Following the All-Important Line

In my previous post I explained why – on some days – cross-country flights from Boulder are only possible by locating and connecting with the prevalent convergence line that often runs parallel to the Front Range of the Rocky Mountains.

Beautiful view of Boulder from Gross Reservoir. Note the low hanging clouds east of the convergence.

Yesterday was another “line-day” even though the line wasn’t nearly as pronounced or critical as on April 27.

Thankfully the line was much further east than on April 27, just a few miles into the foothills, and it was possible to tow right into it.  The day provides a great example of why good XC speeds can only be achieved by recognizing and following the best energy lines.

A dense cloud layer sat on top of the divide all day. This was indicative of the westerly flow that pushed humid air up on the west side of the mountains. On the east side (i.e. the near side of the mountains), a largely cloud-free zone formed. This is most likely the result of air warming up as it descended in the lee of the mountains, forming a Föhn gap just like on typical wave days. The small scraggly looking clouds above the peak-to-peak highway were most likely rotor induced.

This, of course, is not a new insight.  20x world-champion, Sebastian Kawa, said in his recent interview with Bruno Vassel that “where you fly, i.e., the line you choose, is the most important factor to winning”.  In a recent webinar, former US team captain, John Good,  compared soaring to running through the woods: “the fastest way is to follow the path” instead of “crushing through the undergrowth”.

Being a trail runner myself, I love John’s example, but I would also say that a runner’s paths through the woods are usually a lot easier to locate than the energy lines through the sky.  Successful cross-country soaring therefore often comes down to the art of recognizing and following these paths.

Unlike a well-trodden hiking trail, the path through the sky is – by itself – always invisible.  However, on many days clouds can provide excellent markers that, akin to trail blazes, help you find the route even if the trail itself is completely snowed in.  And just like trail markers, the identifying cloud markers can sometimes be spaced close together, and sometimes they can be far apart, making it easy to get lost.  And sometimes there are no markers at all.  Such blue days are the hardest because you are left to using your analysis of the wind, the sun angle, and the terrain, and your imagination of what is happening in the sky, to figure out where the energy lines would most likely be.  (However, it’s important to recognize that – unless the air is completely still – they are almost always there.)

Clouds are like trail blazes that help you find the path through the sky even if the trail is completely invisible.  How would you know where to go if it weren’t for this marker?

But back to yesterday’s soaring.  The screenshot below shows the flight traces of the four Boulder pilots who posted their flights on the OLC web site. The first thing you’ll notice is that each of them tried to follow the energy lines that set up parallel to the Front Range due to westerly winds coming over the mountains and a weaker easterly flow near the ground over the plains.  Where these flows came together, i.e. converged, the energy line(s) set up.

Flight traces from the 4 Boulder flights posted to OLC yesterday. Finding and following the energy line(s) was critical to good XC speeds.  My trace is shown in green.

I’m using the plural because there wasn’t only one line.  You can see this in the northern half of the chart where there was more than one line that provided lift.  I believe that this is due to a weak wave motion of the westerly flow aloft which tends to result in lift lines underneath each wave bar.  Consider the drawing in my prior post.  I think it is the most likely explanation for this phenomenon.  In the southern half of yesterday’s soaring area the line was most distinct and you can see that all pilots flew within the same narrow lift band.  (The traces are basically overlapping.) The small east-west variation of the flight tracks here is most likely the result of the line shifting slightly over time and each of the pilots flying there at somewhat different times of the afternoon.

There were a lot of clouds yesterday and for the most part finding and following the line was relatively easy.  The most tell-tale sign was the dramatically different height of the cloud bases.  Cloud bases to the moister east of the main energy line were much lower than on the drier west side.  Curtain clouds were a frequent occurrence marking the edge of the line.  It was always critical to stay west – on the dry side – of the curtain.  (You can also take a look at this flight from last year for more pictures and narrative about following the convergence.)

Cockpit view of the convergence line near Button Rock Reservoir heading south. Disregard the reflections on the wind shield and notice the difference in the cloud bases and the scraggly looking curtain clouds to the left. The best lift tended to be along the clouds with the highest bases and the flattest bottoms, usually below the western part of these clouds, often just along their western edges. The lift could be very strong, frequently topping 10kts. (The highest reading on my vario showed 18kts of lift!)

The line was at times quite narrow.  I.e., you could find very strong lift following along the line but it wasn’t always possible to circle within the lift without falling out of it on one side of the circle.  The best strategy was to just slow down to minimum sink speed when flying in strong lift, and to push the nose down wherever the line was broken.

Intense sunshine hitting the foothills in the afternoon also caused clouds to form further west of the main energy line and this could be quite confusing.  It was as if some prankster had put up a few erroneous markers in the woods to the side of the trail.  If you were tempted to follow such a side trail  (as I was two or three times) you would still find lift but it was much weaker than along the main energy line.  But even worse, eventually the side trail would end and you would have to fly back to the main energy line.  And there you would be punished by having to cross severe sink causing a tremendous loss of height, i.e. potential energy.  (This was just like the time lost by a runner who erroneously followed a random animal track and then has to bush-whack their way back to the real path.)  Very clearly, the pilots who avoided such temptations and stayed right on the line posted the highest speeds.

You can see that during some portions of my flight I did this better than at other times by looking at the average speeds for each of my four flight segments.

On my first leg my average speed was 110 kph.  I did a pretty good job following the line but had started off conservatively and flew at modest airspeeds.  I also gained 4,000 feet on this leg so this was a pretty respectable start.  I then did a little worse on my second leg.  The speed is almost identical but without a net gain in altitude.  However, I was now flying into a headwind component.  A close look at my flight trace shows one erroneous route deviation where I followed a side track that led me a few miles too far west and eventually caused me to loose more than 2,000 feet to return to the main line.  The third leg was my fastest with an average speed of almost 135 kph even with a slight net gain in altitude, showing that the day had great potential.  I don’t think there were any blunders during that leg.  And then came a disappointing 4th leg with an average speed of only 78kph.  Once again I flew a route a little too far west when I lost almost 3,000 feet and was forced to take a rough and uneven climb, only to be tempted once again to try out another line further west, which did not work either.  (At this point I should have had learned my lesson!)  Without these mistakes I could have posted an average speed of well over 120 kph for the entire flight.  PB and CX demonstrated that this was clearly possible.

After completing the 4 speed-league legs and before coming to land, the best line had shifted further east and demonstrated the potential for even higher speeds later in the day when  I flew from Lyons to Eldorado Springs, a distance of 30 kilometers, at an average speed of 182 kph while only losing 1,000 feet of altitude.  (Unfortunately this leg did not count for the speed league because my altitude was too low.)

View from Gross Reservoir towards Barker Reservoir and Eldora ski area towards the end of the flight. The cloud in the foreground is a regular cumulus.  (It is a few miles west of the convergence line and likely provided only moderate lift.)   Behind is a a row of small rotor clouds (which provided no usable lift). The cap cloud over the divide seemed to have separated from the peaks, possibly by air drying out and some thermal lifting as the sun came through. There may have still been some wave motion aloft (responsible for the rotor formation), but probably streaming at higher altitudes and inaccessible by glider. [Note: this is a somewhat speculative interpretation. Please let me know if you think that it’s not correct.]
The flight track is here.

Lessons Learned

  • If you can recognize the line, stick with it.  Don’t be tempted by clouds that make you deviate from the main line.  They may just lead into a cul-de-sac and you may have to “bush-whack” your way back to the main path, losing a lot of altitude in the process.
  • The line can be narrow. On a few occasions when I tried to circle in 10+ kt lift I found that the line was too narrow to stay in good lift throughout an entire turn.
  • Circle as little as possible, ideally not at all.  This flows from the above and it requires the following.
  • Fly a precise line.  Kawa emphasized this in his interview with Bruno Vassel.  Especially when the best lift band is narrow, it is extremely important to fly in the right place and not 500 feet too far left or too far right.  (You would not want to run through the woods 5 feet to either side of the trail either.)  Of course, that is much easier said than done.  Observe throughout the flight where the best lift is relative to the clouds and plan/adjust your flight path accordingly for the clouds ahead.  If you hit strong sink between clouds (or if there are no clouds), chances are that you are too far left or too far right and need to change direction.  Don’t just hold the course and hope for the best. If in doubt, try upwind first, then go downwind.
  • Fly at the right speed. Maximize your time in the best lift to fill up the altitude tank as much as possible, and then push through stretches where the line may be broken.  This means looking ahead and planning to fly just above stall speed through stretches of best lift, and accelerating before likely stretches of sink.
  • Remember the altitude rule for the speed league. After a particularly fast stretch of flight, you must climb back up to altitudes earlier in the flight to make the segment count.


Why Did I Miss The Line?

Yesterday, CX scored 350 km in 2.5 hrs for the OLC Speed League, commenting, “today was probably the best cross country day out of Boulder since last September.  The convergence was strong and well defined to the North and workable to the South.  Unfortunately there was only one flight posted for League scoring.”

I had a fun flight too, but it was all down low and in terms of league scoring? – Nothing! And it’s not that I didn’t try. So I thought I’d try to look at my flight versus CX’s and find out what happened.

First, let’s recap the conditions. There were very strong westerly winds coming across the Continental Divide. And there was a weaker easterly flow approaching the mountains from the plains. (You could see it at the airport in the morning: there were low clouds moving westwards and building up a stratus layer that later burned off. A few thousand feet higher were rotor clouds that were rapidly moving east with obviously significant wind-shear between the two layers.

These conditions are very frequent at Boulder so it’s important to try to form a mental picture of what was going on. The following is a simplified illustration of how I see it. (This could be wrong but it pretty much matches my still limited experience.)

In Boulder there is a frequent easterly flow at the surface. (After all, we typically launch to the east). The depth of this flow varies between just a few hundred feet and a few thousand feet. As thermals kick off over the foothills by mid-morning, this flow can further intensify during the day as air is pulled in from the plains to the foothills to replace the air that rises up. At altitude, west of the Continental Divide, there is a prevailing westerly flow streaming over the mountains. The air coming across the mountains is pushed down in the lee. At some point the westerly air flow and the easterly air flow have to meet, i.e. they converge. This means that there is basically a surplus of air that has to go somewhere. Since it can’t go into the ground, it must go up. (Note that this effect can even be enhanced by strong thermals breaking away in the convergence zone: where the easterly and the westerly flow meet on the ground and the air is pushed up, the surface winds are usually only mild. That means, the sun has a lot of opportunity to heat the ground because the warm air doesn’t get blown away.) The geographic location of the convergence line varies based on the strength and depth of the easterly and westerly flows. Most often the line is somewhere between the lower foothills and a few miles west of the Peak-to-Peak Highway but there are instances when it can be out in the plains east of Boulder, and there are instances when it can be even to the west of the Continental Divide. (There are of course also days when there is no convergence at all.)

The trick to high XC-speeds is to find the place where the easterly and the westerly flow converge, i.e. the air is pushed up, and then to follow this line as you fly north or south, usually somewhat parallel to the mountains.

Fast XC speeds aren’t the only reason to look for the convergence line. The air on the west side of the convergence is almost always dryer and clearer (less hazy). This means the ground can heat better, the thermals will be stronger, they will develop earlier, and they will reach higher. Soaring on the west side is almost always better than soaring on the east side, especially in the morning when there is often a ground inversion in the valley that has to burn off before thermals can develop at all.

The differences in air quality to either side of the convergence also mean that clouds will look different. Most notable is the difference in cloud bases – they tend to be noticeably higher on the west side. So if you see a step in the cloud base, always try to stay underneath the higher base to the west. You may also see scraggly looking curtain clouds along the convergence line. Stay just to the west of these clouds and you should be in the area of good lift.

