air speed or ground speed) – in conjunction with orbit time another key metric to measure one’s ability to stay close to the core
    • Number of thermals
    • Average height gain per thermal – this is important to understand how much of the lift band one is able to exploit; greater height gain means fewer thermals, which fewer centering losses
    • Loss ratio (altitude lost / altitude gained while thermaling) – a measure for one’s ability to center thermals and keep them centered

Isolate Tries from Thermals and from Cruise:

    • % time in tries
    • Number of tries
    • Altitude gain – altitude loss in tries


    • % time in cruise flight
    • Netto during cruise flight only (excluding thermals and in thermal tries)
    • % course deviation (i.e. actual course track flown / scoring distance)
    • % time in netto rising air, and ideally also:
      • % time in weak / medium / strong lift (e.g. <2.5 kts; 2.5-5 kts; >5 kts)
      • % time in weak / medium / strong sink (e.g. <2.5 kts; 2.5-5 kts; >5 kts)
    • Average cruise distance between thermals (excluding tries)
    • Effective glide ratio (but this has mostly entertainment value)

OLC already has an enormous repository of flight data and would be in an excellent position to provide these analysis tools.  Introducing such tools as a subscription offering could also be a revenue opportunity for OLC.  Such a tool could allow pilots to benchmark their flights against those of others who flew in the same area on the same day.  I believe this would be a highly valuable add on and many pilots would be willing to pay extra for such insights.

Introducing such a tool could also pave the way for additional “big data” analyses of OLC flight traces.  The opportunities to provide deep insights are enormous. E.g., flight traces could be used to create “heat maps” of “house thermals” or other highly active thermal areas.  Frequently flown XC routes could be identified similar to how Strava shows routes that are frequented by runners or bicyclists.  Anyone who’s exploring a new area, taking a soaring vacation, or just simply planning cross country flights would find huge value in such tools.

It would be easy to anonymize the data that is being used for such analyses such that data privacy considerations can be addressed.

Unfortunately OLC is not (yet) taking advantage of its data repository. Worse, by limiting flight trace downloads to 20 per day it even prevents soaring pilots from exploiting this treasure trove of data on their own.  There’s a tremendous opportunity to create real value for the soaring community. I hope someone will!

Race Day 2020 – July 1 – Nephi

Covid destroyed my plans to fly my first two soaring contests in 2020 – the 20m-2-Seater-Nationals in Montague, CA as well as the Region 9 Sports Class Contest in Nephi, UT.  Both of these contests were postponed to 2021.

But there was one day in 2020 when I did fly in a friendly race: a bunch of pilots including myself made their way to Nephi for a practice week in preparation for next year’s contests.  And on July 1 the organizers declared a contest task fit for the 18 meter class.  It was the only day of the year where I flew exactly the same task as several other pilots.  One day isn’t much to go by, but I wouldn’t be me if I skipped the opportunity to analyze the results.  Especially since one of the pilots was John Seaborn, a multiple National Champion, and a fellow Boulder pilot. Don’t pass up an opportunity to learn!

The Task

The task was a Turn Area Task (TAT, aka AAT) with three assigned turn areas:

    • Start: 04 SE Start – radius 5 miles
    • TP1: 66 Nine Mile Ranch – radius 20 miles
    • TP2: 81 Table Mountain – radius 20 miles
    • TP3: 15 Browns Peak – radius 5 miles
    • Finish: 05 Finish (i.e. Nephi Airport) – radius 2 miles

Task Distance: from 275.2 miles minimum to 447 miles maximum (364.4 miles from the center of each turn area to the next)

Minimum Task Time: 3 hours (this seemed extremely short to me based on the task distance, so I basically decided to ignore it and just fly around the task as fast as possible). There was no declared maximum start altitude.

The Pilots

There were 18 pilots flying from Nephi that day.  However, flying the task was entirely voluntary and I don’t know how many attempted it.

At least six pilots uploaded flight tracks to OLC that show valid task declarations for this particular task in their flight recorders. Five of them finished the task.  I based my analysis on the five finishers because these flights are most directly comparable.

  • Pilot A, Hph 304 SJ 18 meter.  Current Pilot Ranking: 91. Holds FAI 1000km Diploma. Several top 5 finishes at Sports Class contests
  • Pilot B, LS3a 15 meter. No information found on the SSA website.
  • Pilot C, Ventus 2cxa FES 18 meter. Current Pilot Ranking: 73. Participated at several Regional Contests.
  • Pilot D, JS3 18 meter. Current Pilot Ranking: 100.  Multiple National Champion. World Championship Contender.
  • Pilot E, Ventus 2cxT 18 meter. No Pilot Ranking.

I am pilot E. 😉

Overall Results

I have attempted to score the flight according to SSA Sports Class rules and applied handicaps for the gliders (because one of them was an older 15m ship that clearly was not competitive with the 18 m gliders of the other 4 contenders.

This graph shows the task and the flight tracks of the 5 pilots who had valid flight declarations in their flight recorders and completed the assigned task.

These were the results (provided that I did the scoring correctly which is, frankly, insanely complicated):

  1. 1st Place: Pilot D.  1000 points (blue trace)
  2. 2nd Place: Pilot E. 823 points (purple trace)
  3. 3rd Place: Pilot A. 804 points (red trace)
  4. 4th Place: Pilot C. 783 points (green trace)
  5. 5th Place: Pilot B. 614 points (yellow trace)

The following table shows the raw speeds (before applying the handicap) and is easier to understand:

Avg. Speed (kts) 69.2 50.6 67.3 86.0 70.8

Not surprisingly, Pilot D – the multiple National Champion, let’s correctly identify him as John Seaborn :-), posted the fastest speed, and won by a wide margin.

Pilots A, C, and E were fairly close together (separated by 3.5 kts or 40 points), but far behind John. I was quite pleasantly surprised to find that I came in 2nd place, even though my performance was vastly inferior to John’s.

Pilot B was considerably behind everyone else.  However, his raw speed is not comparable because he flew an inferior glider (the 15m LS3a).


Just looking at raw speeds and point totals doesn’t really teach me anything except that I can’t compete with John Seaborn.  But that I already knew.

So let’s dig a layer deeper and look at some key stats to see some of the differences, in order to understand why John was able to score so much better than anyone else.

(1) Cruise Speeds

Given that John’s average speed of 86 kts was more than 15 kts faster than that of any other pilot it would seem likely that he flew much faster between thermals.

And in fact, John did indeed fly much faster than anyone else:

A B C D (John) E (myself)
Avg IAS during cruise flight 78 66 84 92 76

John’s average indicated air speed in cruise flight was 92 kts, 16 kts faster than mine.

John was also 15.2 kts faster overall on average so at first glance it would be tempting to attribute John’s superior overall performance primarily to his higher cruising speed.

But beware! This line of thinking would be a big mistake!

Let’s figure out how my overall average speed would have been affected if I had matched John’s speed and flown 16 kts faster during my cruise segments.  Had I flown at 92 knots instead of 76 knots, my sink rate would have been about 110 fpm greater than it actually was.  (Based on the wing loading of my Ventus 2xcT with partial water ballast my sink rate at 76 kts IAS was about 180 fpm; at 92 kts IAS (John’s cruise speed) it would have been ~290 fpm).

While flying faster would have meant that my cruise time would have shrunk by 17.4% from 196 minutes to 162 minutes (i.e, by 34 minutes), I would have lost an additional 11,700 feet of altitude (162 min x 290 fpm – 196 min x 180 fpm).  At my average climb rate of 4.2 kts (~420 fpm), it would have taken me 28 minutes to regain that altitude.

This means, my overall flight duration would have improved only by about 6 minutes, not by 34 minutes!  My average speed would have increased from 70.8 knots to 72.7 knots.  A little faster, yes, but still nowhere near John’s performance.  My point total would have increased from 823 to 845.

In other words, John’s higher average cruising speed explains about 1.9 kts of the 15.2 kts speed difference between his flight and mine.  That is 12.5% of the  total performance difference.

BTW – this improvement assumes that I would have been able to maintain the same 4.2 kt climb average and not been tempted (or forced) to take weaker climbs as a result of losing altitude faster.

Let’s also calculate what would have happened had I flown just 5 kts faster:  81 kts instead of 76 kts IAS.  My cruise flight duration would have been 186 minutes (10 minutes shorter) but my sink rate would have been approx. 25 fpm worse (based on my glider’s speed polar at my actual wing loading). In this case I would have lost an additional 2,850 ft over the course of the flight (196×180-186×205=2850), which would have taken me close to 7 minutes to regain while circling (2850/420=6.8). I.e., I would have saved a little over 3 minutes in total.

So, could or should I have flown faster.  Yes.  Would it have had a big impact? Probably not. Would it have made me as fast as John? Most definitely not!

The reality is that modest variations in average cruise speed by 5%, 10% or even 15% have only a fairly minor impact on the overall average performance because they are largely offset by the glider’s varying sink rates at different air speeds.  McCready’s speed to fly theory is of course accurate but its importance tends to be overrated. Especially because there is also a strategic price to pay for faster cruise speeds:  because the glider sinks faster to the ground the pilot has fewer options to select suitable thermals. This means that the faster flying pilot may find high average climb rates more difficult to attain. He or she also faces a higher land-out risk.

So, if John’s higher cruise speed wasn’t the main reason for his superior performance (it wasn’t), then what was?  Let’s look at other potential reasons below.

(2) Flight Duration

A B C D (John) E (myself)
Distance (miles) 291.9 285.7 326.4 297.1 313.2
Duration 3:39:57 4:54:01 4:12:42 2:58:50 3:50:36

In a Turn Area Task with a minimum task time, flight duration is a relevant factor.  The minimum task duration was 3 hours, and John optimized his time quite well – although he would have scored even higher had he flown the full 3 hours and not finished 1 minute and 10 seconds too early.  In fact, had he flown exactly three hours his average speed would have been 86.6 kts instead of 86.0 kts (assuming that he had enough altitude to extend his flight just a little at the last turn point – as in fact, he did).  0.6 kts may not sound much but it could make a crucial difference if the results are very close. (Per my calculations, the point difference between John and the other pilots would have been 6 points greater had he finished at an average speed of 86.6 kts instead of 86.0 kts).

Coming in “right on time” (or slightly above) is usually an advantage because the start altitude is considerably higher than the finish altitude and a pilot who flies just the minimum time (and no longer) is best able to convert that altitude difference into a higher average speed.

How big is this effect on a 3 hour task?  Not insignificant.  Math guru John Cochrane has done the work and given us some formulas to estimate the effect.  On a three hour task in western conditions, the cost tends to be about 0.5 score points per minute of overtime.  I.e. my 50 minutes of overtime might have cost me about 25 points.  I.e., instead of being 177 points behind John, I might have only been 152 points behind, had I been able to finish the task in 3 hours instead of taking 3 hours and 50 minutes.

In other words: my 50 minutes of overtime explains about 14% of the overall performance difference between myself and John.

(2) Circling Percentage

A B C D (John) E (myself)
Circling %age 23% 30% 23% 20% 15%

A popular metric to compare flights of different gliders is to look at the amount of time pilots spend circling versus cruising.  Since you’re not moving forward while you go around in circles, a high circling percentage tends to be a disadvantage.

John’s circling percentage was indeed quite low: 20%. However, it was not the lowest. In fact, I spent even less relative time circling than John did: only 15%!

But did this lower circling percentage give me a demonstrable advantage?  Unfortunately that is impossible to say!  The problem with the metric “circling percentage” is that it is a complex data point – a composite of several factors that include not only route selection (e.g. flying through lift vs sink), but also flying speed (if you fly slower your sink rate is lower, i.e., you arrive at the next thermal higher, and you need to circle less.)