Back to yesterday’s flight. I knew there was a strong convergence line but I didn’t get into it. Why?

To find the answer I closely compared the early stage of CX’s flight path and of my own flight path to find out where CX was able to connect with the line, and why I missed it. CX’s flight trace is shown in light blue, and my flight trace, SG, is shown in red.

The following screenshots from SeeYou tell and illustrate the story.

CX turned the engine off right on the inside of the 15km OLC ring, above Sugarloaf mountain, at 11,200 MSL.
I released a little further north and just 300 ft lower at 10,900 MSL.
CX immediately pushed west and tried to find lift just north of Barker Reservoir. CX was down to 10,200 MSL and just able to maintain altitude.
I also pushed a little further west before I attempted my first climb. With the same result. I was also able to maintain altitude but unable to climb. At this point I was at 10,400 MSL.
CX pushed further west and finds lift next to the Peak to Peak Highway. The first few turns are rough with a mix of strong lift and strong sink, but then the climb rate improves. Good lift after 3 turns and now back at 10,300 MSL.
Instead of pushing another 1-2 miles further west while I still had just enough altitude to do it, I hesitated and went for the west side of a small rotor cloud to the south. This rotor did not work and this one decision probably cost me the connection with the convergence.
After another 2 turns, CX has made it. Although he’s still only at 11,500 MSL, he is already confident that he can commence a straight flight along the line.
I am only 2 miles NE of where CX found the connection with the convergence. But the air is rough with lots of gusts and no climb. I am down to 9,800 MSL and do not feel confident that I can push further west without additional safety margin.
CX has clearly made it and is rapidly climbing in straight flight north, already up at 13,500 MSL.
I am desperately trying to claw back a few hundred feet to make an attempt at getting further west. I’m back at 10,100 MSL but also 1 mile further east, and don’t consider my altitude sufficient.
CX has climbed away in straight flight to 16,900 MSL and is now ready for a speed run at altitude.
I’m working hard to maintain altitude but continue to shift east. The further east I get, the more altitude I need for a push westwards.
Eventually I give up on the idea of connecting with the convergence line and aim for the Flatirons instead. After a patch of sink, I’m down to 9,300 MSL and it’s definitely game over for getting back west.
The easterly flow is moving up along the slope of the flatirons. It’s pretty weak at about 6-8 kts but just sufficient to maintain altitude at ridge top level and say hi to the hikers on top of Bear Peak.

After this I continued my flight for a while thermaling over the lower foothills west of the Boulder airport. The thermals were wind-blown and inconsistent and didn’t reach higher than about 8,700 MSL where they were stopped by the wind shear layer between the lower easterly flow and the rapidly moving westerly wind aloft.

So what did I do wrong?

1- I underestimated from the outset how hard it would be to reach the convergence.  In particular I did not appreciate that the strong westerly winds aloft would cap the thermal height such that I would not be able to gain the necessary altitude to head west.

2- Because of #1 I also did not have a clear plan for where to tow or how high.  On tow I was flying in considerable sink as we approached the 15km ring.  Had I released inside the ring, I would have released in strong sink.  So I stayed on beyond the sink and released at the first sign of weak lift.   That was a mistake because I was just a little too low to comfortably head straight west to get to the convergence.  Had I continued on to about 12,000 feet, it would have most likely been sufficient.

3 – I might have had one chance to get far enough west.  This was after my first climb off tow when I made it to 10,600 MSL 1 and one mile east of Gold Lake.  Had I tried to push another mile west from there it might have just worked and I would have had just enough altitude to do it.  Instead, I flew south from there, and at that point my chances to connect without taking undue risks were probably already over. 

Here are links to my flight track and to CX’s flight track.

Lessons Learned

  • A very strong westerly wind aloft and the associated wind-shear is likely to cap the height of the thermals east of the convergence.  The low thermal tops can make it impossible to get the necessary altitude to fly far enough west to reach the convergence (depending on the position of the line).
  • In conditions like these it is necessary to tow high enough to have the necessary altitude to fly west and connect with the convergence before running out of safety margin and having to turn back east.  (Per launch you might have only one chance to get the line and very little time to connect (perhaps even less than a minute).  Seize it when you see it.  A few hundred feet of altitude can make all the difference.)
  • On OLC Speed League days in these type of conditions (when you can’t get high enough in thermals to penetrate west) there are two alternative strategies to connect with the convergence line and get a valid OLC start: 1) tow to about 12,000-13,000 just at the edge (but inside) of the 15km ring, release, and then head west; or 2) tow further west until you’re confident that you can reach the convergence, connect and gain enough altitude to come back out and dip into the 15km ring, and head back west (and connect again).  It is important to consider these alternatives before takeoff and communicate with the tow pilot accordingly.

Post Scriptum

I received several comments via email about this post.  Thanks to everyone who read it and took the time to reply.  Most comments were about SG’s lack of an engine compared to CX.  Here are a few excerpts about what commentators said.

“Big difference you don’t have an engine!”

 “Never compare or try to fly with a motor glider!”

“Sometimes it is better to be safe and soar again another day. (The Discus doesn’t have a motor if you get in trouble.) I wonder how that affects personal minimums?”

“If there was sink all the way to just east of Gold Lake I think I would have difficulty deciding to push much toward the divide when off tow.  I guess after  thinking about it from the back seat, in sink conditions I think I ‘d want to get into some substantial lift before getting off back there.”

Again, thank you for your comments!   Here’s what I would say in response:

  • In my opinion, the engine factor should not make a difference in a pilot’s judgement (after all you cannot rely on the engine starting when you need it and there are many examples when it doesn’t) but (the limited) empirical evidence suggest that it does influence a pilot’s behavior:  a study of all gliding accidents in France over a period of three years showed that the fatality rate in motor glider accidents was almost 3 times higher than the fatality rate in pure glider accidents.  The data set is small but it would suggest that pilots of motor gliders are more likely to take higher risks (e.g. fly low over unlandable terrain) assuming that the engine can bail them out if necessary.  But when the engine does not start when really needed, an accident is often inevitable and more likely fatal.   (BTW – if this is true, it is a classic examples of risk compensation theory – i.e. individuals tend to assume riskier behavior if you add a safety device;  frequently cited examples are that motorists drive faster when driving a car with anti-lock brakes; bicyclists cycle faster when wearing a helmet; and skydivers take more risks as their equipment gets safer.)
  • I do not think that I should have pushed further west to connect from the altitude that I was at.  I think I had an adequate safety margin where I was but my instincts told me not to push any further west and I firmly believe I made the right decision.  I do not want to encourage myself or anyone else to take on undue risks.
  • I cannot speak for CX but here are a few considerations:  In addition to having an engine, CX is a higher performance glider with flaps that enable higher speed penetration through sink, and, most important, the pilot is a lot more experienced than I am.  In addition, CX found lift right next to Caribou Ranch, one of the few landable fields in the foothills.  (For me it’s just an emergency field, i.e. I would never rely on it, but a much more experienced pilot will probably have no problem landing there.)
  • In hindsight, my main mistake on the flight was releasing too early and at the first sign of lift which turned out to be too inconsistent and narrow to climb in.  While this decision did not put me in any danger whatsoever (I believe I always had plenty of altitude to come back safely), it ultimately did prevent me from pushing far enough west to reach the convergence line. 
  • For the avoidance of doubt, I do not at all regret that I did not push further west with the altitude that was available to me.  And I most certainly do not want to encourage anyone (myself or others) to take more risk!

Long (and somewhat exciting) Final Glide

Recently I did a lot of work to update my Boulder 250 sm way point files, including the creation of this Boulder 250 Soaring Map with Final Glide calculations for typical second generation glass ships that would work for our club’s Discus and DG 505.

Screenshot of a portion of the Boulder 250 Soaring Map. The map is interactive. You can show/hide the various different features such as airports, land-out fields, waypoint, 14ers, transitions, unlandable terrain, typical summer soaring conditions, and Final Glide altitudes required for Boulder. Instructions for use and a link to the map are here.

This past Saturday, I had a chance to test my final glide assumptions in real life.

It was a fun but challenging day for flying.  A lenticular cloud shielded much of the area east of the Continental Divide from the sun all morning, causing the day to develop quite late, despite the unseasonally high surface temperatures.   A cold front was forecast for the following day.  In Colorado, pre-frontal weather is almost always associated with an unstable air mass and a risk of over-development once the sun starts to heat the ground.  I expected that the combination of late sunshine and early OD would likely make for a relatively narrow soaring window.  Skysight had projected this to be between approx. 1 PM and 4 PM (which turned out to be largely correct).

I launched at 1:20 PM after the first cumulus clouds appeared over the hills  behind the Flatirons.   For a long time the air was still on tow – the valley was still inverted.  I towed right to the edge of the 15 km ring around Boulder and released in the first weak lift over Sugarloaf.  (I later found out that I had released just a tiny bit too late to qualify for an OLC Speed League start so I should have “dipped back” into the 15km ring.) That lift disappeared quickly and so I headed further west to the nearest cloud, which was above the town of Nederland.  I scratched around for almost half an hour until I found the first decent climb above the windward side of Niwot Ridge (the wind in this area blew at 10kt from the SE – ideal for the ridge).

There I climbed to 16,500 and was able to connect with a convergence-induced cloud street heading NNE.  Finally I could switch to cruise mode.  The street took me more than 40 miles in straight flight past Lookout Mountain NE of Estes Park.   A wildfire north of the hamlet of Rustic generated a lot of smoke drifting east.

Wildfire with billowing smoke next to the hamlet of Rustic in Poudre Canyon 25 miles WNW of Fort Collins. The sky is already over-developed and rain is falling at the Wyoming border in the distance.  (I took this photo on my second approach to this area.  When I tried to pass the fire earlier, the convergence line ran right through the smoke and I could not find lift west of the fire.)

Unfortunately, the convergence line went right through the smoke.  I did not want to fly into poor visibility and sought to make my way around the fire on the west side.  The thermals in this area where weak and wind-blown with significant sink in the lee of Crown Point, one of the mountains along that stretch of the Continental Divide.

When I could not find a comfortable way to get past the fire without losing too much altitude, I reversed course and followed a cloud street back toward the Twin Sisters (S of Estes Park).  The sky to the south was now fully overdeveloped and virga curtains ahead stopped my progress.  I turned back again towards Poudre where the fire kept burning.

I made it all the way to Rustic on this second attempt, and was now finally able to get past the fire without risk of getting engulfed by smoke.  However, the sky was now fully overcast in all directions with many virga to the south and some virga and rain further north.  I wasn’t sure how long there would still be lift and so I prudently decided to head back to Boulder, 54 miles away.

Close-up of the fire. The hamlet of Rustic is at the bottom of the canyon, just above the winglet.  My flight computer did not show any other aircraft in the area and I figured that had a TFR been called, I would certainly be well above it.

I was at 17,000 ft MSL above Rustic.  From my work on the Boulder Soaring Map I knew that this was just the altitude I would need to get to Boulder airport and arrive there at 1,500 ft AGL, flying the Discus (without ballast) at 80 kts in still air (a glide ratio of 1:27).   My flight computer, which was set to MC 3, suggested that I would arrive at 3,000 ft AGL, flying at around 70-75 kts.

Discus Polar. The optimum speed to fly with a 3kt McCready setting is approx. 70-75kts.

There was a westerly cross wind of about 10 kts, which would negatively impact the glide performance, so I figured that 80 kts would be too fast.  I decided to fly just at a little over 70 kts, and see what would happen.   There were several airport landing options along the way (you can also see them on the map below at the eastern edge.)