Because of its composite nature it is impossible to say that the pilot with the lower circling percentage necessarily gains an overall advantage.

(3) Effective Glide Ratio

Highly related to the circling percentage is the effective glide ratio achieved in cruising flight.  This is in part a measure of how effectively a pilot is able to follow energy lines, but, just like the circling percentage, it is also a composite metric driven in part by the inter-thermal cruise speed.

The more effective one is at following energy lines, but also, the slower one flies, the less one needs to circle and the higher the effective glide ratio.  And indeed, the results show a mirror image of the circling percentage:

A B C D (John) E (myself)
Glide Ratio 73 40 66 79 93

My effective glide ratio of 93:1 was better than anyone else’s.  John’s 79:1 came second.  However, just like the circling percentage, this metric ultimately doesn’t mean very much.

(Note: a reader might wonder how it is possible to achieve such high effective glide ratios with gliders that have a “best” glide ratio of around 50:1 when flown at best L/D speed (i.e. much slower than we were flying). The answer, of course, has to do with the pilot’s ability to follow energy lines – areas where the air is on average rising instead of sinking or just standing still.  More about that right below.)

(4) Following Energy Lines

The circling percentage and the effective glide ratio might be taken to mean that I did better than anyone else in terms of following the best energy lines.  However, as I mentioned, both metrics combine the effects of following energy lines and the actual inter-thermal cruise speed.

A much purer measure for the ability to follow energy lines is the netto value during the straight flight segments.  Netto measures the actual vertical movement of the air that the glider flies through and is not impacted by the glider’s sink rate.  Hence, it just measures the effectiveness of the choice of route and is thus a much better metric to use.

A B C D (John) E (myself)
Netto in straight flight (kts) 1.8 0.5 1.6 2.1 1.6

This table shows that it was John who did the best job with respect to following energy lines.  During all of John’s straight flying segments the air rose at an average rate of 2.1 kts.  On this measure Pilot A ranked second with an average netto value of 1.8.  Pilots C and E (myself) were tied in third place with a netto value of 1.6 kts.

How much difference did this make?  John spent 2 hours and 22 minutes in straight flight.  During that time the airmass he flew through went up by an average value of 2.1 kts, approx. 210 fpm.  That is 50 fpm more than during my flight where it went up on average by 160 fpm.  Over John’s entire task this difference amounts to 7,100 feet (50 fpm x 142 minutes).  At my average climb rate of 4.2 kts (~420 fpm)  – see below – I needed 17 minutes to climb 7,100 feet.  On a 3 hour task, 17 minutes equals 9.4% (17/180).   And 9.4% is the difference between John’s winning speed of 86 kts and a speed of 78 kts.

In other words, John’s superior performance with respect to following energy lines explains 8 kts (more than 50%) of the 15.2 kts speed difference between our two flights.  It is thus the single most significant factor of John’s overall superior performance!

Since this is such a hugely important factor I also tried to understand specifically what John did better in terms of following energy lines.  This is very difficult to glean from the data alone but I was able to combine evidence from the flight trace and an analysis of my inflight video recording. Let’s take a closer look.

The following graph overlays the flight traces of John and I.  John’s trace is shown in red and my trace is shown in blue.

John’s flight trace is in red. My flight trace is in blue. Note the different choices with respect to approaching TP1 (the red circle on the top right) and TP2 (the red circle at the bottom left).

The graph above indicates where John and I made different route choices, especially with respect to approaching the first turn area (top right) and the second turn area (bottom left).  But it tells us nothing as to which of the two traces followed better energy lines.

Fortunately, SeeYou (the flight analysis software from Naviter) allows us to display the traces based on their netto values as well.  This is shown in the graph below.

Blue values show sections where each glider flew through sink – the darker the blue, the stronger the sink. Yellow, orange, and red sections show the glider flying through rising air. Yellow is light lift (0-3 kts), orange is medium lift (4-10 kts), and red is strong lift (more than 10 knots).

You have to be careful to remember which trace belongs to which pilot. That’s why I included the graph earlier that clearly shows which of the two traces belongs to John and which one belongs to myself.

At first glance there doesn’t appear to be too much difference.  But if we take a closer look at the approaches to TP1 and TP2, we can see some subtle differences in the color gradient.

Let’s look at the approach to TP1 first:

The differences are subtle but it you look carefully, you can see that my trace (the one further north) towards and away from TP 1 contains somewhat more blue segments than John’s (the one further south).

(Note: you can also see that I wasted quite a bit of time after turning TP1 trying to climb.  I was uncomfortable with my altitude and made a number of unsuccessful exploratory turns.  This was another contributing factor to my overall performance; it is discussed below under point (5) Climbing).

One might wonder: why did I fly such a northerly line to TP1, just barely nicking it and then heading back west?  The answer is in the following image, taken a few minutes before I turned right to nick the the turn area:

To get to TP1 I followed a cloud street to the northeast, which ran past the turn area to its north.  The turn area itself was in the blue to the right in the picture above.

Why did John decide not to follow the same line?  I don’t know for sure but I can speculate.  Let’s come back to this below after discussing TP2.

Here’s our different approaches to TP2.  Let’s look at the graph:

John’s trace is the one further east (right), and mine is the one further west (left). Once again you can see that there seems to be a bit more blue in my trace than in John’s trace.

Why did John take the easterly route while I took a more westerly line? Here’s what the sky ahead looked like as I was heading towards TP2:

In the picture above I am about 25 miles north of TP2.  I dare say there wasn’t much to go by to determine what route to take.  The sky was entirely blue.  I simply stayed above the high ground of the Wasatch Plateau and took pretty much every lift I could find to stay high.

As you can see from the trace, John flew a more easterly line.  Did he know something that I didn’t?

Here is the answer: John had started the task much later than I did and came to the same area about 20 minutes after I did.  Here is what the sky looked like by the time John was still about 25 miles further north:

A nice line of clouds developed further east that had not existed earlier.  John could see the clouds ahead and was able to follow them while I was already too close to the turn area by the time the clouds appeared.

This means that a key reason why John was able to find a better line to and from TP 2 was that he timed the start of his task better:  while I made the rookie mistake of starting as soon as I was up and seeing a path to get to TP1, John decided to wait for the day to develop further.  As it turned out, these 20 minutes played a big role!

Let’s revisit the approach to TP1 as well: I believe, John’s later start also allowed him to fly a more direct route into the first turn area.

The above image shows John’s trace.  Note the 90 degree kink in the line near Brown’s Peak on the left.  This is just speculation but I think that John may have changed his course because he could see the first cloud appear in the turn area, which had been completely blue when I approached it earlier.  You can see that John also didn’t just “nick” the turn area but continued into it for a few miles where he climbed in good lift.  I have to believe that a cumulus had formed by the time he entered the turn area (almost one hour later in the day than I did).  This would underscore the advantage one can gain by starting later and letting the day develop before going on task.  (Obviously this makes only sense when the better part of the day is ahead and there is no risk of being unable to finish.)

Note that by flying a direct line to TP1, John was also able to reduce the total task distance and finish much closer to the minimum finishing time.  Had he continued to the northern edge of the turn area (as I did), John would also have finished with overtime.  I discussed the advantage of finishing on time in Section (2) above.

In summary I conclude that John’s decision to start the task later was a key factor helping him follow better energy lines, because he was able to follow cloud lines that had not existed earlier and thereby increase the ratio of flying in lift vs. in sink.

(5) Climbing

Pilots who are able to thermal better than their competitors can also gain a major advantage.  And indeed, John’s average climb rate of 4.9 was clearly better than anyone else’s:

A B C D (John) E (myself)
Avg climb rate kts 3.7 3.9 3.8 4.9 4.2

The delta between John’s climb rate and mine is 0.7 kts or 70 ft per minute, just over 1 ft per second.  This may not sound like much but it adds up.  John spent 36.6 minutes circling.  In that time he gained about 2,500 ft more than I did (36.6×70=2562).  Which means: I would have needed six minutes longer to achieve the same gain of height (2562/420=6.1).   On a 3 hour task, six minutes are 3.3% or the difference between 86 kts (John’s winning speed) and 83.2 kts.

In other words, John’s superior climb performance explains 2.8 kts (almost 20%) of the 15.2 kts speed difference between our two flights.

Once again, I tried to dig a little deeper.  Did John actually center the thermals better or did he just do a better job at thermal selection?

The data point to both being factors:  John spent most of his circling time in 5, 6, and 7 kt thermals; whereas I spent most circling time in 4, 5, and 6 kt thermals.  I also wasted about 10 minutes trying to climb in sinking air and lost a total of 1500 ft whereas John wasted only 5 minutes this way and only lost 200 feet.

I lost this wasted time in two places: (1) when I got lower than I liked coming out of TP1 with still some blue sky to cross ahead, and (2) when I tried to stay high prior to TP 2 with only blue sky ahead.  (A later start may have helped reduce some of the wasted time because clearly marked thermals ahead would have given me more confidence and lessened the impetus to try every lift that I encountered in the blue.)

This difference of 1300 feet extra wasted explains approx. another 10% (or 1.5 kts) of the delta between John’s performance and mine.  The additional 5 minutes wasted account for another 3% (or 0.4 knots).

A B C D (John) E (myself)
# of Thermals 21 37 18 14 19
Avg Glide Distance (miles) 15.3 8.5 20.1 23 18
Avg Altitude Gain per Thermal (ft) 914 948 1270 1291 766

John also took only 14 thermals with an average altitude gain of 1300 feet per thermal and flew on average 23 miles between thermals whereas I took 19 thermals with an average altitude gain of less than 800 feet per thermal and only flew 18 miles between thermals.  This is illustrative of my overly conservative flying style.  (Another indicator is that my thermal entry altitude was consistently about 1000 feet higher than John’s.)

The number of thermals chosen and the average altitude gained per thermal do not impact the overall performance “per se”.  But they are an important reason as to why my average climb rate was lower than John’s:  each time you stop to thermal you have to first center the thermal before you can get the most out of it.  John did this 14 times and I did it 19 times.  It goes to reason that centering more thermals made my climbs less efficient and is a significant contributor to John’s superior climb rate.

(6) Other Potential Factors

(a) Speed Variations in Cruise Flight

One might think that pilots could gain a significant advantage by really slowing down in rising air and speeding up in sinking air.  However, the following chart shows that none of the five pilots varied the speed significantly from their average cruise speeds while flying through rising and sinking air.  The data are in kts IAS relative to the average IAS flown by each pilot.

A B C D (John) E (myself)
Slow down in rising air (relative to avg) -4 -5 -6 -5 -4
Speed up in sinking air (relative to avg) 2 1 2 2 2

I was especially surprised to see that none of the pilots sped up much while flying through sink.

I think the problem is that varying the cruise speed between lift and sink works great in theory but  is very difficult to do in practice.  If you find yourself in sink and speed up, chances are that you fly too fast through the next patch of rising air. Conversely, if you’re flying in lift and slow down, it’s quite possible that the lift will have ended by the time your speed has come down and now you’re going too slow in sink.  In the soaring literature this is often referred to as “chasing MC speed” and I am not the first one to observe that it doesn’t really work in real life.  In addition to always lagging behind in your reaction it is also inefficient to constantly vary your speed by pushing and pulling.  Obviously, it does make sense to vary your speed if you positively know what’s just ahead (e.g. if you’re closely following another glider and can observe it rising or falling). But in the absence of compelling clues it is often better to just maintain your speed during cruise.