Excerpt from the Colorado Soaring Map showing purple Final Glide Rings around Boulder. You can see Rustic on the top left next to the number “17”, indicating that 17,000 ft MSL is required to commence a final glide, flying a Discus @ 80 kts dry in calm conditions and arrive at Boulder 1,500 ft AGL.

Things were going very well for the first 25 miles of the final glide.  Instead of flying the most direct line I picked a path further east that connected several distinct clouds within the overcast layer.  Pulling up a little into the wind whenever I crossed an area of lift I kept gaining several hundred feet on my arrival altitude even though my path represented a slight detour.  When I crossed CO Rt 34 east of Drake, my flight computer predicted a very comfortable arrival at Boulder at 3,500 ft AGL.

Final Glide Part 1: from Rustic to past CO Rt 34: Distance 41.37km, altitude lost 1,082m, effective glide ratio 1:38 at average ground sped of 140 kph = 76 kts

But just as I started to be very happy with my performance and secure in my final glide altitude (I later calculated that my effective glide ratio on this first part of the final glide was a remarkable 1:38 flown at an average ground speed of 76 kts), I hit two patches of sink in quick succession.  The first one was relatively mild and lasted less than one minute.  The second one came two minutes later as I was flying past Carter Lake, and was quite severe.  The vario hit negative 10kts.  I pushed the stick forward and accelerated to 100kts to get out of the predicament as soon as possible. Within 1 minute and 16 seconds I lost 396 meters (1,300 feet).

Two sink patches cost me 1,900 feet of altitude and approx. 1,500 feet against my normal projected glide path of 1:27.

When the sink subsided and I had the airspeed dialed back, my flight computer showed a predicted arrival altitude of only 2,000 ft AGL.  Wow!  I had just lost 1,500 ft against my arrival altitude within about two minutes and my safety margin was getting thin.

I tried to make out what had caused the sink but no obvious explanation came to mind.  I was well clear of any virga lines, I had carefully avoided the lee of Blue Mountain (west of Carter Lake)  and the sky looked almost homogeneously gray.  For the first time I felt no longer 100% certain about arriving in Boulder at a safe altitude.  I took a good look at Longmont airport to my left,  which was definitely within easy glide range at this point.

I continued ahead and resolved that I would fly past Lyons and decide then whether or not to divert to Longmont.  Fortunately the next stretch of air was better with minimal sink and some small patches of weak lift.  I passed Lyons at 9,500 MSL and shortly thereafter my predicted arrival altitude in Boulder had climbed back up to 2,200 AGL.

Part 2 of my Final Glide between Carter Lake and Lyons. I covered 15km with a loss of 600m in altitude at an effective glide ratio of 1:25.  My average ground speed on this stretch was 123kph, i.e. 66 kts:  I was now trying to fly as close as possible to best glide speed to preserve every bit of altitude possible.

Just after I had decided that I had an adequate safety margin to continue on to Boulder, I hit another patch of sink near Altona with only 7 miles left to go.  It wan’t as bad as the prior one, but another 600 feet of altitude were gone and my flight computer showed an arrival at 1,600 AGL.

Sink Patch #3 near Altona. Another 600ft of altitude gone. After this patch, my safety margin had been reduced to 600 ft above pattern altitude with another 7 miles to go.

Turning back to Longmont was no longer a sensible option for Longmont was now equidistant to Boulder and my way back would lead me through the same sink I had just crossed.  I made some additional contingency plans:  if I would find lift I would stop to re-gain a few hundred feet.  If I were to lose another 800 ft against my flight path, I would enter the pattern from the north instead of the usual entry mid-field from the south.   In the worst case, I would land in a field west of Boulder Reservoir.  This final glide was definitely more exciting than I had expected!

Fortunately, the remaining part of the glide was uneventful without unexpected sink or lift and I did in fact arrive at 1,600 ft AGL; i.e. with plenty of altitude and time to examine the wind socks and traffic, and to fly a normal high pattern to glider Runway 26.

Final Glide from Rustic to Boulder.

Overall, the final glide was 54 miles long (this includes a 5 mile deviation from the straight course), flown in  35.5 minutes at an average ground speed of 79 kts and with an effective glide ratio of 1:28.   (Calculated over the most direct route the glide ratio was 1:26).  The three patches of sink made the last 10 miles quite a bit more exciting than I had expected even though I ultimately arrived at a safe height of 1,600 AGL.

The flight track is here.

Lessons Learned

  • The glide performance of the Discus seems to be right in line with the glide polar and the final glide rings on the Boulder Soaring Map work.  But: the caveat that glide calculations only work if if the air is still is definitely true.  It’s also good to remember that we only like to go soaring when the air is not still!
  • Even on final glide it is critical to continue to examine the clouds and the terrain and to somewhat deviate from the straight line if appropriate.  This way I achieved a glide ratio of 1:38 on the first half of my final glide.  This allowed me to build up a significant safety margin which ultimately turned out to be necessary to counter the patches of sink during the second half of the glide.
  • A patch of heavy sink can very quickly eat away a significant safety margin.  The glide path looks very different after losing 1,500 feet in two minutes.
  • Having acceptable landing options available as a contingency is absolutely critical on final glide.  Knowing that Longmont was always easily accessible made me perfectly comfortable until I hit the second patch of sink near Altona, when suddenly Longmont was no longer an option.  On any final glide the ultimate stretch after passing the last good land-out option will always be the most critical one.
  • If I’m not racing, I’ll revert back to planning to arrive higher and go past the airport before coming back to the pattern.  The extra excitement in the last few minutes is not necessary.  🙂
  • On OLC speed league days I need to pay closer attention to my release point on tow and dip back into the 15km ring if necessary to ensure my flight counts. (It ultimately did not matter this past Saturday because three other club members had qualifying flights with a better performance.)

Why Practice With Condor?

Soaring is a complex sport. Many different skills are required to become proficient. Every instructor will tell you that the best way to develop these skills is to fly a lot. Unquestionably this is true.

Unfortunately, flying a lot isn’t always easy, especially for beginners.  Unlike experienced pilots, who are able to soar on almost any day of the thermal season, inexperienced pilots often need near-perfect conditions to fly, stay up, and practice.  If the conditions aren’t great (e.g. the thermals are relatively weak, wind-blown, narrow, inconsistent, further away from the airfield, etc.), their flights are often short, and thus their soaring practice remains limited.  This can be frustrating, and, considering the number of tows involved, it is also expensive.

Unfortunately, many new soaring pilots give up at this stage. In fact, the statistics from my club, the Soaring Society of Boulder, show that new members who fly less than five hours in their first year have a more than 50% likelihood of quitting their new hobby before their second season even starts. That’s a real shame if you think of all the time and money that they have already put into their basic training.  But also consider this: those who fly more than 5 hours in their first year have an 80% probability of continuing with the sport!  So what can new pilots do to cross the five hour hurdle?

Fortunately, there is a simple, effective, and inexpensive way to supplement the basic flight training and quickly develop many of the key skills that are needed as a soaring pilot. It is called Condor, a remarkably realistic simulator for soaring flight. If you already have a PC with a decent graphics card, all you need is the software, a suitable joystick, and preferably rudder pedals, and you are set. All of that can be had for the cost of a few tows – see details at the bottom of this post. I promise it is the best investment any aspiring soaring pilot can make!

To avoid any misconception: Condor alone is not a substitute for real-life flight training. But I have absolutely no doubt, that it has saved me dozens of real tows and dramatically accelerated my learning curve as a soaring pilot.  

Below are some examples of how Condor can help you quickly develop your skills .  These skills will allow you to become more proficient more quickly, you will be less dependent on perfect days, and you will have the opportunity to gain more real glider time and experience sooner, and at lower costs.

Foundational Skills

1) Thermalling – The thermals in Condor are exceptionally realistic.  Condor will teach you where to find the best lift, how to center the lift, and how to fly consistent circles with constant airspeed and a constant bank angle.  These skills translate perfectly to the real world.  I am completely confident that anyone who can center thermals in Condor can do the same in real life.  Of all the foundational skills (beyond taking off and landing safely), this one is by far the most crucial if you want to be able to stay up and go places. Condor also lets you set the average width of thermals, the level of turbulence, and the upper level wind speed so you can practice thermalling in more difficult conditions as you get better at it.

Thermalling with another glider during a multiplayer online race in the Alps.  I’m flying a Diana 2 (note the side stick).  The Condor flight computer shows the thermalling assistant and the average climb rate during the last turn.

2) Ridge Soaring – Many soaring sites don’t have good ridges for soaring flight.  Condor allows you to practice ridge running in various wind conditions and experience the effect of lee side turbulence and sink without putting your life at risk.  Your first ridge flights in real life should always be with an instructor but it will be instantly familiar to you once you master it in Condor.

Running along the ridge of Mount Nebo near the airport of Nephi in Utah in 15kt westerly winds. The glider is a JS1.

3) Wave Soaring – Since the recent release of version 2, Condor also does a good job at modelling wave lift although it is not as realistic yet as thermal and ridge flying.  (Especially rotor turbulence below the wave bars is not modeled well, and the interaction between thermals and wave is also not very realistic. ) However, mastering wave flying in Condor will still be of help when you first experience it in real life; e.g. the geographic relationship of the wave trigger and the position of the wave lift is well done and you will have learned the necessary flying techniques to stay in wave lift.

Climbing above 18,000 feet (5,489 m) in wave lift next to a thin lenticular cloud. The flight is in Slovenia, which is the default scenery in the Condor software package (the company that makes Condor is based there). The glider is a Duo Discus, which also comes standard.  (Note that the position of the clouds below the wave seems random like on a typical thermal day.  In reality you would expect lines of rotor clouds instead, roughly parallel to the wave bars.)

4) Take-Offs and Landings – these skills are actually harder to master in Condor than in real life.  If you can follow the tow plane and box the wake in Condor you will likely have little trouble doing the same in a real glider.  Landing in Condor is also a bit more tricky.  A key benefit of Condor is that you can practice things that you wouldn’t do in real life such as taking off and landing in extreme conditions.  One day you may find yourself in a situation where you have no choice but to put your glider down in a 25 kt crosswind or quartering tailwind.  It’s definitely helpful having practiced this on the simulator.  You can also do these maneuvers over and over again without incurring any additional cost.

Aerotow takeoff in Nephi in an ASK 21 behind a Super Cub with 27 kts cross-wind. You can see the glider drift immediately to the right of the center line despite the crab angle. The maximum demonstrated cross-wind component for the ASK 21 is 8 kts. So you definitely would not do this in real life. But it’s fun to practice it in Condor.

Advanced Skills

One great thing about Condor is that it was originally developed for glider racing.  That means, the learning doesn’t stop with the basics.  In fact, there are a lot of advanced skills that you can readily practice in Condor that are difficult to practice in real life.

1) Using a Flight Computer.   As you progress and get interested in cross country soaring, you will want to become proficient in the use of a flight computer.  Condor has one built-in, which is easy to use, and a great tool for online racing helping you with navigation around the task, speed-to-fly calculations, and final glide.  But, even more important, Condor gives you the opportunity to directly connect your real life flight computer with Condor (e.g. an Oudie).  This way you can practice flying particular tasks using your own real-life flight computer.  I have found this to be a huge benefit.  Flight computers tend to be pretty complex and the last thing you want to do is stare at a screen when you sit in the cockpit of a real glider, trying to understand what it’s telling you, while you really ought to pay attention to what’s going on outside the cockpit.  Not only will you not be able to use the flight computer to your benefit, you are also a safety hazard to yourself and anyone around.  Practicing this in Condor is a great way of becoming proficient without the risks.

Condor has an easy-to-use built-in flight computer which is optimized for FAI racing tasks.  The picture doesn’t show Condor’s flight computer but my personal real-life Oudie flight computer connected to Condor and setup for a Turn Area Task (aka Assigned Area Task) in the Nephi scenery. Turn Area Tasks are not yet supported by Condor – I think this is planned for a future update. My task on the Oudie is based on the 3rd day at the Nephi Sports Class Nationals in 2018. Minimum time is 4:00 hours. The plane is heading towards the start cylinder. I’ve sampled some thermals and set MC to 8 kts because the day seems very strong. Most of the navigation boxes are not displaying useful information until I leave the start cylinder and get underway.  (If you are interested in using an Oudie for Turn Area Tasks, there is a great tutorial here.)

2) Terrain Transitions. Condor was built to fly cross country.  One of the trickiest aspects of XC flying are terrain transitions, especially upwind in mountainous regions.  You’ll learn how much extra height you need to cross a mountain pass when flying into the wind, and you’ll figure out where and how to best gain that height.

Approaching a tricky terrain transition across the pass straight ahead. The wind is from the southwest and the vario shows a modest climb rate of 1 m/s (2 kts). I’m counting on additional ridge lift from the slopes to the left before sliding over the pass and into the next valley beyond. There is likely some sink in the lee of the steep mountain to the right of the canopy before getting to the ridge that I have to cross and I need to gain some more altitude quickly. I probably have another 10-15 seconds or so to decide whether I can make it or if I should turn away to the right, come back to the ridge, and try to climb higher before shooting over the pass. This is definitely a very tricky situation of the variety “do not attempt this in real life”. But it is very educational in learning to judge the relationship between terrain and wind, and the glider’s energy in form of height and airspeed.

3) New Terrain.  Condor has a very committed user community.  Several talented members put in many hours  developing photo-realistic sceneries for many of the world’s best soaring areas.  Many of these can be downloaded for free (consider a small donation to the creator) at the Condor Club fan site.  E.g., you can fly in the Alps, in New Zealand, the Andes, the Atlas, the Pyrenees, etc.  I have recently practiced in the excellent Nephi scenery in preparation for a real life soaring camp in Nephi, UT this summer.  Being familiar with the terrain is obviously hugely beneficial before you fly at a new location.

This is an image of the Dachstein mountain near the airfield of Niederoeblarn in Austria where I first learned to fly gliders. It’s taken from a similar perspective as the cover picture on my blog In Condor I am flying an LS8neo whereas in the real image the glider is an LS4b.

4) Flying in Different Gliders, with and without ballast.  Condor is realistically simulating many different gliders from frequently used school gliders (e.g. ASK 21) to the latest and most expensive racing machines (e.g. Ventus 3, JS1, ASG 29, Antares, etc.)  The Schweitzer 1-26 is also supported as well as several other historic gliders.   A number of gliders comes standard with the software package, others are available for an extra fee.   You can experience the different handling characteristics of different ships with and without water ballast, and with different CG positions.  Obviously you can also practice flying with flaps if you select a flapped ship.

Outside of Condor it is unlikely that you will get the chance to fly an open-cockpit Grunau Baby in ridge lift along steep Norwegian Fjords. It’s fun to try out the completely different flight characteristics of different gliders.

5) Glider Racing.  Perhaps the coolest thing about Condor is live multi-player racing  against the world’s best Condor racing pilots.  Many of them are experienced racing pilots in real life and you can test your skills in live competitions.  After a flight you can compare your flight trace against the traces of those that were faster and see where you lost precious minutes on task.  You also experience flying in big gaggles – there are many races with 30, 40, 50 or even more other gliders, all of which you can see live on your the screen.  Most scoring is based on the 1000 pt format used for real glider races, and some races are scored based on the Grand Prix format with regatta starts.  Races can be high adrenaline events and a lot of fun.

Here I’m on the grid waiting to be aerotowed during a multiplayer online race. You can display/hide a directory of the other competitors with a key stroke. This was one of the first online races following the release of Condor 2 and the Diana 2 was the only 15m class glider supported at that time. In the meantime you can also fly a Ventus 3 in 15m configuration.

Limitations of Condor

As I tried to point out, Condor is a fantastic tool to help anyone (from beginner to advanced pilot) hone their skills and become better at real soaring.   It is remarkably realistic and almost all the skills learned with  Condor translate directly into the real world.  That said, it is of course a simulator, and as such it has certain limitations that are useful to contemplate and understand.

1) There are no g-forces.  Obviously.  You are sitting in your chair in front of the computer and you can’t feel lift and sink. So you have to hone these skills in real life.  There is no substitute.

2) Condor does a great job at modelling thermals, ridge lift, and – to a somewhat lesser degree – wave lift.  However, it does not model some other real-life weather phenomena such as weather fronts, convergence lines, or sea-breeze fronts.  This is an obvious limitation, especially when using Condor as a training tool for new soaring areas, where some of these phenomena are typical.

3) There are no weather hazards.  With Condor you are in control of the weather settings and can select (before each flight), how strong the wind will blow (and with what variability), how strong the thermals will be, where the inversion layer is (and therefore the cloud base; or if the day is blue), if there is is wave and how strong, etc.   But there are no thunderstorms, squall lines, tornados, or hurricanes. There’s also no precipitation, i.e., no snow, hail, or even rain. Condor weather is always soaring weather.  The greatest wind strength at the surface is 50 kph (just under 27 kts).   (Higher up in wave, it can be twice that.)  Hazardous weather is obviously something you need to really think about and plan for in real life.  Condor won’t teach you that aspect of soaring.

4) There are no airspace restrictions and you don’t learn radio etiquette.   Condor gives you the opportunity to set up penalty zones and thereby simulate airspace but in general, you can fly anywhere and there are no TFRs.  You can chat with other pilots online but you won’t learn proper radio communications.

5) Some of the controls are obviously different from a real glider unless you build your own cockpit with authentic input devices for flap handle, spoiler handle, gear retraction handle, break handle, release knob, etc.  (Some clubs have actually done that but it really isn’t necessary.) You will want to use a mix of keys on your keyboard and joystick buttons for those functions.  I urge everyone to at least use a good joystick and rudder pedals even though Condor will work without them.  But if you want to use it as a training tool for real gliders, you need to operate the main flight controls in a realistic way so you develop the muscle memory to react appropriately.

6) Your life is not at risk.  This is not just a big advantage but it is also a limitation.  There is no doubt that you are likely to take more risks in Condor than you should ever take in real life (a case in point is the screenshot of the mountain pass earlier in this post).  You can also see this in online racing:  almost at every multiplayer race, one or more of the competitors end their flights in a crash (which in many cases would be fatal in real life).  Condor is very tempting in this regard: to gain precious seconds you might scratch over mountain passes with a few feet to spare; you might fly between clouds in close proximity to mountains, you might fly in extremely dense gaggles, etc.   I remind myself each time when I assume a risk in Condor that I would not be willing to take in real life.  The last thing I want to do is teach myself hazardous habits.

These limitations are real.  You should understand them but they should in no way deter you from using Condor not just as a game, but as a tool to practice various flying techniques in preparation for real soaring.

What do you need to fly in Condor?

At the minimum you need the software and a computer that can run it.  You find the system requirements here.

In my experience an excellent set up looks like this:

  • A computer with a good-sized screen and a fast graphics card that supports Condor in high resolution.  You can get all the training effects on a smaller screen, and with a barely adequate graphics card, but the experience is obviously much better if you have a nice computer.   Condor requires Windows but it can also run on a Mac booted up as a Windows machine.  E.g., I run Condor on an Apple iMac running Windows through Bootcamp.   There are some geeks that run Condor with multiple computer screens.  (If you want to fly in different sceneries (landscapes), you will also want an external hard drive because photo-realistic sceneries take up a lot of storage space – some are larger than 50 GB and you may want 10 or 20 different ones.  You can either install Condor and all the sceneries directly on the external drive (the easiest solution) or you can install Condor on your main harddrive and use the mklink /J command to link to sceneries that are on your external drive.  If you don’t know how to do this, ask me when you get there.  It’s easier than it sounds.) 
  • A joystick with force feedback. The best one is most likely the Microsoft Sidewinder Force Feedback 2.  For a long time I used a a Saitek AV8R joystick without force feedback but after reading the glowing recommendations from the Condor user community for the MS Sidewinder, I switched and I can attest that the experience is incomparable and hugely improved.  The MS Sidewinder acts and feels just like a real glider stick.  The forces depend on airspeed and attitude, and the stick will even indicate the buffeting in a stall just like a real glider.  The MS Sidewinder has been long out of production but you should be able to get a used one on eBay.  They are very sturdy and well built.  I highly recommend it.  Whatever joystick you use, Condor allows you to easily program any of the buttons and levers to your desired functions.
  • Rudder pedals.  There are multiple ones available and probably any of them will work well.  I use T-Rudder MKIV pedals from KBSim, which are heavy and sturdy and work very well.  But less expensive ones will definitely do as well. 
  • A head tracking device such as the TrackIR 5, which is what I use myself.  This is not essential but it does make a very big difference.  It basically allows you to move your head to control what you see on the screen.  If you want to look out over the left wingtip, you simply turn your head a little to the left as you would in real life and the screen will move just as you move your head.  If you don’t have a head tracker you can alter the view by moving your mouse with one hand while you fly the ship with the other hand, or you can use the head-switch on the joystick.  But neither is easy to do, especially if you also want to change flap settings or control the spoilers at the same time.  Using a head tracker is much easier and more intuitive.  For online racing, using a head tracker is almost essential unless you don’t mind colliding with other gliders in dense gaggles or along ridge lines.  (There’s one thing to be aware of when using a head tracker:  it will not work if there is sunlight coming in from behind where you are sitting when you look at your computer.  The sun will confuse the tracker and the screen will jump all over the place.  So think about where you will use Condor before you decide to buy this item.  (Most recently, Condor now also supports virtual reality devices such as Oculus Rift, which would make a head tracker unnecessary, but I have not tried this feature yet.)
  • Condor has a built-in flight computer that is easy to use and specifically designed for Condor.   It will help you with navigation, thermal centering and teach you all you need to know about MC speed-to-fly, final glide, arrival altitude, etc.  If you also have a real-life flight computer that you want to practice with using Condor, check if it can receive GPS data through a COM interface. Most should be able to do it.  Note, however, that the Oudie IGC does not allow this because it only accepts GPS data from it’s own built-in GPS.  The Oudie 2 and Oudie 1 will work just fine.  If you have an Oudie 1 or 2 you will also need a dedicated cable to connect the Oudie with your computer.  I have no experience using other flight computers with Condor but you typically can find what you need on the Condor user forum.  
  • Finally, you will want to use earphones with Condor, unless you live alone.  Any ear phones will do as long as only you can hear them.  I promise that a beeping vario from your computer would annoy everyone around you in no time.

You may already have several of the things needed.  But even if the only thing you have is a computer,  you can get all you need for about $100-400. Cumulus Soaring even sells the essential components in various bundles priced between $117 and $380 if you don’t want to follow my hardware recommendations or go to the trouble of making your own choices.  The price tag may sound high, but, as I mentioned earlier, you should look at this as an investment.  It will ultimately safe you a lot of money in tow fees and you will become more proficient much faster.

Now, unless you are already an expert and master all the skills listed, go and get Condor.  You won’t regret it.

(Disclosure:  this article reflects my own personal opinion and is not unduly influenced by anyone else.  In particular, I have no relationships with, no financial interest in, and receive no benefits from the sale of Condor, Cumulus Soaring, Amazon, eBay, or any of the recommended hardware or software products. )

P.S.:  if you would like to learn more about how Condor can be formally used as a tool for flight training, I recommend you check out the series of articles by Scott Manley, CFI-G, that have appeared in Soaring magazine monthly since June 2018.  Scott provides flight instruction at a distance year-round using Condor and Skype to glider rating candidates across the United States.   He is also a frequent speaker on this topic at SSA conventions and in other forums. You can contact Scott at or via his website  

Speed Surfing the Rocky Mountain Wave

Yesterday was a glorious day for wave soaring along the Colorado Front Range.  But first I had to get there.  Almost every wave flight in Boulder begins with a climb in the wave’s rotor…  which is always a piece of work and not for anyone who’s just out for a pleasure cruise.