(b) Tactical Turn Point Height

Turn Point 2 was located directly into a 13-16 kt headwind from SSW and provided an opportunity to gain an advantage by rounding the turn point low and then using the tailwind to gain altitude while moving on towards Turn Point 3.

A B C D (John) E (myself)
Altitude when rounding TP2 15,343 15,500 16,946 15,441 15,035

The table above shows relatively small altitude differences among the various pilots when rounding TP2 and suggests that none of the pilots gained a tactical advantage.   Turn Points 1 and 3 offered much less opportunity to gain an advantage.

(c) Start Timing

John Seaborn was the only one of the five pilots who seemed to deliberately time the start based on improving soaring conditions.  Everyone else started right after gaining sufficient altitude to get going.

A B C D (John) E (myself)
Start Time 13:07 12:49 12:12 13:41 12:48

It is impossible to directly measure the impact of the different start times.  However, as we have seen, waiting to start late was likely a key underlying contributor to John’s superior performance as it helped him follow appropriate energy lines and improve his climb performance.

(d) Start and Finish Altitude

Since this was just a practice task, there was not a declared maximum start altitude although I suspect John deliberately started lower for practice reasons. A higher start altitude would have provided an advantage.

A B C D (John) E (myself)
Start Altitude 13265 15637 15148 12558 15458
Finish Altitude 9410 8081 7582 9221 9645

Minimum Finish Altitude was 7000 ft and most everyone returned significantly higher than that.  I remember there being a lot of lift on the final leg and I flew close to Vne or the altitude and I still came in more than 2,500 ft too high.  John was just a few miles behind me and flew through the same air, also finishing high.

By starting ~3000 ft higher than John and finishing ~500 ft higher I gained a net advantage of 2500 ft, which translates to a six minute time advantage in my favor (2500/420=5.9) and can alternatively also be expressed as a speed advantage of 2.8 kts in my favor.


George Moffat explained in his classic book “Winning II” (p. 42-50) that winning can be viewed as the result of not losing.  He illustrates that the winner of any particular flight usually did several or many things (big and small) a little better than his or her competitors, and that the win can therefore be explained as a sum of all these things.

If I contrast John’s flight with mine, here is a summary of the things that John did better than I, and how much each factor contributed to the overall results:

    • Following energy lines (measured by netto in cruise flight) … 8 kts
    • John climbed better (measured by average climb rate) … 2.8 kts
    • Time and altitude wasted in “trying out thermals” … 1.9 kts
    • Finishing on time vs. finishing with 50 min overtime … 1.7 kts
    • More optimal cruise speed … 1.9 kts

Total difference: 16.3 kts

As discussed I believe that John’s decision to delay the start of his task until 13:41 (53 minutes later than my start) contributed to his ability to follow better energy lines, finish closer to minimum time, reduce time wasted in exploring thermals in the blue, and possibly even achieve a higher average climb rate.

From the 16.3 kts we have to subtract factors where John put himself at a disadvantage:

    • Net difference in start/finish altitude … 2.8 kts
    • John finished 1 min 20 seconds under minimum time … 0.6 kts

In sum, the analysis explains 12.9 kts (16.3 – (2.8+0.6)) of the overall speed difference between our two flights while the actual speed difference was 15.2 kts.  This leaves just 2.3 kts of speed differential unexplained.

I believe that some of the unexplained 2.3 kts may be attributable to John’s slightly superior glider (a new JS3 vs compared to my 17-year old Ventus 2cxT) and potential differences in wing loading (I flew with 2/3 water ballast; I don’t know John’s wing loading but it may have been higher than mine).

Key Lessons

(1) Focus Most on What Matters Most: Energy Lines and Climb Rates!

This deep-dive analysis of one single flight suggests that the following two  factors have the biggest impact on overall performance:

    • The ability to follow energy lines (as measured by “netto” in cruise flight)
    • The ability to avoid weak climbs, minimize tries in sink, and achieve a high average climb rate (selecting the most appropriate start time can play a major contributing role)

These two things not only have the biggest impact, they are also skills that one must develop and hone over time. And they are relevant on every single flight.

Over the past two seasons I have significantly improved my ability to follow energy lines but I still have a ways to go as this one flight clearly shows.  Starting a task later in the day can make energy lines more visible.

I have also been working on improving my climb rate in thermals and there are still some low hanging fruit such as thermaling slower and tighter.  The data suggest that I also have an opportunity to become more selective: I should skip more of the weaker thermals and use more of the available altitude band.  It is best to only take thermals that offer an average or better climb rate.  And it is critical to minimize the time it takes to center them.  That’s why it is generally better to take fewer thermals. In contests it is often best to take thermals marked by other gliders, precisely because others have already done the centering work for you (obviously assuming that they did it right.)  I was actually encouraged to see that my avg climb rate was “only” 15% lower than John’s.

(2) Picking the “Right” Start Time

It seems that picking the right start time was a key underlying contributor that may have helped John achieve a superior performance – especially with respect to following energy lines and achieving a superior average climb performance.

(3) Other Tactical Improvement Opportunities

Compared to the overarching factors above, everything else is secondary (although, of course, it also adds up).  Interestingly, most of the other contributing factors are more tactical in nature and can be more readily improved by an average pilot, including:

    • Not leaving potential energy on the table by departing too low or finishing too high.  The departure altitude is relatively straightforward as in contests it tends to be a given. The finish is trickier and my conservative approach means that I am likely to come in too high.  I will need to practice more final glides to gain the confidence to finish close to the minimum finish altitude.
    • Optimizing the finish time (avoid under time; minimize over time).  I have been practicing a few TATs and they are more fun than I initially thought. On this particular flight I believe that a later start time might have helped me pick a shorter flight path and finish closer to minimum time.
    • Flying closer to MC speed.  The stats on this flight showed – once again – that I am among the more conservative XC pilots. There’s definitely some room for me to fly faster and take higher sporting risks.  However, the rewards of flying faster are not huge and I will always have to balance this against the added land-out risk and the risk of having to take weak climbs that could destroy my overall result.
    • Turning upwind turn points low and downwind turn points high. This did not play a big factor on this particular task, likely because TP2 (where it would have helped) was in the blue and I therefore tried to stay high.  However, from my experience with Condor I know that this tactic can have a significant impact on the overall result.
    • Speeding up in sink and slowing down in lift.  This is great in theory but the data suggest that it may be impractical to do this efficiently in reality, especially with a ballasted high performance glider. Lift and sink tend to alternate so quickly that it is often impossible to vary the airspeed in a timely manner.  There is nothing worse than pulling up in lift only to find oneself in sink again right when the glider has slowed down; or conversely, to push down in sink only to find oneself shooting through the next patch of lift at high speed.

(4) Don’t Look Too Much At Composite Metrics such as Glide Ratio and Circling Percentage

Composite metrics that I have liked to look at in the past such as circling percentage and effective glide ratio achieved, have more entertainment value than analytical value.  You won’t win a race because you have achieved the lowest circling percentage or the highest effective glide ratio.  You primarily win the race because you consistently flew through better air than your competitors (as measured by netto), and because you achieved a high average climb rate, especially by picking  a limited number of good thermals and successfully avoiding weak climbs.

Seven Failed 750 km Attempts – What Did I Learn?

On August 7, I successfully earned my 750k Diplome by completing a pre-declared 757 km task with three turn-points.  It was my eight attempt at such a task. Here is the flight track. I’ve documented the flight in detail in the following video.


In this article I will NOT focus on the successful flight but instead on the seven failed attempts that preceded it.  I want to examine exactly what went wrong, when, and why. And most importantly: what did I learn from these failed attempts?

Attempt #1 – You’ve Got to Take This More Seriously!

On May 5, 2020 I declared the following task:

  • Start/Finish: Gross Reservoir Dam
  • TP1: Morton Pass, Wyoming (42 km north of Laramie) – 189 km
  • TP2: Lake George (30km northwest of Pikes Peak) – 296 km
  • TP3: Rustic (35 km north of Estes Park) – 191 km
  • Finish: Gross Reservoir Dam – 85 km

Task Distance: 762 km

I launched at 12:39 pm, released in the pattern, and spent about 45 minutes getting connected. The launch itself had probably been too late already and when I finally was ready to get on task it was clearly too late for such an endeavor.  I realized this at the time and didn’t even bother to head south to cross my start line at Gross Reservoir.

In retrospect, I am not sure I should even call this an “attempt” since I did not even get a valid start.  I went on to have a nice flight: 561 km at an average speed of 120 kph based on OLC plus rules was fun but a serious effort to achieve a declared 750 km task it was clearly not.

Another question is: could it have worked had I started earlier?  The honest answer is, “I don’t know”.  The day was fairly strong with a well-working convergence line.  I can’t be certain that the convergence would have worked all the way to my first turn point because I only flew north until Crystal Lakes and did not try to get further north from there.  However, a line of clouds indicated the location of the convergence and it seemed to be in the right direction albeit with a lower cloud base.

The following picture shows my location over Crystal Lakes looking north towards Laramie just before turning back south.

The clouds on the right mark the convergence line in the direction towards my first – and most difficult – turn point, which – at this point – is about 100km away.

The image suggests that it probably would have been possible to follow the convergence to the north – although maybe not at the same speed as the rest of my flight.  But by the time I got there it was already too late in the day.  What would the same location looked like two hours earlier?  Did the convergence exist at that time? Was it marked?  These questions are of course impossible to answer in retrospect.

Bob Faris and John Seaborn had the longest flights from Boulder that day with just under 600 km and no-one flew faster than my 120 kph average.  These stats suggest that the day may not have been strong enough to accomplish a 750 km flight.

Overall, I think the key lesson to learn from this flight is this: if I really want to accomplish a 750 km task, I have to take it more seriously.  A 750 km flight requires a different approach than a 500 km flight. In particular, I have to start early enough to have enough time in the soaring day.

My flight track is here.

Attempt #2 – Don’t Waste Time to Get Going!

On June 11 came my second attempt:

  • Start: Bighorn Mountain (2 km east of Gold Hill)
  • TP1: Greenhorn Mountain (60 km south of Cañon City)- 245 km
  • TP2: Crystal Lakes (15 km south of the CO/WY border) – 334 km
  • TP3: Squaw Mountain (7 km south of Idaho Springs) – 130 km
  • Finish: Bighorn Mountain – 43 km

Task Distance: 752 km

This time I launched at 12:14 – about half an hour earlier.  However, I made the same mistake of releasing in the pattern on a convergence day.  I spent almost 50 minutes below 9,000 feet before I finally managed to break free of the inversion and got into convergence lift.

To my credit I went to get a valid start and made an attempt to reach my first turn point.  However, I knew that conditions would have to be extraordinarily strong to complete the task before the end of the soaring day.  I made good progress into a southerly headwind until I got to the town of Victor (south-west of Pikes Peak) where I decided to give up because the remaining 90 km to Greenhorn Mountain were devoid of any clouds.  Instead, a beautiful cloud street beckoned across South Park and so I decided to head west into the Mosquito Range.  I had a nice flight of 533 km and flew above Mt. Bross, my last remaining 14er of the Mosquito Range.

Could it have worked in hindsight?  It’s impossible to say.  John Seaborn had the longest flight from Boulder on that day with 869 km.  This is proof that long flights were definitely possible.  John launched 1:15 hours before me and managed to connect at 11:43 am, 1:30 hours earlier than I did.  As far as I can tell, no pilot flew into the Wet Mountains that day where my first turn point was located. Skysight had predicted some clouds that day over the Wet Mountains and that forecast had not come to pass.