Boulder, CO from the wave at 17,500 ft MSL with rotor clouds below.

As I climbed behind the tow plane – we had barely reached 1,700 AGL ft – all of a sudden, the tow plane shot straight up into the sky.  From my glider cockpit’s perspective it looked like I had instantly dropped down to the low tow position.  But I did’t try to correct it for I knew what was about to happen.  And sure enough:  two seconds later I felt a huge bump from below and my high tow position was restored on it’s own without any control inputs.

A long line of cap clouds tops the Colorado Front Range. The cap cloud is a typical sign of wave conditions. The cap clouds dissolve in the lee of the mountains as the air warms up as it gets pushed down along the lee slopes, opening a “Foehn Gap” to the next line of clouds downwind (not visible here). The small clouds below are rotor clouds.

After a quick look to the right I pulled the release. Two turns later I had already climbed 1,500 feet off tow.  What an elevator ride!  The oxygen system started peeping, confirming my rocket-like ascent.  Why hadn’t I put the cannula on before taking off?  When I reached for it I noticed the extent of my mistake:  when I closed the canopy before taking off, I had trapped the cannula’s tube between the canopy and the fuselage.  There was no way to get it out. Bummer!  You really can’t go on a wave flight without oxygen.  So, just a few minutes into the flight and on a fast track up into the wave I was left with nothing else to do but to put the gear back down and pull the spoilers out.  Three minutes later I was back on the ground.  I grabbed a new cannula, and took another tow…

A close-up shot of the cap cloud. The fuzzy area below the cloud is blowing snow due to the strong surface winds directly above the mountain range. The air flowing over the mountains gets squeezed between the inversion above and the mountains below, thus accelerating the wind speed at the tops of the ridge line. The wind would have made back-country skiing really unpleasant.

I asked the tow pilot to take me to the same spot where I released in anticipation of another rocket climb.  However, this time, climbing off tow wasn’t nearly as easy.  I hit some big sink and dropped down to 2,000 AGL.  Time to pay attention!  This close to the ground, strong lift and strong sink were in very close proximity to one another.  The vario flipped back and forth between max climb and max sink indications, and I had to bank about 50 degrees to get a positive average climb rate.  To make matters more challenging, the position of lift and sink changed constantly.  After some experimenting, I eventually found a reasonable spot to climb in.  The higher I got, the more consistent the lift became and my climb rate improved.

On my first leg north. Below the rotor cloud on the right is Carter Lake.

At about 14,000 MSL I got into weak laminar lift and was able to relax.  I pointed the nose into the wind, noticed that I was barely moving forward relative to the ground.  Occasionally I looked back over my shoulder to watch the developing rotor clouds behind the plane.   More than one glider pilot before me got “swallowed” up by the clouds as their glider drifted backwards.  I knew I had to be careful so this would not happen to me.   Gradually I gained another 3,000 feet and the rotor clouds were finally below me.  The hard part was over and it was finally time to cover some ground!

Another view of the Continental Divide northwest of Carter Lake. The Twin Sisters and Mount Meeker / Longs Peak can be made out right of center underneath the cap clouds. The town of Estes Park is in the distance on the right edge of the picture.

With the wind blowing at about 30-40 kts I knew I had to fly fast if I wanted to get anywhere for a significant portion of my airspeed would be used up just to avoid drifting off with the wind.

Unlike on some of my prior wave flights,  there was no continuous line of rotor clouds.  However, many smaller, individual clouds were sprinkled about the sky below.  There were enough of them and in sufficiently regular intervals to easily work out the area where the best lift was likely to be.

Nice view out into the prairie to the East after my first northerly turn. The suburbs below the rotor clouds belong to the city of Loveland.

And so the surfing could start.  Depending on the strength of lift I would adjust my airspeed.  But unlike flying in thermal lift, where you pull up when the lift increases and you push down when the lift decreases, I would basically do the opposite:  In strong lift I would push and fly faster to avoid getting close to Class A airspace.  In weaker lift, I would pull back a little, to avoid dropping lower and possible getting back into the rotor zone.  The sweet spot was clearly between 16,500 and 17,999 feet.  High enough to stay clear of the rapidly developing rotor clouds and the associated turbulence below, and low enough to avoid busting into forbidden territory.

Downtown Denver on my second leg, heading south.

For the next hour and a half I flew up and down the front range between CO Rt 34 in the North and I-70 in the South.  The strength of the lift varied between 2 and 10 kts.

In exactly 1 hours and 30 minutes I covered 275km, that’s an average ground speed of 183 kph or 114 mph or 99 kts.   I stayed between 16,300 and 17,800 feet for the entire time. Except for reversing directions at the northern and southern turn points I made not a single turn.  My indicated airspeed was  between 80 and 100 kts most of the time, only occasionally dropping a little lower – mainly to open the window and take pictures.

The cap cloud stayed with me for the duration of the entire flight as a constant reminder that the wave continued to work. This picture is from my third leg, heading north again.

I had not remembered the exact VnE of the Discus at this altitude, and so I decided to err on the conservative side, keeping my indicated airspeed below 105 kts at all times.   This meant that on several occasions I had to pull the spoilers to prevent the ship from climbing above 18,000 feet.   (I have since checked the operating handbook and my actual VnE at this altitude would have been 124 kts.)

There was a lot of commercial air traffic in and out of Denver International at my altitude.  It was very comforting to know that the ship is equipped with a transponder and ADSB out so ATC was aware of my position and heading at all times.  The screen of the S100 showed me the other aircraft in the sky, usually well before I could spot them myself.  The color coding was very useful as well, so I could see whether to look for other traffic above or below.

Last picture before putting the camera away and getting ready to descend. The panel shows the typical cruise mode for the flight. Speed around 100 kts, lift 2-3 kts, altitude 17,500 MSL.

Visibility was absolutely perfect for the entire flight and the excellent wave conditions reached to the horizon to the north and the south as far as the eye could see.  I have no doubt that it would have been possible to continue the speed run north to the Wyoming border, and south all the way to Pikes Peak.

Unfortunately I wasn’t very well dressed for this altitude.  Once the sun was blocked by a lenticular cloud layer far above it got really cold very fast.  That’s when I decided to cut the flight short and come back down to land.

Before leaving the laminar layer on the descent I made sure to secure my camera and any other loose objects in the side pockets and I retightened all my belts.  I slowed down to below 80 kts to minimize getting knocked around too badly once I would re-enter the rotor zone, and I kept away from the proximity of rotor clouds where the most severe turbulence is usually found.

I don’t know if it was due to my precautions or if I simply got lucky but ultimately my re-entry into the rotor zone wasn’t nearly as bad as I experienced it before.

AWOS told me the wind on the ground had turned west as well and was blowing at 20 kts gusting to 28.  The wind sock suggested a slight northerly cross wind component.  I landed on Glider 26, making sure the touchdown was before the line of trees that could add some unpleasant turbulence.  The ship rolled nicely all the way to its tie down spot.

The flight track is here.

Lessons Learned

  • Don’t squeeze the cannula!  I need to make it a habit to put the cannula on before launching.  It’s easy to do in flight, but this will prevent me from closing the canopy and squeezing the cannula tube between the canopy and the fuselage.
  • Know the VnE at altitude. Our club’s Discus’s VnE at 18,000 MSL is 124 kts.  I could have flown a bit faster instead of opening the spoilers.  (As long as I’m well clear of any rotor turbulence and there is no rough air).
  • Dress more warmly for wave. Especially the feet and legs get cold in the shade below the glare shield.  And especially when flying fast.


Emerging From the Den

What do Colorado bears have in common with glider pilots?  As soon as the spring sun heats the ground, and the ground heats the air, both come out of their dens.

Except that for many of us glider pilots, our den this year was the hangar.  And we didn’t get to sleep in.  For the past 10 weeks several of us spent a lot of time redoing the panel on our club’s Discus CS under the tireless, thoughtful, and diligent guidance of Jack, our ship manager. Not even a broken leg would deter him…

Here’s what we started with: a new fiberglass panel

First, holes needed to be cut with a water jet to place the new instruments.

Then it had to be fitted into the ship. Clearly, it’s still too wide…

Mounting holes had to be drilled and the the instruments had to be fitted.

Then the real work began … all the invisible parts had to be mounted somewhere before any of the tubes or wires could be connected.

Wires to various sensors and new pneumatic tubing to the ports and probes had to be laid securely below the seat pan

Finally everything had to be mounted, hooked up, and tested. Faulty parts had to be replaced, and everything tested again.   (There’s a lot of steps and pics missing in this sequence before we could call it a success…)

It’s been a major team effort – unfortunately some key team members are not in this picture.

After 10 weeks of work, Jack drove the ship back to the airfield while the sky above beckoned.

Then, yesterday, finally,  I had the honor of test-flying the ship.  And voila, everything worked perfectly.  All the little issues that had plagued the ship from time to time in the past such as erratic vario displays due to leaky tubing, power failures due to old batteries, poor radio reception, an unreadable flarm display, stick thermal indications due to faulty compensation settings, etc… all those issues where gone.

The new S100 flight computer, which isn’t just your task planner and speed-to-fly calculator, but which integrates every available information into a central hub is a thing of functional beauty.  Other air-traffic, even commercial airliners, showed up on the display, color coded by height.  I spotted glider pilots with their call signs on the screen before I could see them for real.  The temperature sensor told me when I climbed to freezing altitudes, the gear warning was a friendly voice and not an obnoxious sound the meaning of which has yet to be deciphered.  The thermal assistant provided timely and accurate information.  The screen is super bright and easy to read at a brief glance even with my polarized sunglasses.  Climb and sink indications agreed with the fully-compensated mechanical vario.  I could just keep my eyes outside the cockpit, focus on the sky, the wind, and the sun and not worry about any of the little things that can become distractions.  That’s soaring as it should be!

As always, the Discus handled perfectly.  The coolest thing is that it basically thermals on autopilot.  Whenever I put it in a 45 degree bank it  just stayed there without further control inputs.  You can even take your hand off the stick, adjust your oxygen cannula, take pictures and just make small corrections with the rudder pedals while the ship basically climbs on its own. You can just look outside and watch the world become smaller and smaller.

I want to thank everyone who’s contributed to this major club project.  We have a fleet of  terrific club ships, which only very few clubs in the United States can offer their members.   Come out to the field and enjoy!

View of the Front Range from the Lower Foothills SE of Estes Park. Soaring was better than the sky suggests.

So here’s a bit about the flight itself:  I got a late launch at about 1:35pm when thermal conditions were almost  at their peak.  As soon as I was satisfied that everything was working and that I wouldn’t need to test the parachute as well ;-), I released at 1,700 AGL and immediately climbed a few thousand feet off tow.  The sky was mostly blue with a few clouds near Thorodin Mountain SW of the Flatirons.  So that’s where I headed first.   But all I could find was sink.  I hadn’t even reached Gross Reservoir when I decided to head back to the prairie.  The thermals were still there but the wind had started to shift to the west. That meant the climbs were less consistent and more wind blown with a somewhat “rotory” feel.

As a climbed, a line of small rotor clouds developed NW of the field to the west of Left Hand Canyon.  I gingerly headed towards that line, pulling a little in every gust and pushing through any sink.  I was able to connect with that line and then fly in cruise mode all the way to the ridge line NE of Estes Park.  This was a good stretch to spot commercial air traffic inbound into DIA on the Flarm screen of the S100.  It was very comforting not solely having to rely on ATC to see me, but to see the airliners myself on the screen before spotting them in the sky.

I found good lift on the ridge near Storm Mountain where I climbed above 14,500.  The sky to the north from there looked pretty bleak, so I decided to retrace my track while another rotor line formed further east.  I connected with that line between Carter Lake and Berthoud, climbed back up to over 14,000 and then imagined a straight line south from there with relatively good air.  Although there were no clouds the line worked in reducing my sink rate and supporting my glide.   I headed past Boulder and the Flatirons towards some rotor clouds north of Golden.  These did not work at all, however.

I turned towards the Flatirons, intent on soaring along the top of the ridge where I expected significant ridge lift since the wind speed had picked up considerably and was now 20-30 kts from the west.   Unfortunately the push through the lee and into the wind cost just a bit too much altitude and I was not comfortable with my height as I got toward the Flatirons.   I remember thinking, “if this were Condor, I would just go for it, and I’m sure it would work”.  But this wasn’t Condor, and in the real world I only have one life to live, so it was an easy decision to turn away.

I pushed through the heavy lee sink at about 100 kts and arrived at the field at a comfortable height of just under 2000 AGL.  The wind was blowing straight from the west at 20 kts gusting to 25.  A sporty pattern flown at about 80 knots brought me to a smooth landing after a flight of 2 hours and 15 minutes.  At 168km it wasn’t particularly long, and at 78 kph it wasn’t particularly fast, but I’m satisfied that it was about what was reasonably possible for me with such a late launch and the onset of strong west wind conditions.

Finally, here’s a look at the new panel in flight as I’m cruising in good lift along the rotor line heading north. The small clouds in the distance (right in front of the nose) were my northerly turnpoint near Storm Mountain.

The new Discus Panel. Everything worked perfectly!

Lessons Learned

  • It’s great to be in a club.  I have learned so much from all the talented fellow club members during this project.  Taking care of a glider felt intimidating to me and for many things I would not have even known where to start.  Compared to my club mates I still know very little but at least I have a basic understanding how everything works and I have a reasonable idea as to what I can do myself and where I still need help.  The whole thing is no longer a total mystery.  And that’s huge progress for me.
  • The flight controls of a glider are mechanical and quite simple; but the entire pneumatic, electric, and electronic systems are another matter.  While only very little of it is needed to fly safely, it does make flying easier and more enjoyable because – when everything works – you can focus on what’s outside the cockpit and not worry about glide calculations or the accuracy of any of the instruments.
  • The flight itself held some new lessons, too.  I experienced the transition from thermal to rotor conditions and the effect this had on the thermals in the prairie.  When I noticed what went on, I adjusted appropriately to the new situation and switched to “rotor flying”.
  • Intent on circling as little as possible, I consciously practiced “feeling the air” as I was cruising along the rotor line.  Whenever I felt some lift I would gently pull up into the rising air, and whenever I felt some sink I would try to gently push away from it with careful and limited control inputs.  It’s hard to know if I did it right – that would have required another glider to my side flying straight at a constant airspeed – but my subjective feeling is that it worked quite well.
  • When approaching the Flatirons with questionable altitude to get above the ridge I am glad I immediately made the right call without hesitation.  I always worry a little that flying on Condor might teach me to take undue risks (I actually always tell myself on Condor that I would not do XYZ in real life whenever I approach a risky transition) and I’m glad the same thought came to me in this real life situation with the very clear opposite outcome that favors safety above everything else.  I’m committed to keeping it that way.

2018 – My Soaring Year in Review

At the beginning of 2018 I was little more than a beginner when it comes to soaring.  Although I had first learned to fly gliders all the way back in 1983, I had not flown at all for 30 years.  I had only recently started all over again when I regained my glider pilot’s license in Austria in June 2017, followed by a US glider certificate in August 2017. By the end of 2017 I had still less than 100 hours as pilot in command.

My goal for 2018 was to pull myself out of the beginner category, develop my skills, and advance to intermediate soaring pilot. Below are some of the highlights of my soaring year.

The first opportunity to learn came early in January when the combination of westerly winds flowing over the Continental Divide and a stable air mass conjured oscillating mountain waves, beautifully marked by long lines of rotor clouds, thanks to just the right level of moisture content. After releasing from tow at just 7,900 feet, I climbed through 17,000 feet 15 minutes later, and was able to practice transitioning between wave bars upwind and downwind. 

January 9 – first fight of the year on a nice wave day

The arrival of Spring promised longer days, more sunshine, and thermals. Ironically, my first thermal flight of the year was under mostly overcast skies.  But the day was characterized by a highly unstable air mass, which, although prone to early over-development, generated thermal updrafts very quickly and easily.  I kept heading for spots where the sun had just penetrated the clouds even if it was just for 10 to 15 minutes, and often this was enough to break another thermal off the ground. Although I couldn’t go very far, the rising air kept me up and interested for about three hours.

March 26 – first thermal day of the year under overcast skies

Spring time is fickle in Colorado and the winter can be difficult to shake off. And so April brought back the opportunity for another late-season wave flight, which turned out to become the flight with the highest average speed for the day on OLC worldwide. I had not even tried to go fast but flying in strong wave lift along a long mountain range basically forces you to maintain a straight course and you have to put the nose down and speed up simply to stay below Class A airspace.  The result was a 325 kilometer flight with an average speed of 152 kph (82kts).

April 4 – The sky was not be screaming “wave” but the lift was strong, inducing me to fly the fastest flight on OLC worldwide for the day.

The Soaring Society of Boulder is one of the most successful clubs in the annual OLC Speed League competition in the United States, and I felt compelled to test my skills on the first Speed League Weekend. It was a challenging day with weak thermal lift over the foothills and a strong inversion over the prairie. A convergence line sat almost on top of the Continental Divide, promising better lift further west but I was unable to reach it. I ended up scratching along in weak lift over the foothills between 500 and 1000 ft AGL, resulting in a 150km flight with an average speed of just 42.6 kph. Not good enough but a worthy attempt.

April 22 – first OLC Speed League weekend in weak thermals over the CO foothills

On May 20, I ventured for the first time beyond gliding range of any airport by flying into South Park and getting within 20 miles of Pike’s Peak.  It’s a strange sensation when you realize that you are truly dependent on the elements and your skills to interpret and use them to your advantage. There were also other great lessons for me in this flight such as speeding along under a cloud street for 30 miles at 220 kph, and really learning to understand the significance of the convergence line that so often characterizes the soaring conditions along the Continental Divide.

May 20 – For the first time beyond gliding range of any airport

Another strong convergence line day allowed me to plan and execute a speed run along the foothills and fly a pre-declared 300 km triangle, thus earning Diamond Goal in 2 hours and 34 minutes.  The flight was also the fastest from Boulder for the day, earning 118 points for the OLC Speed League.

June 25 – Diamond Goal in 2 hrs 34 min. The red line shows the flight track on task, following the convergence line.

One of the greatest soaring challenges for any pilot is to fly above Colorado’s 14ers – mountain peaks that are more than 14,000 feet tall.  There are 53 of them (58 if you also count adjacent peaks), and very few pilots have conquered them all – it’s a quest that can take an entire soaring career and still remain elusive.  In 2018 I started out on my own attempt. My flight on July 19 took me into the Mosquito Range enabling me to tick five 14ers off my list in one single flight bringing my total to eleven. (But that only means that I now have collected the easy ones – it’s going to get much harder from here on out…)

July 19 – Flying over Mt. Sherman and other 14ers in the Mosquito Range

August took us to Europe to visit family and friends. By this time of the year the local peak soaring season is usually coming to an end, and I knew I had to take the first opportunity if I wanted to do some cross-country flying. That chance came  on August 4 when I was able to fly my first pre-declared 300 km triangle in the Alps, taking me along the main spine of the Alps, soaring “from bone to bone”.

Aug 4 – Soaring along the Northern Limestone Range in the Austrian Alps after completing a 300 km triangle

As expected, soaring conditions deteriorated throughout August but that gave me the opportunity to add a self-starter endorsement to my Austrian glider pilot’s license. And, occasionally, I still found the opportunity for a nice soaring flight, even when conditions had become challenging.

Aug 22 – Dodging late summer thunderstorms in the Central European Alps

One of the great attractions of soaring is that the learning never ends. The weather phenomena that enable us to soar are extremely complex and forever changing. Reading the sun, the ground, and the sky and anticipating what will happen in the next 10 minutes, in the next hour, and in the next 3-5 hours is a constant challenge. Deciphering how it will affect the movement of air currents and the location of the best lines of lift is an even greater puzzle.

I have definitely made progress in 2018 but I am also well aware of how little I still know. Which only makes me look forward to the 2019 soaring season.

2018 Milestones:

  • Silver Badge
  • Gold Badge
  • Diamond Goal (3 times: twice in Colorado, once in Austria)
  • First flight over 500km
  • Flown Above 11 Colorado 14ers
  • Self-starter license, Austria
  • Fastest flight on one day on OLC, worldwide

2018 Basic Stats:

  • 59 Glider Flights
  • of which 48 as pilot in command
  • of which 11 as 2nd pilot
  • Total Soaring Time:  101 hours and 54 minutes
  • of which as Pilot in Command: 95 hrs and 48 minutes
  • of which as 2nd Pilot: 6 hrs and 6 minutes

Types of Gliders Flown:

  • Schweitzer SGS 1-34
  • Schleicher ASK 21
  • Schempp-Hirth Discus CS
  • DG Flugzeugbau DG 505
  • Rolladen Schneider LS4b
  • DG Flugzeugbau DG 1001
  • Falke SF 25c


  • KBDU – Boulder, CO, USA
  • LOGO – Niederoeblarn, Austria

Dodging Storms in the Alps

Lift and rain are often found in close proximity to each other. Very pretty scenery north of the Enns Valley.

On August 21/22 I earned my Austrian add-on license to fly self-starting gliders (with the aid of a built-in propeller engine).  This took 14 takeoffs on day one and another 11 takeoffs on day 2 for the required minimum of 10 flights with an instructor and 15 solo flights.  All of these flights were in a Falke SF25c motor glider – with a glide ratio of less than 1:20 not exactly the most efficient machine…

Once in a while it is nice to fly a lot of patterns – you get really proficient at takeoffs and landings. Being able to confidently land a glider again and again on the same spot and at the absolute minimum speed is definitely a useful skill to have.  After completing 11 flights on day 2 in just one hour and a half I had the entire afternoon open to actually go soaring on what looked like perhaps one of the last good thermal days of the season.

Rain seems quicker to fall from cu’s in the Alps (compared to the Western US) – possibly a consequence of a higher moisture content. Also, virga are largely unheard of. If it rains, it rains.

I had no glider reserved and was lucky that the club’s DG 1001 was available.  The air mass looked quite unstable with a substantial risk of overdevelopment so I decided that I wouldn’t venture much beyond glide range of the airport and keep a good eye on the weather.

Once again I released above the trusted Karlspitz.  To my great surprise there was no lift to be had above its ridge lines.  After trying for several minutes I headed under the cloud above the next ridge.  Six minutes later I had climbed 3,000 feet and was just below cloud base, at 2,900m MSL.

A lot of blue sky to the south early in the flight while over-development appeared quickly to the north.

I headed west towards Schladming but could not find any lift above the next two ridges.  A towering thundercloud enveloped Dachstein, on the other side of the valley, approx.  15km away.  I suspected that it sucked all the available energy in its direction, leaving nothing for me to climb in.