The lessons on this flight are similar to those on my first attempt.  To accomplish a 750k task it is critical to start earlier and to not waste time trying to connect.  An earlier and deeper mountain tow may be necessary, especially on convergence days with a strong inversion over the plains.

My flight track is here.

Attempt #3 – Plan the Final Turn Point More Wisely

Flying out of Nephi, Utah, my third attempt was on July 2:

  • Start: 04 SE Start
  • TP1: 47 King’s Peak (High Uintas) – 171 km
  • TP2: 73 Salina Canyon (along I-70) – 235 km
  • TP3: 52 Mirror Lake (High Uintas) – 211 km
  • Finish: 04 SE Start – 137 km

Task Distance: 753 km

I launched at 12:14 pm (which is fairly early for Nephi – about the equivalent of 11:45 am in Boulder due to Nephi’s westerly longitude) and climbed quickly to 12,000 feet.  I left the climb to cross the start line relatively low.  Unfortunately, I fell out of the band at that point and wasted about 20 minutes to reconnect.  By the time I went out on task it was 1 pm.

My first turn point, King’s Peak (part of the High Uintas), is the tallest mountain in Utah  and it turned out to be a real challenge.  While conditions were great up to Strawberry Reservoir, thermals became narrow and windblown further to the north and only one in three clouds produced climbable lift.  I managed to turn King’s Peak at 2:28 pm but this stretch had been hard work and even with a tail wind, I had only averaged 98 kph.

Just before turning King’s Peak in the High Uintas

Conditions improved once I was back at Strawberry Reservoir and able to connect with the convergence line above the Wasatch Plateau.  My second leg of the flight was into a headwind but I picked up the pace and averaged 110 kph rounding my southern turn point at Salida Canyon at 4:37pm.

Strawberry Reservoir on my southbound leg towards Salina Canyon

The third leg started out really fast (160 kph average with a tailwind) but as I approached Strawberry Reservoir for the second time it was 5:20 pm and I had another 90 km to go to Mirror Lake.  My memories of the difficulties of flying into the High Uintas from earlier in the day were still very much on my mind. As I considered flying into that terrain again at the end of the day I got cold feet – especially considering that I would then have to face a stiff headwind back to Nephi for the final 137 km.

Could it have worked?  Who knows…  Several pilots flew into the High Uintas that day but no one went there so late in the afternoon.  And that is the key lesson of this flight:  do not plan the last turn point such that it is over difficult terrain, far away from home, and facing a headwind on final glide.  Any of these three aspects (difficulty of terrain, distance from home, and headwind on final) can become a problem by itself – all three combined is asking for trouble.  I am glad that I made the prudent decision to give up on this task when I did.  I might have been able to finish, but I might also have landed out at Heber or Thunder Ridge Airpark, running out of lift and unable to get back home.

I took some encouragement from the fact that I had achieved my first two turn points on a challenging 750 km attempt.  My total flight distance that day was 667 km based on OLC plus rules.

My flight track is here.

Attempt #4 – Detour To Follow the Clouds!

Once again flying out of Nephi, my fourth attempt was on July 5.

  • Start: 04 SE Start
  • TP1: xPfeiler Ranch (10 km north of Panguitch) – 198 km
  • TP2: 80 Strawberry Dam (50 km east of Provo) – 269 km
  • TP3: 87 Whiskey Knoll (35 km southwest of Richfield) – 180 km
  • Finish: 04 SE Start – 117 km

Task Distance: 767 km

I launched at 12:13 pm, which should have been early enough for this task, and I had no problem climbing off tow.  The direct route south was blocked by a fire TFR and so I had to go around on the east side of the San Pitch Mountains where I struggled to get up to cloud base and didn’t make good time. Better conditions along the Pavani Range past Richfield and then slow going again past Mt Delano towards my southern turn point.  A mediocre average climb rate of just over 4 kts didn’t support more than 100 kph on that first leg.

A tailwind on the long second leg should have made the going much faster but the air above the Wasatch Plateau had dried earlier than predicted and much of my route was in the blue.  The only visible cloud street was the convergence line east of the Wasatch Plateau, which I (erroneously) believed to be too far off course. Intent on staying high without thermal markers I took a lot of weak climbs such that my average climb rate dropped even slightly below 4 kts. Even with a tail wind, I did not make more than 110 kph on the way north to Strawberry Reservoir.

More blue skies on the way back south against a headwind and my average speed dropped to 91 kph.  This is just way to slow to complete a 750k flight.  Around 6pm the last wisps were gone and it became clear that the soaring day was over.  I made it to the vicinity of Mount Baldy and had to acknowledge that the remaining 50 km to Whiskey Knoll were no longer feasible.

This is at the point when I abandoned my attempt to reach the final turnpoint, Whiskey Knoll, approx. 50 km to the left of the nose. It was 6:34pm.

Crossing the Manti Valley I even dropped below glide range to Nephi but the sun-baked rocks along the San Pitch Mountains provided sustaining lift and ultimately I had no problem getting back home.

In hindsight I should have flown along the convergence that set up over the desert east of the Wasatch Plateau.  I had judged the street to be too far east but looking at others’ flight traces for the day it would have worked very well, supporting speeds of over 160kph and only being a minor detour.  In my assessment during the flight I judged the street too far east and had been concerned about making it back from there to the west side of the plateau.

Here I am flying north along the west side of the Wasatch Plateau en route to my second turn point, Strawberry Reservoir. Note the amazing cloud street to the right, east of the plateau. That street supported average speeds of 160-170 kph, more than 50% faster than my route in the blue.

John Seaborn and Bruno Vassel followed that convergence line all the way to the Grand Canyon and back. John’s distance of almost 1100 km flown at an average speed of more than 150 kph was truly humbling!

The key lesson was that I should have taken the detour to follow the very well marked convergence line where much faster average speeds were obtainable. (The picture above makes this really obvious.)

I managed to fly 709 km that day (based on OLC plus), which was my longest flight up to this date.  Once again I had made the first two turn points and then ran out of time.  I started to feel increasingly confident that it was just a matter of time until it would work.

My flight track is here.

Attempt #5 – Misaligned Cycle Times and Detours

My 5th attempt was back in Boulder on July 9:

  • Start: Ward
  • TP1: Dixon, Wyoming – 200 km
  • TP2: Thunder Butte (10 km south of Deckers, CO) – 285 km
  • TP3: Crystal Lakes (15 km south of CO/WY border) – 190 km
  • Finish: Ward – 88 km

Task Distance: 763 km

This was a cool task because I hadn’t been to the northwest before.  I launched at noon and caught a 10 kt climb right off tow to 17,000 feet.  By 12:30 I had crossed the start line and was underway.

The first leg went quite well and I averaged 100 kph against a solid headwind of 15-20 kts, turning Dixon at 2:30 pm.

Looking northwest into the Great Green River Basin just before turning Dixon, WY – the clouds in this area worked better than they looked.

A tailwind and flying during the peak time of the day should have made my second leg much faster.  However, I got caught in a down-cycle and cloud after cloud dissolved before I got there.  The crossing of North Park was particularly slow going and I took several weak climbs and detours to stay in glide range of Walden.  While my average climb rate had been almost 7 kts on the outbound leg, it dropped to 4 kts on the return resulting in a XC speed of only 105 kph, very poor considering the tailwind.

I returned to the Front Range near Mummy Mountain north of Estes Park and found the convergence line in perfect working order.  Finally I was able to go straight with minimal circling.  Over the following 115 km I averaged 150 kph with convergence lift supporting an effective glide ratio of 117:1.

Turnpoint 2 was to the east of the convergence and harder to get to due to over-development, causing another slow down until I had turned it at 5:15pm. From there I detoured back to the convergence, reaching it by 5:25pm.

By the time I got back to the Continental Divide past Mount Evans it was 5:50pm and the area to the north towards Crystal Lakes was completely over-developed with overcast and rain.

A notable feature of the day were the different characteristics of the various air masses.  The air to the east of the Front Range convergence was quite humid and prone to over-development and showers, whereas the western air was much drier with nice cus, although not always conveniently aligned with my task.

Eight pilots were flying cross-country from Boulder that day and my 685 km flight was considerably longer than anyone else’s. The Cache la Poudre area (where my third turn point was located) was already overdeveloped by 4 pm, meaning that a faster speed on leg two would not have made much difference.

Climbing over North Park just before returning to the Front Range. Cache la Poudre is in front of the nose behind the Never Summer Mountains. Even at 3:50pm this area was over-developed (rain and virga is falling ahead). Two hours later this area was an amorphous grey over-cast and completely unsoarable.

Overall, I believe that a 750 km task was not obtainable that day.  The main lesson to take away is the realization that some great-looking days may simply not last long enough to complete such a long task. 

My flight track is here.

Attempt #6 – When OD Gets Too Much

My 6th attempt was in Boulder on July 17:

  • Start: Boulder (KBDU)
  • TP 1: Centennial, Wyoming (45 km west of Laramie) – 160 km
  • TP2: Scottsbluff, Nebraska – 221 km
  • TP3: Mount Evans – 307 km
  • Finish: Boulder (KBDU) – 61 km

Task Distance: 750 km

I was very excited about the possibilities of this task. Not only was it a 750 km task, it was also a >650 km FAI triangle with start and finish on the same leg. And it would take me across three states – Colorado, Wyoming, and Nebraska.  The cloud bases were projected to be somewhat lower than what I prefer but with much of the task over the eastern plains flying really high was not going to be critical.

The forecast supported an unusually early launch at 10:30 am.  The air was highly unstable.  Cumulus clouds had started to form before 10 am and when I released from tow above the Flatirons at 10:45 am, the first rain drops hit my canopy.

I quickly climbed to 14,000 ft and crossed the start line above Boulder at 11:04 am.  I already had significant doubts about the viability of the task but thought I would give it a try.  Over-development is often confined to the mountains and most of my second and third leg would be over the eastern plains.

At 12:41 I rounded my first turn point at the foot of Medicine Bow Peak.  At 100 kph my average speed wasn’t particularly high but I had been flying into a headwind and it was still early in the day.

Turning eastward it was obvious that the direct route to Scottsbluff was blocked by a big rain cell sitting above the hills east of Laramie.  The shorter detour seemed to be on the northern side but I had not prepared for such a northerly route and wasn’t familiar with the landing areas.  So I decided to try a southerly detour, which would keep me in glide range of Cheyenne and Owl Canyon.

OD and first rain east of Laramie as early as 12:50 pm. My route to TP 2 (Scottsbluff) would have been directly through the rain (left of the nose).

South-east of Cheyenne I had made it past the rain cell and could see a street towards Scottsbluff.  However, looking back towards Boulder, the foothills west of Fort Collins were already heavily overdeveloped with lots of dark clouds and it was only 1:30pm.   Virga and rain had also started to fall from some of the clouds over the plains.

I did  not want to tempt land-out fate and decided to give up on the task and make my way back towards Boulder while heavy rain fell over the foothills west of Carter Lake. Slightly drier conditions to the south allowed me to continue past Boulder and almost reach Mount Evans before returning back home, landing at 3:20pm.

Would a completion of my task have been possible?  I am confident that the answer is no.   Overall there was no new lesson to be learned.  Completing a 750 km flight requires the whole soaring day and if the day gets cut short by heavy over-development there simply isn’t enough time to finish the task.

With 528 km my flight was the longest from Boulder on that day.   My flight track is here.

Attempt #7 – Don’t Take Safety Risks!