Darkening skies to the north west

I decided to turn around and found the good lift just where I had left it 20 minutes earlier.  Back at cloud base I crossed the Enns Valley and found my next climb right above the summit of Grimming where I climbed to 3,100m.

The next line of clouds was 10km NNE.  It was already quite dark but I still found lift under the street as I headed east past the town of Liezen.  Rain began to fall and I continued further east where I found a weak climb above Dürrenschöberl.  Another dark cloud promised strong lift 12km further east above Admonter Reichenstein.

5 m/s (10kt) lift under a dark cloud street

It took me less than 5 minutes to get there and I could observe the cloud getting visibly darker as I approached.  Just when I thought that I was connecting with lift, the cloud’s development peaked and rain mixed with hail started to fall.  I turned the ship around in no time and headed back to where I just came from.

First rain is falling as I’m cruising under a cloud street.

I wasn’t sure whether Dürrenschöberl would continue to provide lift.  Technically I was still within glide range of Niederöblarn but the only route to get there from my altitude would lead through the military airspace around Aigen, which meant that I would have to ask for clearance to cross it.

Just as I was about to look up the radio frequency of Aigen, I connected with strong lift again.  Once again I climbed 3,000 feet within 6 minutes, gaining ample height to stay clear of the military airspace.

The towering cb cloud in the background (where heavy rain is falling) made me decide to land. The airport is in the valley in front of the mountain (Grimming) center-right. The storm cell was approx. 10-15 km away from the airport and slowly moving in its direction.

The skies were now rapidly overdeveloping almost everywhere.  I headed back towards my initial release point above Karlspitz where I could see a monster of a cumulonimbus cloud towering to my right, north of the airfield behind the Grimming.  Rain was also falling to my left.

The only area that still looked promising was further west on the south side of the Enns Valley.  I had to decide whether to continue my flight in that direction and wait for the storm to pass or to get down and land before the storm would reach the airport.

I radioed ground operations with my intention to return immediately and land within 3-5 minutes.  Two minutes later I entered the traffic pattern, having lost 3,500 feet.  At this point the wind had picked up and ground operations had asked all planes to return to the airfield immediately.  I waited for other traffic to clear the runway and managed to spot-land the DG 1001 in turbulent north-westerly winds less than three minutes later.

The flight track is here.

Lessons Learned

  • Pattern practice pays off.   We all practice takeoffs and landings a lot during initial training.  After that we don’t do it nearly as often.  We might fly 50-100 hours in a season but if our average flight is 5 hours long this may only entail 10-20 takeoffs and landings.  Having practiced 25 landings in 2 days for my self-start license prepared me well for landing a completely different ship in challenging conditions.
  • There’s a fine line between strong lift and hail. The development of thunderclouds in the mountains can happen very quickly.  One minute a cloud is still fully developing and producing very strong lift, and one minute later heavy rains and even hail can fall from it.  Never count on a rapidly developing cloud to provide needed lift as you may be forced to fly away from it before getting a chance to climb.
  • Don’t dilly-dally when a storm is approaching the airfield.  When I spotted the towering cb 15 km northwest of the airfield I had to make a quick decision: land immediately or fly west and wait for the storm to pass. I believe either decision was acceptable under the circumstances. (I opted for the immediate landing because of the possibility of additional storms.) But making and executing a decision quickly was important so I could avoid a situation where I would have been forced to land in dangerous conditions.

Low And Slow – But These Views!

August 12 was my second day flying in the Alps this year.  The forecast conditions were rather poor, which surprised me because a cold front had passed through the day before, finally putting an end to the oppressive heat wave that had lasted for more than three weeks. Post-frontal weather often offers good soaring in the Austrian Alps.

Intimidating mountains in western Austria, south of Zell am See.  Note:  I did not take any pictures during the first 2 hours of the flight: I was way too busy trying to make progress while looking for weak lift just a few hundred feet above the ridges.  Conditions improved drastically after 2PM.

The local forecast from AlpTherm predicted weak (“schwach”) climb rates around 1 meter/second (2kts) with thermals up to 3,000m (10,000 feet).  SkySight was more encouraging, indicating a potential flight distance of 400-500km (in an 18m ship) supported by a long soaring day starting as early at 10am, 1.5 – 2 m/s thermals, nice cumulus clouds, no OD, no storms, and no significant high-cloud obstruction. Light southerly winds would contribute to dense clouds stacking up on the south side of the Alps’s main spine, but were likely too weak to be usable for ridge soaring. SkySight projected even lower cloud bases than AlpTherm at the east side of my soaring area – as low as 2,400m (8,000 feet) – yet gradually rising to 3,300m (11,000 feet) further west.

Potential flight distance of 400-500km within the soaring area along the Salzach and Enns Valleys.

My drive to the airport started at the southern side of the Alps under a layer of dense clouds. As I crossed to the north at Wald am Schoberpass, the clouds gave way to deep blue skies.  The air was also much clearer than in recent days: obviously the cold front had removed the inversion layer.  A few low-hanging clouds clang to the slopes of the mountains, remnants of the moisture that the heavy rains of the passing cold front had left behind. There was no doubt that the sun would quickly dissolve them.

Dark red colors show dense cloud coverage forecast south of the Alp’s main spine. Nice cumulus clouds were projected to mark the lift within my soaring area.

By 10:30am the first new wisps started to form above the hills, indicating that lift was already starting to form.  I moved the glider out onto the grid at Runway 04 while the air on the ground was perfectly still.  I was confident that it would not take long for the valley breeze to kick in.  At 11:30am the windsock finally came alive – a clear sign that it was time to launch because the thermals above the hills were sucking in air from the valley below.

Projected thermal strength of 1.5 m/s to 2 m/s (3 to 4 kts).

I was number three on the start list and airborne by 11:44AM.  Once again I asked to be towed to the trusted release point near Karlspitz at 1,800m MSL (6,000 feet), around 1,100m (3,300 feet) above the valley floor, where I released in the first lift above the ridge seven minutes later.

Thermal height projected at 2,400 – 3,000m (8,000 – 10,000 feet) within my soaring area – gradually improving from east to west.

Unable to climb from my release point at less than 300 feet above the ridge I thought I might have released a tad too early when a thermal above the nearby hill Zachenschöberl lifted me to cloud base at 2,400m MSL (8,000 feet).  My average climb rate was 1.5m/s (3kts) – not bad considering that the day had only just started.

The local Alptherm forecast projected weak (“schwach”) climb rates of only 1 – 1.5 m/s (2-3 kts) for most of my soaring area.

I had set a tentative turn point 126km further west above Pass Thurn.  To get there, I would have to first fly along a mountain chain called the “Schladminger Tauern”, followed by the “Radstädter Tauern”, and eventually the Hohe Tauern.

The first reasonably strong climb that allowed me to take out my camera came after two hours into my flight – above the peak of Bernkogel – west of the village Dorfgastein (in the valley below). Note the steep switchbacks of the hiking trail on the face of the mountain.  Climbing is so much easier in a glider!

The peaks of the Schladminger Tauern and the Radstädter Tauern top out at about 2,850m (9,500 feet).  The ridge lines along the foothills are typically about 1,800 to 2,400m high (6,000 – 8,000 feet).  Every 5-8 km or so I would have to cross one of these ridges.

A cloud base of 2,400m did not leave a lot of wiggle room: I would have to climb to cloud base above a ridge line, glide through sink to the next ridge, hopefully arrive there with a decent safety margin, find a climb that would take me back to cloud base, fly through sink to the next ridge, and so forth.  To make progress, pretty much every ridge line had to offer a climb and I would have to be able to locate it quickly once I got there.  Should a ridge not work upon arrival, I would have to follow it towards the main valley (perpendicular to my intended route) and look for climbs along the way.  Should I find myself unable to work my way back up, I would eventually have to land at one of the few land-out fields in the main valley.

The cloud bases lifted to 3,300m (11,000 feet) by mid-afternoon – still well below some of the highest peaks of the Austrian Alps.

Eventually I would get to the “Hohe Tauern”, which were much taller with peaks around 3,600m (12,000 feet).  Low hanging clouds, tall mountains, and soaring don’t mix very well; therefore, I planned to cross the Salzach Valley around Zell am See to the north side and then continue along the lower Kitzbühler Alpen, which top out around 2,500m (8,300 feet) until I would get to my turn point.  From there I would retrace my route back towards the east, continuing on to a second turn point at Admonterhütte near the town of Admont and then return back to Karlspitz for a total task distance of 325km.  That was the plan.

As I headed out on task I observed a seemingly endless line of clouds along the south side of the Alps, just as Skysight had predicted.  On the north side, where I was flying, small but pretty cumuli started to form right above almost every ridge line.

Circling in nice lift late afternoon when conditions were great and soaring was easy. You can see the dense line of clouds in the background on the far (i.e. southern) side of the mountain range. These clouds prohibited a crossing of the Alps to the south and did not dissolve until late in the day.

My first ridge to cross would be near the peak of Gumpeneck, 2,226m tall.   I had hoped to arrive just at the level of the peak, high enough to connect with the thermal breaking off the mountain.  However, when I got there I was down at 2,080 meters, just a little too low to get into lift.  That meant plan B: follow the ridge out towards the Enns Valley.  Only one kilometer later I found weak lift above the ridge, worked my way up to to 2,300m, flew back to the Gumpeneck, and climbed back to cloud base at 2,370m.  On to the next ridge!

I arrived 130m AGL (400 feet) above the next ridge and quickly found the next climb, which took me from 2,200 to 2,570m.  Great! The cloud bases were getting higher. Onwards!

The next ridge was 2,200m high.  I arrived there 300 feet above ground, following along the ridge for about 2 kilometers but did not find a climb.  Time for plan B again: change direction, and fly above the next lower ridge line out towards the Enns Valley.  50 meters AGL I found the next climb, taking me from 2,150m back to cloud base at 2,480m. Time to push west again!

Cockpit view of the LS4. Cruising at 150 kph only became an option by mid-afternoon when the cloud bases were well above the ridges. Earlier in the day I was scratching along from one ridge to the next at 110-120 kph.

The next two ridges were good enough to maintain altitude but provided no climb. I was only 1 kilometer north of a peak that was 2,450m tall – too high.  The lift was probably above the peak but I was down at 2,350m and couldn’t get there. So I continued on.

The next ridge was slightly lower at 2,150m.  I got there 100m AGL and found a nice climb back to cloud base at 2,580m.

This is how my flight towards Zell am See continued.   I found climbs to cloud base above each of the next three ridges, then skipped a ridge and had no choice but to take the next climb back to 2,500m even though the climb rate was dismal.  A fun way of soaring but mentally very demanding. And so slow!

The mountain chain in the center is Hochkönig. On the back side is the city of Berchtesgaden in Germany.

Then came the next ridge and finally some reprieve: my first 2 m/s (4kt) climb  of the day took me to a new high: I was at almost 2,900m!   The airport of Zell am See was now within easy glide range and I could relax a bit.  But I was already 90 minutes on task and had only covered just a bit over 50km!

I continued to push on and the flying finally got faster and easier.  Climb rates continued to improve and the cloud bases increased further.  The additional altitude gave me room to increase my inter-thermal cruise speed from 120 kph to 140 kph.  Above Bernkogel I averaged 2.5 m/s and climbed to 3,050m. Oh what luxury!

Finally I had time to look ahead towards TP1.  At least in theory there were two ways to get there: 1) continue on the south side of the Salzach Valley and cross to the north side near TP1; or, 2) cross to the north side near Zell am See (as I had initially planned) and then continue along the Kitzbuühler Alpen.