Attempt # 7 was on July 31, 2020:

  • Start: Ward
  • TP1: Medicine Bow Peak – 159 km
  • TP2: xBuffalo Drive (south of Hartsel) – 274 km
  • TP3: Colorado/Wyoming Border – 229 km
  • Finish: Ward – 104 km

Task Distance: 766 km

July 31 was a convergence day with a strong ground inversion over the prairie. I launched at 11:15 am and crossed the start line at Ward at 11:51 am at 12,000 ft. While some other pilots struggled to get connected I felt lucky to get underway relatively quickly.

Cloud bases were still somewhat low and conditions relatively soft but I made steady progress, crossing from Trail Ridge Road into the Never Summer Range.   Cloud bases dropped below 16,000 as I headed north but the line of lift was well-marked.  At 1:30 pm I rounded my northern-most turn point above Medicine Bow Peak.

Turning Medicine Bow Peak in Wyoming.

As I began to head back south, some clouds already showed signs of significant vertical development, which did not bode well for the conditions later that afternoon.  But for the moment I enjoyed strong lift of 6 kt average and a glide ratio of 113:1 as much of my leg to the south followed the convergence line along the Front Range and into South Park. My average speed on this leg was almost 150 kph.

Following the convergence along the Front Range. Longs Peak is below and ahead.

By the time I reached Mount Evans, the clouds had begun to darken with clear signs of over-development.  However, the sky ahead into South Park still looked promising and the convergence line extended ahead, fairly well-aligned with my route to turn point 2 south of Hartsel.

Cruising past Mount Evans into South Park. The clouds have intensified but the convergence line is well defined with a clear path to my turn point (and past it towards Salida).

The prudent thing to do would have been to give up at the task at this point. However, the allure of a quick line towards TP2 was very strong.  Having a clear path towards the airport of Salida gave me the confidence to continue.

I rounded turn point 2 at 3:18 pm and turned back north. The clouds had continued to build up but there was a well-marked way back towards Mount Evans and so I took it.

Returning towards Mount Evans across South Park. Boulder is below the dark clouds on the horizon to the right of the nose. These clouds started to trouble me and I began to consider alternative landing sites such as Granby and Kremmling (ahead to the left of the nose beyond the mountain range).

As I got closer to Mount Evans I could see sunshine beyond the virga line ahead.

Snow hit the canopy as I flew via Guanella Pass through some virga west of Mount Evans. Sunshine beckoned ahead towards Georgetown. Boulder is below the big cloud in front. There was very strong lift as I cut through the virga.  I even extended the spoilers before flying across so I would stay at least 1000 ft below the clouds as required by visual flight rules.
Snow and rain fell above Mount Evans. The big cloud on the left towards Boulder worried me more.

At this point it was more than evident that there was no safe way to continue to turn point 3 at the Colorado / Wyoming border.  Heavy over-development and storms blocked the way to the north and I abandoned my task.

At this point my only question was whether to head back to Boulder or to land at Granby, west of the Continental Divide.  After intense radio communications with other pilots I opted for a return to Boulder where the winds were still calm.

However, the final approach towards Boulder was more exciting than I had imagined.  The big cell above Boulder had evolved into a thunder cloud and it’s full extent was difficult to see from my location. But once I had committed to Boulder there was no longer an alternative.   I had to cross below the virga line that marked the storm front.

Lighting flashed overhead just as I was about to cross below the virga line. The Flatirons are ahead to the left of the nose and the path towards Boulder is clear to see. The lightning was a big scare for me and forcefully reminded me to not underestimate the power of nature.

Fortunately there wasn’t much turbulence below the virga line.  I reached Boulder safely and there was little wind on the ground at the time of my landing.  However, I clearly learned a vital lesson: it is absolutely not worth taking safety risks to achieve a sporting challenge.  More specifically: I should have turned back to Boulder an hour earlier – before passing Mount Evans and flying into South Park when I could already have anticipated the possibility of the storm that developed.

My flight track is here.


What did I learn from these failed attempts ultimately preparing me for a successful run:

  1. A 750k is not just a little longer than Diamond distance (500 km).  To succeed you need to take it seriously – in planning, and in execution.  A declared 750k is also a lot harder than an OLC plus 750k; in my opinion it is roughly on par with a 900-1000k OLC plus flight.
  2. You will most likely need the whole soaring day.  This means you have to start as soon as possible and well before the lift is great. You will also still be flying when the lift is no longer great.
  3. Take a higher tow if it allows you to get on task quickly.  If you waste 30-45 minutes trying to connect, chances are that you will come to regret it at the end of the day.
  4. You need a long soaring day. This means conditions should allow for an early launch – ideally before 11am – and last into the evening.  May through August will normally be the only months where such a task is possible, with the best opportunities in June and July – close to summer solstice.
  5. You need a day with reliable weather.  The weather obviously can’t be too stable for the lift wouldn’t be good.  But it also can’t be so unstable for there to be widespread overdevelopment, virga, and rain.  Ideally you want a high cloud base and just enough moisture to generate nice cus wherever you plan your task.
  6. Stay away from days when there is a risk of thunderstorms.  You can fly around localized showers but you should not try to attempt a long task where you may have to fly through lightning, hail, and storm outflows.  Do not take safety risk to achieve a sporting goal.  It is not worth it!
  7. Days with light winds are much better than days with strong winds.
  8. Out and returns or triangle tasks are most demanding but tasks with three turn points give you the best chance to succeed. If you plan a 3 turn point flight the first turn point should be furthest away from the start and turn points two and three should be planned in such a way that the last ~200 km of the flight is relatively close to home.  This greatly reduces your stress level and will encourage you to keep trying until the end.  If the last TP is outside of glide range from your home airfield, you may have to give up early even if there is still a chance to be successful. This is especially true if you are flying above unlandable terrain.
  9. Align the task with the best weather.  Some pilots like to design a few tasks at the beginning of the season and then pick the one that seems best suited for the given day.  The mental exercise of designing tasks upfront can be helpful but you should remain flexible and willing to design a custom task the night before the flight, possibly revising it in the morning to be most aligned with the latest weather forecast.  Take full advantage of the features of modern weather forecasts – especially make sure to use the time slider to determine what parts of the task area are best early, during peak hours, and late in the day. (Forecasts are obviously not always accurate but that’s not a good reason to ignore them!)
  10. Account for the wind when planning your task: ideally use the best part of the day to fly into the wind, and make sure that you’re not fighting a headwind on the final glide home. If there are significant differences in wind speed and direction within the task area, consider them in your task planning.
  11. Be careful to ensure your task complies with all FAI sporting rules (1 km start line, 45 degree turn sectors, valid flight declaration in a valid flight recorder, finish no more than 1000m below the start, etc.) and make sure you observe all air space restrictions including TFRs.
  12. Once underway you must make good forward progress to not run out of time.  Understand what contributes most to a high average speed: (1) continuing forward on task, (2) flying in lift (e.g. along ridges, convergences, cloud streets, or other energy lines – even if it involves taking small to medium detours) and (3) avoiding weak climbs.  Boomer thermals with 10+ kts help but they are not essential.  5-6kt thermals are perfectly fine.  Just try not to put yourself in too many situations where you have to take 1-2 kt climbs.  On a 750k task you will do a lot of circling – 80,000 feet if your average glide ratio is 30:1.  A pilot who always takes 5 kt climbs is much faster than one who alternates between 1 kt and 10 kt climbs.  Do the math of how long it takes to climb 80,000 feet at various different climb rates if you don’t understand why.  If you do a great job following energy lines you may cut the necessary circling down to 50,000 or 60,000 ft – a big time savings!
  13. Make use of water ballast for you will be faster.  Days where ballast is of no advantage are not suitable for 750k tasks to begin with.
  14. There will be segments along your flight where the conditions are not as strong as you expected.  Try not to let that discourage or frustrate you and make the most of the hand you’re dealt with.  While it is unlikely that you will succeed on your first attempt, you might never succeed if you wait for the perfect day when all stars remain aligned from beginning to end.


A Beginner’s Guide to Scoring Well in the OLC Speed League

What Strava is for runners and bicyclists, OLC is for glider pilots: a place where you can upload, share, and compare your flights with those of other soaring pilots. At the end of a soaring day, it’s fun to see where your friends were flying, and to check how you did in comparison.

Such comparison is not limited to a specific soaring site.  With the help of OLC, pilots can analyze their performance against the flights of other pilots nationwide, and even globally.  Weather conditions are obviously very different from day to day and from site to site.  However, over the course of an entire soaring season many differences tend to even out and the overall performances become more comparable.

OLC scores multiple different contests, both at the individual level and and at the club level.  In this article, I want to focus on one specific type of competition: the OLC Speed League.

Final results of the 2019 US Gold League when Boulder finished in third place behind Moriarty and Minden.

The Speed League (the rules are here) has a number of unique characteristics that make it particularly fun and accessible to everyone:

1. It is a team contest that is scored at the club level. On each weekend during the Speed League Season (which normally runs for 19 weeks starting on the 3rd weekend in April), the top flights of three different club members count for the team score in each round.  On some weekends only two or three pilots are available to fly, which means that you don’t have to be an experienced contest pilot to contribute; in fact, every club member has an opportunity to contribute to the club’s overall performance.

2. It’s a great way to practice for soaring contests. You practice flying in less-than-stellar conditions (because every weekend of the season counts, no matter the weather).  You practice all the skills necessary to improve your speed, e.g. quick thermal centering, finding and following energy lines, flying at the optimum speed-to-fly, judging course-deviations, etc.  And you learn to fly with specific goals in mind rather than just meandering around.

3. You don’t have to fly extraordinary distances or get far away from home to score well.  The four fastest legs during a 2:30 hours soaring window count for your flight.  For those flying from Boulder it is often possible to achieve a good score without ever getting out of glide range of the home airport!  Scores are handicapped based on the glider’s performance, which means you also don’t need to have the fastest racing machine. You can achieve a competitive score with any of our club gliders, even the ASK 21.

My club, the Soaring Society of Boulder, has a long tradition of performing very well in the OLC Speed League.  E.g., in 2019 SSB finished in third place among all US Clubs, in 2018 SSB finished second, and in 2017 the club came in first place.

This past weekend was the first of 13 rounds of the (shortened) 2020 season and SSB is in # 1 position of the US Gold League and in #9 position globally – a great start to the season!

Results after Round 1 of the US Gold League for 2020.

To do well as a club, it is critical that enough pilots come and fly on the weekends, especially when the conditions are ok but not great.

In this Beginner’s Guide I am offering 12 tips to help anyone contribute to our club’s performance. These suggestions are particularly geared towards new participants who want to stay within glide range of the home airfield.  But they may also be relevant for everyone else, especially on mediocre days when most pilots will want to stay relatively close to home.

Here’s a link to my first-ever speed league flight attempt in April 2018 at a time when I my total experience was just a little over 100 hours in gliders. It was weak day with low thermal heights over the hills and I wasn’t able to get to the west side of the convergence.  My speed was just barely faster than the required 40 kph minimum for the Gold League but I had the third best flight among those flying from Boulder and the flight earned valuable points for our club.

Some of the tips are fairly specific for the conditions in Boulder, Colorado.  However, many are perfectly applicable to other soaring sites as well, and those that aren’t can be adjusted for typical site-specific conditions.

(1) Be Prepared and Have a Plan

First, look at the weather forecast (I like to use Skysight but RASP is perfectly fine also), and decide whether Saturday or Sunday is the better day.  (Or, if you can fly on both days, your better score will count.)

Once you’ve picked a day, decide on your best soaring window and plan a tentative route based on where and when the best conditions are. Remember that you need to fly up to four (more or less straight) legs over a 2 1/2 hour time period in order to score well.

OLC does not require a flight declaration.  You can simply take off and follow the best lift lines.

However, personally I like to declare a Turn Area Task (TAT) in my flight computer that is aligned with the fastest projected routes for the day.  This forces me to figure out upfront what the best route is likely to be and it is great preparation for contests because I get to practice flying TATs (the most frequently used task type at US contests.)

Skysight has a very handy “Route Forecast” tool that, in conjunction with the “XC speed” screen, is of great help in identifying the fastest projected routes and picking the best start time for the task.

This is a screenshot of Skysight’s “Route Forecast” tool for this coming Sunday (June 7, 2020). Note from the left pane that I have “XC Speed” selected as the underlying display, which shows graphically where the fastest possible flying speeds are predicted. I have mapped out a flight starting at Bighorn Mountain (which is just inside the 15km OLC Start Cylinder), heading first to the south at the edge of the dark red area (just south of Idaho Springs), then heading north over the Poudre, from there back south to a point slightly further east (conditions are expected to be best in that area later in the day), and from there back to Bighorn Mountain. Total distance is 335 km. If I can fly it in 2 1/2 hours that would yield a speed of 134 kph. I can considerably vary my exact route during the flight but it helps to have a general idea where the best potential routes are likely to be. At the top right of the screen you can see a tool that suggests an early start at 10:30AM would yield the best average speed.  The barograph at the top shows the attainable thermal heights, the presence of cumulus clouds, and the heigh of the underlying terrain.  Once you’ve picked a route, you can change the underlying display to take a closer look at additional aspects of the weather along the flight route at any given time (just move your mouse indicator along the barograph slide from left to right to see the changes in the conditions throughout the day).

I usually use three turn areas as this will help me generate four legs.  The minimum task time must be at least 2 1/2 hours but more often than not I plan a somewhat longer task and use a minimum flight duration of at least 3 hours.  OLC will then automatically pick the fastest 2 1/2 hour segment (using four legs).  I keep the radii of the turn areas quite large (e.g. 25-40 km) so I have sufficient flexibility to use the best available energy lines, even it the forecast is considerably off.

For start and finish, I set up a 15 km cylinder centered at the takeoff airport.  This helps ensure that I get a valid start (see tip #3 below).

I can always abandon my task to follow better energy lines once I am underway but I found it much better to have a plan that I can modify, than to have no plan at all.

In addition to having a plan for your flight, also make sure to check for TFRs (temporary flight restrictions), especially during wildfire and football season.  And make sure that you have a valid flight logger and that it is turned on a few minutes before the flight. (It must start recording when the glider begins to move on the ground otherwise OLC will not accept your trace.)

(2) The Most Basic Flight Is Often the Fastest

The most basic (and yet often the fastest) speed league flight from Boulder is a four leg yo-yo up and down the Front Range.  (The entire flight path is often roughly parallel to the Peak-to-Peak Highway.)  Especially good speeds can be achieved if the typical “convergence line” sets up over the foothills. This flight can be accomplished entirely within glide range of Boulder, even on days with modest conditions.

This chart shows a basic TAT for a three turn area flight within glide range of Boulder. You can see the 15 km start cylinder around Boulder. The actual flight will likely start on the western edge of that turn cylinder as conditions are almost always better over the hills. From there it is shown to go south into a wide turn cylinder around Meridian Hill, then north into an equally wide turn cylinder around Lookout Mountain, back south into the turn cylinder around Meridian Hill, and from there back to Boulder.  (It is of course equally possible to start with a first leg to the north rather than to the south.)  Turn areas are set up as “Assigned Areas”, i.e. the actual distance will be calculated based on how far you go into each turn cylinder. You can see at the top right, that the shortest possible task distance is 76.4 nm and the longest possible task distance is 268 nm. This provides a lot of flexibility to adjust the course based on where the best energy lines are.

The basic strategy for this flight is as follows: 

a) Initial climb: After releasing from tow, climb into the convergence (if there is one), or up to cloud base (if there isn’t).  This may take a while and your speed along this stretch is usually poor. Think of the point when you are finally “connected” (with the clouds or the convergence) as the true start of your speed league flight. This is the point when your 2 1/2 window should begin. Make a mental note of the time and your altitude (or write it down on a notepad). (It will be very important that you remember this at the end of your flight!)

b) Pick a Direction for Leg 1: Once you are connected, decide whether to go north or south along the convergence (if there is one) or along the best lift line that you can make out.  (You should already have an idea from the weather forecast which direction will likely offer the better conditions early in the day (e.g. higher cloud bases, and/or stronger lift early in the day). If OD is forecast in either direction, it is usually best to go there first.

c) Leg 1: Follow the convergence (or other energy line) in more or less the same direction (north or south) until you are no longer comfortable to continue or until the conditions get too soft (whichever comes first), then turn around. This will be the first leg of your flight.

d) Leg 2: Your second leg will typically backtrack your first leg although the position of the best energy lines may have shifted somewhat.  Follow the best energy line past Boulder in more or less the same direction and once again keep going until you are no longer comfortable or until the conditions get too soft.  It is likely that the conditions will have improved from the beginning of the flight (higher cloud bases, more cus, stronger lift) so try to go a bit further away from Boulder than on your first leg (provided that you can do so safely). Then turn around.

e) Leg 3: Your third leg will likely mirror your second leg – just in the opposite direction. If conditions allow and you are comfortable, push a bit further than you did on your first leg. Then turn around.

f) Leg 4: Now is a good time to check your watch from the time when you first connected (i.e., the start of your first leg).  If 2 1/2 hours have already passed and you have maintained your direction on each leg reasonably well, you should already have a good score!  However, more likely than not, the 2 1/2 hour mark will still be in the future.  If that’s the case, you should try to get a good fourth leg by backtracking your third leg (and possibly beyond) until the full 2 1/2 hours have passed.

e) Finish: At the end of your 4th leg, make sure to climb up to the altitude when you started your first leg.  (You must be at least as high at the end of your fourth leg as you were at the beginning of your first leg!)

(3) Get a Valid Start

For OLC Speed League flights to count, the start of motorless flight must be within 15 km (9.3 sm, 8.1 nm) of the center of the takeoff airport.

Boulder pilots have all flown on days when there is a powerful ground inversion over the plains and a high tow is needed to get into lift above the mountains. Sometimes that tow will take us beyond the 15 km start cylinder.  (For reference: the top of Bighorn Mountain (west of Lee Hill) is just within the start cylinder, the town of Gold Hill is just outside the cylinder.  Lower Nugget Ridge is inside the cylinder, Jamestown is outside the cylinder.  Bear Peak is inside the cylinder, Gross Reservoir is just outside the cylinder.)

A great way to make sure that your motorless flight takes you into the 15km start cylinder is to set the correct start cylinder on the flight computer.

If you have towed (or motored) beyond the start cylinder you can still get a valid start by flying back into the start cylinder before you head out on your first leg.  To do that, climb high enough first and then come back, “nick” the edge of the start cylinder, and fly back to where the lift is.

This chart shows an extreme example of a “nick back”. It is from this flight last year. The convergence was very far to the west – almost over the Continental Divide – and there was no lift at all east of the convergence. I took an epic tow almost to Idaho Springs where I connected with strong lift. After climbing up high, I “nicked back” into the 15km start cylinder (shown in red), before heading back west to reconnect with the convergence. The yellow arrow indicates the flight path that was necessary to get a valid start for the Speed League.

Getting into the 15km start cylinder after release from tow is critical because your flight will not count at all for the Speed League until your flight path includes a location “fix” within the start cylinder after release from tow.  (This rule is Speed League specific and does not apply for OLC plus.)

(4) On Each of the 4 Legs, Always Fly Forward In The Same General Direction

This should be pretty obvious but it is the most crucial thing to do to get a good result.  Nothing destroys your speed as much as getting low being forced to backtrack to the previous thermal.  You’ll quickly end up with too many short legs and you will not be pleased by the average speed calculation.  If the conditions ahead look weaker, try to stay higher and fly slower.  But move forward whenever it is safely possible and you are fairly certain that you will find lift ahead.

(5) Move On When You Can’t Climb

When I started out I often tried to milk every lift as long as possible.  This meant that sometimes I would keep circling without climbing at all.   Needless to say that I wasted a lot of time doing that.  You only gain distance and points if you move forward, not if you stand still.

It’s also worth considering that you lose a lot of time in very weak climbs.  Whether you can climb at 5 kts or at 10 kts matters much less than whether you can climb at 1 kts or at 3 kts.  Think about it: let’s say you need to gain 3000 ft to close your course.  If you climb at 10 kts it will take you about 3 minutes; at 5 kts it will take you 6 minutes; at 3 kts, you need about 10 minutes, and at 1 kt you need a full half hour!  The difference between climbing 3000 ft at 5 kts and 10 kts is only only 3 minutes.  But the difference between climbing 3000 ft at 1 kt and 3 kts is 20 minutes!

Average climbs tend to be very good climbs overall.  It’s the very weak climbs that will destroy your speed!

(6) Always Follow Energy Lines

“The best speed to fly is the one where you can fly forward on course without having to stop to thermal.” (Sebastian Kawa; watch this video to get Sebastian’s tips on how to fly faster).

One of the great advantages of flying from Boulder is the frequent presence of strong lift lines that allow for straight forward flight without having to stop and turn.  I had already two flights this year where I was able to fly more than 250km in a straight line without ever having to stop to thermal.  Such flights automatically result in excellent average speeds even if your cruise speed isn’t particularly fast per se.

If there are well-marked energy lines such as this convergence line, you can achieve high speeds by flying straight over long distances without having to stop and circle.

Let’s say you’re cruising in a club Discus at a modest indicated airspeed of 65 kts.  If you’re flying at 15,000 feet, your true airspeed is 84.5 kts!  Even if you’re loosing as much as 20% due to some course deviations and having to crab into a cross wind, your ground speed  is still 67.6 kts (125 kph).  And if you don’t have to stop to circle, that speed will be your average ground speed.  If you can maintain this way of flying for 2 1/2 hours you will achieve 117 pts for the speed league (125 kph / 1.07 (Discus Handicap)).  Not bad!  And you can obviously do even better if you fly faster through any sink and slower through areas of strong lift.  Three flights like this on a particular weekend will inevitably guarantee your club a top result in the Speed League!

If you look at flight traces of fast flights, you will often see that they are not directly straight. This chart shows the trace of my flight on May 31, 2020 where I flew over 200 miles without a single circle. I highlighted one of the legs in yellow but you can look at each northbound and southbound leg and see that the trace weaves along the convergence that had set up parallel to the Continental Divide. The line isn’t exactly straight because the divide isn’t exactly straight either. Also, the heights of the peaks along the divide varies as well, which causes the strength of the westerly wind to vary, thereby shifting the line further to the east or further to the west.

In Boulder, the most frequent and most reliable energy line is the convergence line that sets up when there is a westerly airflow aloft coming across the Continental Divide, and thermals over the foothills generate an easterly airflow over the plains.  Read this article to learn more about how you can climb into the convergence, identify it, and follow it.  For Boulder pilots, being able to locate and follow the convergence is perhaps the single most critical skill to achieving good speed league results.

During the summer season we also often see powerful thermal streets setting up, e.g., over the Poudre, into South Park, and west of the Divide towards Kremmling and beyond.  In spring, fall, and winter wave conditions may create even more powerful energy lines.

Look for such energy lines (especially convergence) in the weather forecast and then seek to follow them during your flight.  The better you’re able to do that, the higher your average speed will be.

A convergence line often sets up on blue days as well.  It is then obviously much more difficult to locate but there are great rewards if you can find and follow it.  Certain flight computers (e.g. the Naviter Oudie) will allow you to download the weather forecast before your flight and display the projected location of the convergence line at the correct time while you’re flying.  Provided that the forecast was accurate, this can be of great help!

(7) Stay in the Lift Band

In Boulder we frequently benefit from high cloud bases.  In fact, the bottom of the clouds is often 10,000 feet above the ground, sometimes even more.  Things are often great when we can cruise under clouds.  However, everyone has experienced that getting “connected” with the clouds can sometimes be quite difficult and take a while.  To achieve high speeds we have to be careful not to lose the connection once we’ve made it.  Otherwise, if we “fall out of the band”, we have to go through the time-consuming process of working our way back up again. Needless to say that this will negatively impact our average speed.

When you are “connected” with the clouds, western soaring conditions can be incredibly strong. Here I am cruising at >110 kts at 17,000 ft under a cloud street on a flight on June 5 2020. 20 minutes later I made a mistake and let myself drop below 13,000 feet over the Poudre. At that time it was almost game over and I had to work very hard to prevent a land-out or a motor start.

It is not always easy to determine how deep the good lift band is.  If you divide the distance between the ground and the cloud base in thirds, a rule of thumb is that the upper third almost always works and the lower third is almost always difficult.

E.g., let’s say the cloud base is at 16,000 feet and we’re flying over the foothills over terrain that is at 10,000 feet.  The altitude band between 14,000 and 16,000 tends to work best and the band between 10,000 and 12,000 ft is likely very challenging.  The area between 12,000 and 14,000 is the “murky middle”.  On some days, conditions are great, or others not so much at all.

E.g., this past weekend, cloud bases were around 15,500 ft and I struggled mightily until I broke through 13,000 feet.  From then on I managed to stay high and did not test the lower sections of the band.  Looking at the traces from other pilots suggests that conditions improved in lower levels and that good lift could later be consistently found even at only 12,000 feet.

I tend to err on the cautious side and stay relatively high at the expense of climbing more often in less than optimal lift.  Others are more aggressive, stop less frequently, and assume a greater risk of “falling out”.  On some days one strategy works better than the other and luck can also be a factor.  If you’re relatively new to cross-country flying you’re probably better off with a somewhat more conservative approach: more altitude gives you more options to find good lift, reduces the likelihood that you have to waste time digging yourself out, and also minimizes your land-out risk.  You might not be the fastest but you will be more consistent and sometimes just as fast as those who push their luck a bit more. Your flight will also be a lot less stressful.

(8) Successfully Cross Blue Gaps

When I started to venture further away from my home airport, I was very concerned about blue gaps between clouds. When I came to the end of a street with a 5-10 mile gap ahead of me I often got cold feet and turned around.

The problem is that crossing blue gaps is often inevitable if we want to score Speed League Points (or fly XC in general).   Otherwise we may end up with too many legs over the 2 1/2 hour scoring window.  I.o.w., our best four subsequent legs won’t add up to a lot of miles even if we otherwise had a good and fast flight.

Blue gaps can be tricky like in this picture taken south of Granby heading west. Don’t just head straight to the next good looking cloud. Always look for small wisps above and fly exactly underneath them as you fly towards the nice cloud. Chances are good that this will allow you to arrive much higher at the cloud than if you had flown straight.

So how can we deal with blue gaps?

First, we should always look ahead so that we are not caught by surprise when we come up to a blue gap. The last cloud in a street may not work so well, so it is always a good idea to get close to cloud-base well before we reach the end of the street.

Second, we should assess the nature of the gap as best we can.  Does the gap mark an area of sink or is the air just dryer?  This may not be obvious but it is always a great idea to look for any kind of cloud activity.  Often there are tiny wisps across the gap and those are usually a good indication that we won’t fall out of the sky if we follow those wisps.  E.g., along the convergence it is fairly common (especially early in the day) that we run into areas with lower moisture but the convergence line is not interrupted at all.  We have to look for any signs of clouds across the gap, connect the ones we can identify into a line in our imagination, and then fly along this imaginary line just as we would if the gap did not exist at all.  More often than not, this works much better than we think!

Third, if we’re not confident that an existing lift line extends throughout the gap, we should treat the gap as a “transition”.  This means we should start high and “downshift”, i.e. fly more conservatively if there is a risk that we might get to the lower end of the lift band.  We must still accelerate through sink and slow down in lift but we should fly less aggressively than we would otherwise.  E.g., if we used MC 5-6 before to determine our Speed-to-Fly, we may decide to now use only MC 2-3 until we are confident that we are able to connect with stronger lift on the far side.

Fourth, a good way to monitor our glide performance throughout a gap is to set up a NAV box on the flight computer that shows the Current L/D.  I find this a better way of understanding the actual glide performance that I can achieve through the gap.  Understanding this is especially important in case I have to decide to turn around and fly through the same air again.

Fifth, if the gap is so wide that we don’t know for sure that we can cross it successfully we should decide upfront at what point we will abandon our attempt and turn around even if it means that we won’t achieve a good speed-league score. E.g., let’s say we want to make sure that we stay within glide range of Boulder.  In that case, we can set Boulder as our “Go-to” airport into your flight computer even if we’re heading away from it.  We should use a safe MC setting (i.e. one that is relatively high, let’s say 4 or 5, and keep track of the arrival altitude on your flight computer so we can turn around before we get out of glide range. (Also we must always make sure that we have set an appropriate arrival altitude.  The club recommends 1,500 ft AGL so we have an extra cushion and can still fly a normal landing pattern even if we encounter some sink.)

(9) Thermal Strategically

Every textbook on gliding has good tips about thermal centering and I won’t repeat those here.  It goes without saying that flying consistent, well-coordinated 45-degree bank circles at a consistent airspeed is a critical skill that we all must practice over and over again.  It’s also self-evident that we will do much better if we only stop for stronger thermals, center them faster, and continuously adjust our circles so that we are in the best area of lift.

In addition to these “standard rules” here are a few tips that are more specific to our conditions.

First, if in doubt, turn into the wind.  The best thermals are usually on the upwind side of the convergence line.  When we follow the line, we necessarily fly in a cross-wind (usually out of the west).  That means that on northbound legs we should typically turn left if we stop to climb, and on southbound legs we should typically turn right.  There can be exceptions of course but they tend to imply that we did not fly along the optimal line to begin with.

Second, observe where the best lift can be found under clouds.  The best lift tends to be on the upwind side and/or the sunny side. Fortunately for us, typical Boulder conditions mean that wind and sun tend to be fairly aligned with westerly winds aloft and the sun in the afternoon in the south west.  So more often than not, the best lift is in the south-west corner or along the western edge of the clouds.  However, if you notice it to be different on a particular day under one cloud, check if that is true for the next cloud as well. Chances are good that it is.  E.g., at one of my flights this year there was a 20kt wind from NNW and the best lift was consistently under the NW corner of the clouds.

Third, large clouds often have multiple cores.  If you find lift under a big cloud this does not mean that you have found the best lift under that cloud.  The best lift can be on the upwind/sunny side or underneath the darkest, flattest (or even concave) portion of the cloud. It makes a big difference to your overall speed whether you thermal at 2-3 kts or at 7-9 kts.

Fourth, if the lift is very strong under a cloud street, fly 1500-2000 feet below the cloud bases.  This way you can pull up in strong lift and fly faster through areas with weak lift or no lift. If you’re too close to cloud base, you’re forced to fly fastest through the strongest area of lift (so you won’t get sucked into the cloud) and fly slower through areas of weak lift or sink.  It should be obvious that the first technique will result in higher speeds.

Fifth, in strong positive surges it pays to turn into the wind and gently pull up (using the flaps if you have them).  If the surge persists, you can then bank steeply and might get the core on the first turn.  If the surge goes away quickly you can turn back on course and pick up speed again without loosing a beat.

Sixth, remember that it is always the weakest climbs that destroy your speed.  If you take all the climbs that are average or better you might not be the fastest of the day but you will do very well because you drastically reduce your risk of having to dig yourself out from down low in very weak lift.

(10) Optimize Course Deviations

Notice that I did not say “minimize” course deviations.  Flying straight is obviously the shortest way to go but very rarely the fastest.  If you can follow a lift line without having to stop and turn, course deviations of up to 30 degrees will almost always pay off.   (John Cochrane showed that a 30 degree deviation implies a detour of only 13%.  Smaller deviations have minimal negative effects.)  If there is a strong convergence, you may sometimes need to make deviations of 40 degrees from the course line and it will often still be be better than flying straight.

During my Diamond Distance flight last year, a convergence line near the end of a long soaring day saved my flight.  I was very happy to follow it despite a 40 degree course deviation.

(11) Strategically Decide When To Change Directions

The most important factor to scoring well in the Speed League is to not have more than three major course changes over the 2 1/2 hour soaring window so we generate four more or less straight legs.

Our best strategy is to follow a clear lift line for as far it is working well and to turn around and use the same line in reverse.

Sometimes we get to the end of the lift line but are in need of more miles in the same direction.  In this case it makes sense to stop in the last good lift, climb up high, continue in the same direction even if it means flying in no lift or slight sink and turn around at a point that will still allow us to get back to the same climb that we left before.  E.g., sometimes, going northbound, the good lift line will stop north-east of the Twin Sisters but we may need more northbound miles otherwise our leg is too short.  In this case we can take a high climb east of the Twin Sisters, head out further north (often in the blue), and then turn southbound in time to have enough altitude to connect with the climb that we previously left.  (We may also find out that we’re able to connect with the next lift line and continue further north over the Poudre.)

If there is a strong headwind or tailwind component, another tactic is to change course direction when we are low on an upwind leg, and when we are high (e.g. right after a climb to cloud base) on a downwind leg.  This way we benefit from the wind drift while climbing in both directions.

(12) Climb Back Up At the End of Leg 4

I already mentioned that the end of your 2 1/2 hour scoring window must be at an altitude equal to or higher than your altitude at the beginning of the scoring window.

This is very easy to overlook and a frequent cause for an unnecessary loss of Speed League points.  Hence it is very important to remember how high you were flying during the early parts of your flight and that you climb up to your low points during those early parts of the flight.

Pilots who’s flying style involves a lot of climbs and descents tend to have less of an issue with this rule than pilots (like me) who tend to stay relatively high.  If you go on Final Glide after TP 3, the portion of your last leg that is below the altitude at the point when your scoring window started, will not count for the Speed League!

Bonus Tip for OLC Plus Scoring: If you climb up high at the end of your fourth leg you will not only make your fourth leg count, you can then also use the extra altitude to turn your flight into a bonus triangle.  (This will count for OLC Plus but not the Speed League.)  To do that, head out into the plains to the edge of Class B airspace and then return back to the point where you released from tow to close your triangle.  (To close the triangle you do NOT need to be at or above release altitude.  You just need to cross any previous portion of your glide path that is necessary for your triangle to be “closed”.)  If you succeed in closing the triangle you will get 1/3 of your FAI triangle distance as bonus points for OLC Plus scoring.  (Note: This may not be practicable on days when you released far west and never had a trace near Boulder.  It helps to display the full trace of your flight on your moving map screen (and not just the last few minutes) so that you can easily locate the best place to close the triangle.)

Be Safe and Have Fun

Learning to fly competitively focuses your brain and is a lot of fun.  However, it must never mean that you relax your personal safety standards.  Do not become single-mindedly focused on optimizing your score.  Safety must always come first.  Always maintain a Plan B and a Plan C if Plan A does not turn out as you hoped.  If you can’t get a great score on a particular day you can learn from your mistakes and try again on another day! Not so if you ruin your glider or even your health.

Be safe and have fun!

Climbing Into the Boulder Convergence

This past Saturday we had another textbook convergence line form above the foothills west of Boulder.  Climbing into convergence was quite tricky – as it often is – but there are amazing rewards for those who can make it.

I was able to video tape my flight and since there were outstanding markers that showed exactly where the convergence formed, I thought I would put together some in-depth explanations for how to get there and how to follow the lift line once you’ve made it.

You can find all of that in the following video:

In addition, I have tried to summarize 10 key lessons for flying in Rocky Mountain convergence lift from Boulder.

(1) Find a good climb after releasing from tow and climb as high as you can.

If your first climb takes you to 14,000 feet you are probably already set and can head straight to the convergence.  However, on most convergence days, the thermals east of the convergence line will top out at much lower altitudes.  Above the lower foothills it is common that the lift will only extend to about 1,000 – 3,000 ft AGL.  It is therefore very common that your first climb may only take you to 8,000 or 9,000 ft MSL.

On Saturday there was no ground inversion and I was able to release in good lift right above the airport and climb up to cloud base, which was at 10,000 feet MSL.

Note: when there is a ground inversion over the plains there might not be any lift near the airport. If that’s the case you probably need to take a mountain tow to get into the first good thermal that can take you to cloud base.

(2) Once you’re at cloud base, head west towards the hills and look for lift that can take you a bit higher.

The goal is to get high enough to reach the convergence line.  How high you have to get depends on where the line is located and, therefore, what altitude you need to get there safely and be able to return to Boulder should you be unable to connect with lift.

If the lift tops out relatively low to the ground (at about 2,000 ft AGL or even lower) you will likely need multiple climbs as you head west.  Each climb is likely to take you a few hundred feet higher, commensurate with the increase in altitude of the terrain below.  E.g. 2,000 feet above Nugget Ridge will take you to 9,200 ft.  The same altitude AGL above Gold Lake will take you to 10,600 ft.

The convergence line might be as far east as the first hogback or it might be as far west as the Continental Divide itself.  The altitude needed to reach it safely obviously differs greatly based on how far west the line is located. Most of the time, the line is within a few miles (east or west) of the Peak-to-Peak Highway.

Weather forecasts can help you determine where the line is likely to be.  E.g., Skysight has a dedicated page for Convergence and will predict the location of the convergence line throughout the day in 30 minute intervals.  You can get essentially the same information by looking at vertical velocity on the RASP forecast. Note, however, that the position of the convergence is notoriously difficult to predict so expect the forecast to be off by several miles.

On Saturday, I found a climb over the foothills to the northwest of Gross Reservoir under a cumulus cloud that took me to cloud base at about 11,000 ft MSL.

(3) Look for markers that indicate where the convergence line is likely to be.

The convergence may or may not be marked.  Blue days are difficult because the line can be very hard to find and following it is also very challenging.  If there are no clouds at all, all you may have to go by is the “feel of the air.”

More often than not, there are at least some cloud indicators that show the position of the line. However, they are not always as easy to spot as this past Saturday.

This is what the sky looked like when I left my climb at Gross Reservoir at 11,000 ft MSL and continued to head west towards Nederland (at the right edge of the picture).

  • Overhead on the left of the picture are remnants of the cumulus cloud that marked the thermal I just left.
  • Left of the nose (towards Thorodin Mountain) are additional thermal-marking cumulus clouds, which have a similar base as the cloud that I’m just leaving.
  • But the most interesting clouds are the scraggly-looking clouds further west. In addition to their different shape and appearance you can also notice that the base of these clouds is considerably higher.  They are not ordinary cumulus clouds but are “curtain clouds” marking the location of the convergence.

Confronted with the situation shown in the picture above, it is evident that I have some ways to go before I reach the convergence.  (The curtain clouds appear to be further west than Nederland although differences in distance between clouds and ground features can be hard to judge.  Looking for cloud shadows may help make this assessment.) Also, it is critical to consider that the lift will not be directly underneath the curtain clouds but to the west of them!

(4) As you head further west, pay very close attention to any lift or sink and commensurate changes in your altitude and formulate a Plan B and a Plan C in case you don’t find the expected lift.

Knowing where lift and sink are can become critical if you are not successful finding a climb and have to head back east.  On days with sink you will need a much bigger safety margin than on days when the air is generally good.

In this picture I am now west of Nederland and rapidly approaching the curtain clouds.  Note that I am at 10,700 feet.  This feels quite low for the location where I am flying and I am mentally prepared to turn around immediately should I hit any sink.

However, I draw some reassurance from the fact that I only lost 300 feet since leaving the cloud near Gross Reservoir – seven miles further east.  The rim of Boulder Canyon is at 8,500 feet – this means that even if I lost more than 1,000 feet heading back east , I would still be more than 1,000 feet above the Canyon rim.  On some days (e.g. west wind days with the potential of wave or rotor) this would not be an acceptable margin at all but given the specific conditions of the day I decide to continue towards the west side of the curtain cloud and pledge to turn around as soon as I drop below 10,500 ft.

Note: I find it very important to always consider my safety margins well before approaching a critical decision point. Key factors that go into the decision are (1) the day’s conditions, (2) my skill, experience, and recency level, and (3) the performance of the glider I’m flying. I like to set hard rules for myself before approaching a somewhat marginal situation so that I won’t hesitate to take action before the situation becomes unsafe. (I also had a Plan C – to land at Caribou Ranch – in the worst case scenario of hitting substantial unexpected sink on the way back east.)

(5) Know where you need to be to connect with convergence lift.

The following sketch illustrates how I think of the process of getting connected with convergence lift.

The glider is approaching from east to west.  It climbs in thermal lift (shown in red) under a cumulus to cloud base somewhere over  the foothills.  From there it keeps pushing further west in the hope to reach the convergence lift (shown in green).

The scraggly curtain cloud is shown to the east of the convergence lift.  The curtain cloud always forms at the edge of the two air masses.  The eastern air is typically more moist than the western air.  Therefore the cloud forms on the eastern side.  The best lift is always west of the curtain cloud because the curtain cloud forms where the eastern airmass blocks the dryer western air from advancing east.  I think of the curtain cloud as a barrier for the westerly wind: the west wind has to move up in front of the barrier almost like it has to move up along a mountain slope when you’re flying in ridge lift. (This isn’t entirely correct because the eastern airmass is obviously not as solid as a mountain but this model is very helpful in establishing a mental framework for what’s going on.)

Note that convergence lift is very unlikely to come up from the ground because it forms as a result of two wind streams coming together.  At ground level there is too much friction and turbulence to form usable lift.

This means that the key to connecting with convergence is to be high enough to get into the (green) convergence zone.  If you’re not high enough you will not find a climb.

It is therefore important to take every opportunity to climb as high as possible when you are close to the convergence.  In the illustration I have shown a thermal (in red) just below the convergence lift.  The glider enters the thermal and climbs up to the top of the thermal.

You’ll often notice that at the top of the thermal the lift becomes very weak and unorganized because it gets sheared off by the west wind and and the air becomes more turbulent.  But very often you are now right at the cusp of making it, and with a little bit of luck you can continue your climb into the convergence.

When you analyze your flight afterwards you’ll notice that the wind drift in your climb changes half-way through.  As long as you were in the thermal, you kept drifting from east to west and as soon as you enter the convergence lift, the wind drift changes from west to east.

In the picture above I am approaching the top of the thermal that is right below the convergence.  The wind drift is still from east to west.  Seconds later, the climb rate weakens as wind shears the thermal off.

In the post flight analysis you can recognize the change in the wind drift half-way through the climb.  (You can best see this on the left side of the chart above that shows a 3D image of the climb.  Note how I drifted from left to right (east to west) in the bottom half of the climb, and how I started to drift right to left over the past three circles.)

(6) Be careful to conserve and top up altitude until you are solidly connected.

The illustration above has shown why a minimum altitude is critical to reach the bottom of the convergence.

One complication can be that the first contact with convergence may not be good enough to let you climb much higher.  If that is the case, you need to explore nearby to see if you can gain more altitude before you start to fly along the convergence.

If the convergence line is marked by clouds this should not be too difficult.  Look for any signs of air moving up and make your way to the upwind side of such markers.

In the picture above I am heading to the upwind side of the curtain cloud just to the left of the nose.

I turned as soon as I found lift and climbed up to 14,000 feet MSL.

You can now see that the wind drift is much more significant and firmly from west to east.   This is a clear sign that I am now established in the convergence.

(7) Once you’ve made it, everything becomes easy: just follow the line on the upwind side!

Depending on the strength of the convergence, you may be able to cruise fast in straight flight without circling at all.  Always stay on the upwind side of any marker clouds!  If the convergence softens, you may need to decrease your cruising speed, and if the convergence is weak or if there are big gaps in the line you may need to stop in stronger lift from time to time to top up altitude.

In this picture I am cruising northbound along the convergence from Mount Evans to Longs Peak.  I flew the entire ~45 mile stretch without a single circle and lost only 2,300 feet – an effective glide ratio of almost 100:1 at about 80-90 kts.  Not bad!

(8) Make sure you don’t fall out of “the band”.

We’ve discussed earlier that convergence typically does not reach all the way to the ground.  Therefore you must maintain a minimum altitude to stay in convergence lift.

The flying technique is similar to flying in ridge lift.  The best lift along the ridge tends to be at ridge top – not higher and not lower (unless there are differences in the steepness of the slope).   In convergence lift there is obviously no visible ridge top but I found that the lift tends to be best somewhere between the bottom and the top.  It rarely pays to fly at the top of the lift band because the lift tends to be weaker.  And you have to be very careful not to drop too low and fall out of the band!  (If you do, you have to begin the process of climbing up into the line all over again.  This is likely just as difficult and time consuming as it was when you entered the line and if the conditions change it might even become impossible.)

Be particularly careful if there are big gaps in the line of curtain clouds. Sometimes such gaps are just the result of reduced moisture and the convergence lift continues unabated between the clouds.  But sometimes gaps can also mean that the lift line itself is interrupted.

Approach such gaps with some caution and think of them as transitions, just as you would approach gaps along a ridge line.  You do not want to keep pressing ahead at full speed and then arrive at the next marker cloud too low to reconnect.

(9) Watch the lower lying clouds and always maintain an escape route

Flying in convergence may allow you to fly much higher than the cloud base on the downwind side.  In this sense, it is similar to flying in wave.  Always observe what is happening below you, especially if the cloud layer is becoming thicker and more dense.

On Saturday, the convergence line moved further west during the day and ended up directly above the spine of the Continental Divide.  At the same time, upslope conditions over the plains caused increasing low level clouds to the east.  When the sky to the east looked like this I decided it was time to pull out the spoilers and begin my descent below the lower lying clouds to the east.

(10) Have fun and fly safe!

Convergence conditions offer some of the most rewarding soaring in Boulder.  Flying in convergence is easy and fairly safe provided you stay away from other aircraft (a transponder and Flarm are highly recommended).  However, as discussed earlier, getting into the convergence can be fraught with risks – especially if the convergence line is west of the Peak-to-Peak highway and the thermal lift to the east of the line does not extend much beyond 11,000 feet.

I’m always trying to set safety margins that are appropriate for my skills and experience, the performance of the glider I’m flying, and the conditions of the day.  A large percentage of accidents happen because pilots delayed a critical decision and found themselves in situations that simply offered no safe way out.  Know your margins and always maintain a Plan B and a Plan C that you know you can execute safely if necessary.

My flight track is here.

A link to the video of the flight (with explanations) is here.