The southern route looked very challenging: the mountains to my left were intimidating: the peaks towered high above my glider and were well above cloud base.  The ridge lines ahead were short and provided few options to find good climbs. There was still some wind from the south and I dreaded the prospect of flying in the lee of these monsters.  Unfortunately, the northern route did not look very promising either.  The sky in that direction was mostly blue and the cloud bases were much lower.  Crossing over to the north looked straightforward but would I be successful in crossing back south?  I didn’t know.

The town of Zell am See is below in front of the lake (Zeller See). You can spot the runway of the local airport in the foreground on the right – like Niederöblarn one of the most popular and most scenic glider ports in the Austrian Alps.  The hills on the left side are part of the Kitzbühler Alpen – the cumuli on that side were few and far between and the cloud bases lower.

For a while I contemplated my options.  The airport of Zell am See – one of the premier soaring sites in Austria – was right below and provided an easy and safe landing option in case my adventure to the north side did not work out.  However, I could not see any other gliders around, which caused some doubt in my mind regarding the conditions on the south side.  Also, it had already taken me more than two hours to get here and I didn’t know how long it would take to get back.  It was 2:15PM and Skysight had predicted thermal activity to weaken considerably as early as 4PM.  Ultimately, the doubtful voices prevailed. I decided to abandon my task and turn around.

In hindsight, my concerns were probably overblown.  Conditions continued to improve.  I averaged almost 3 m/s on my next climb and reached 3,150m.  Finally I was able to skip some ridges if the attainable climb rates did not reach my expectations.  My average speed, which had only been 56 kph on my outbound leg, improved to 78 kph on my next leg.

Another amazing look into the steep and narrow valleys of the Hohe Tauern (High Tauern) – Austria’s tallest mountain range.

Once I was back within final glide range to my start airport in Niederöblarn I reversed course again to head back west to see if I could further improve my average speed.  Indeed: on my second westbound leg that took me back to Zell am See again I averaged 82 kph.

I briefly thought about continuing to TP1 now as the Kitzbühler Alpen looked considerably improved, but it was almost 4PM and prudent caution won again.

And another look at Zell am See at the foot of the high peaks on the opposite side of the Salzach Valley.

I had not anticipated that things would get better still until thermal strength peaked around 4:30PM.  On my second eastbound leg I averaged 105kph.  I started to wonder if I could even score for the OLC Speed League despite the excruciatingly slow start.

Around 5PM, however, it quickly became obvious that the day was coming to an end.  I crossed the Enns Valley, found another climb over the Grimming and added a sightseeing flight along the Northern Limestone Range.  I had hoped for a similar late-day “radiation-lift” effect from the steep south-facing cliffs as  I had noticed on my prior flight on August 4.  However, this time the air along the shaded cliffs just produced sink.

View of the Dachstein Massif from above Planai Peak (directly below). The world cup downhill ski racers start at the top of the mountain that can be seen in the bottom left corner of the picture. This downhill track was long the fastest in the world.

Near Dachstein I crossed the valley again and found the day’s last thermal over Planai Peak, famous for world-cup ski racing.   From there I followed the ridge lines, which had become completely still, back to the airport in Niederöblarn for one of my smoothest touch-downs ever in completely calm conditions just before 6PM.

View towards the west as the clouds started to dissolve in late afternoon.

Total flight distance 392km.  Average Speed, unsurprisingly slow, at 68.5 kph. The flight track is here.

Lessons Learned

  • Flying low is (mentally) demanding.  The work load is dramatically higher when you have no choice but to fly low.  Having a plan A (where to go for lift), a plan B (where to go if lift does not materialize), and a plan C (where to escape to – if necessary to land – if plan B does not work) is critical.  And what your plan A, B, and C ought to be changes constantly.  I.e., every few minutes you may need to formulate a new plan A, B, and C. That’s a lot of work.
  • Lift above the ridges can be very narrow.  I noticed that the lift close to the ridges can sometimes be just a thin band that may be impossible to circle in.  If it is wide enough to circle a steep bank angle (40-45 degrees) is often required to stay in lift – also and especially because you can’t afford to get close to minimum speed while in close proximity to the terrain.  Two or three times I found myself circling with other gliders who ended up dropping out of the lift because their circles were just to wide.
  • Always arrive above the ridges.  Hopping  from ridge to ridge only works if you can be sure of arriving above the next ridge line, ideally above the highest peak along the ridge for that’s where you will most likely find the next climb.  If you’re not 100% certain of that, than your plan B must include a path over another (lower) ridge line that you can reach for sure above the ridge (plan B) and from where you can escape to a landable area (plan C).
  • Always watch your airspeed as you approach a ridge. When you are approaching a ridge close to terrain you might intuitively pull back on the stick and inadvertently reduce your airspeed.  Never let that happen. Flying close to terrain is dangerous and flying too slow and too close to terrain can be a fatal combination.  I kept reminding myself of this throughout the flight.
  • The combination of low cloud bases and weak lift makes you SLOW.  The obvious part of this is due to the fact that you take a long time to circle in weak lift and that you have to maintain a modest airspeed even in cruise mode. Less obvious are the other delays: i) you have to take (almost) every climb simply because it is still better than plan B. ii) And if plan A does not work you may be forced to significantly detour from your intended flight route simply to find the next climb and stay aloft – as a result you end up flying many more unintended miles along the way and this is what really slows you down.
  • Skysight has been remarkably accurate.  Always read any forecast with some skepticism and never expect it to be 100% correct in every respect.  However, once again Skysight was very close to reality:  e.g., by mid-afternoon, climb rates were a little stronger than forecast and cloud bases a little bit higher.  The most clouds were almost exactly where Skysight had predicted them to be. The start and end of the soaring day were both perhaps 30-45 minutes later than forecast.  The southern side of the Enns Valley worked a bit better than forecast and the north side a little worse.  But overall, Skysight was remarkably on target.  Having worked with it now in different geographies and widely different conditions I believe it’s the best soaring forecast out there at the moment.

Along the Spine of The Alps – Soaring from “Bone to Bone”

Europe is enduring a pro-longed heat wave with near record high temperatures from Portugal to Austria.  That means the nicest place to be is right at cloud-base where the temps are much more comfortable.

At cloud base above the Central Alps in the middle of Austria. The Tappenkarsee is below. The peak to the left is called Faulkogel, 2,654m (8,700 feet) MSL. Where else would you rather be?

This past Saturday promised nice soaring conditions in Central Austria:

Moderate thermal strength of 2 m/s (4 kts)…

… cloud bases around 3,000 meters (10,000 feet) …

… high probability of cumulus clouds marking the lift …

… only modest risk of overdevelopment …

… a moderate risk of thunderstorms mainly confined to the area north of the northern limestone range …

… hardly any wind within the boundary layer …

… convergence lift of 1-2 kts along the spine of the mountains (as a result of the valley breeze that lifts air along the slopes of the mountains, converging and rising off the tops of the ridge lines) …

… no high clouds shielding the sun …

… culminating in a projected attainable flight distance of 500-600 km in an 18 meter glider.  (I was flying a club class ship with a projected attainable flight distance of approx. 400-500km).

Skysight’s predictions were also confirmed by the local soaring forecast from Austrocontrol, which projected:

“Good” thermal conditions in line with Skysight’s prediction of a thermal strength of 2 m/s (4 kts), …

… a trigger temperature of 24 degrees C, expected to be reached as early as 7 am (!), and a maximum thermal height of approx. 3,300m (11,000 feet) MSL.

Considering the consistency of both forecasts, I thought it appropriate to plan my first pre-declared 300km triangle in the Alps:

  • Start above Karlspitz, approx. 7 km south of my launch point at LOGO (Niederöblarn airport).  This is the location of one of the “house-thermals” and a frequent release point for gliders flying from LOGO.  From there I would head 85 km westward towards …
  • … TP1 near the village of Wörth in the province of Salzburg at the foot of Austria’s tallest mountain, the Grossglockner.  The peak of Grossglockner (3,798 m or 12,461 ft) was well above the projected thermal height and likely unattainable.  A second eastbound leg of 156 km would take me to …
  • … TP2 above the village of Vordernberg, in the province of Styria near the town of Leoben. And from there it would be 69 km to the …
  • … finish line, once again above Karlspitz.  Total task distance: 311 km.

Task as shown on Google maps.

I had reserved the LS4b of the fleet of Niederöblarn.  It’s a very comfortable club class ship with a performance slightly worse than that of the Discus that I’m usually flying from Boulder.  Since I had not flown in Austria in more than 12 months I had to take two brief check-rides in the DG 1000 with a local instructor.  This was a nice opportunity to refresh my spin training (a lot of fun!) but it meant that I wouldn’t be able to launch on my own before noon.  Given my relatively late start, the 300km task distance seemed appropriate.

I released near Karlspitz a few minutes past noon and rounded the start sector above the peak four minutes later at an altitude of 2,200m MSL.  I followed the ridge line to the SSW to further gain altitude.  One of the great phenomena of flying in the Alps is the amazing predictability of thermal lift directly above the ridge lines, especially in low-wind conditions and in the middle of the day when the sun heats both slopes equally: warm air rises up along either side of the ridge and when it reaches the top of the ridge line, both streams converge and the air has no place to go but up.

The lift is not necessarily consistent, but it often averages 1-3 kts, which is usually sufficient to maintain or even slightly gain altitude as long as one flies directly above the top of a ridge.  Thermals will then break off the ridge line as well, usually above distinctive peaks.

The flight track off tow shows how I’m following the ridge line. It’s often easy to maintain altitude when flying along the top of the ridge (up to about one or two thousand feet above the ridge) and it’s a great strategy to identify the best thermals – especially in blue conditions – as they tend to break off from spots directly along the ridge.

View from Mausgarkopf (below) to the north across the Salzach Valley towards Hochkönig in the distance (above the wing tip) – near TP1. The line of clouds in the background is approx. over the border between Austria and Germany and confirmed the higher Cape index forecast for that area. The ridge line below the wing is a good example of where to find lift: the sun heats the slopes on either side of the ridge. That means air ascends on both sides and then lifts off the ridge top. The best thermals tend to be above the peaks.

The main spine of the Alps resembles a giant fishbone.  The spine itself is the ridge line in the center, which is in the direction from west to east.  On either side of this main ridge are individual ridges (i.e. individual “bones”) protruding north and south with steep and narrow valleys in-between.   Soaring usually involves a series of valley crossings as you’re flying from one of these bones to the next.  More often than not, the valley crossings involve significant sink, while the lift is concentrated above the bones.

The fishbone structure of the Alps is easily visible in the Google Maps image.

Cloud-bases tend to be much lower than in the western United States and are often not far above the ridge line.  Arriving below a ridge line can mean trouble (because usable lift is sometimes only available above the ridge-tops), so the safest strategy is to ensure that you’re high enough before leaving a ridge and heading through the sink to the next.  Depending on the height of the cloud base and the performance of the glider it is often possible to skip one, two or several ridges before taking and centering another climb.

The village of Bad Hofgastein is below. In the distance is Austria’s tallest mountain, the Grossglockner.

In the western US my cross-country flight path is predominantly determined by the location of the clouds (and the terrain is often secondary – especially if it is many thousand feet below), whereas in the Alps, the terrain plays a much more prominent role in determining the optimal flight route.  Obviously, that doesn’t diminish the  importance of clouds as a marker of thermals. However, I have found that clouds that have formed directly above the ridges but have drifted away with the wind are often no longer marking usable lift. The ridge itself, on the other hand, is often still producing lift even if no cloud has yet formed to mark it.

Cloud shadows above another ridge. Compared to the Western US, the thermals in the Alps tend to be narrower and closer together.

Just before TP1 I found myself circling with three raptors – possibly small eagles – at an altitude close to 3,000m (10,000 ft).  One of the raptors must not have attended flight school as it changed the direction of turn and started to circle in the opposite direction. I saw the bird coming straight at me and remember watching it to see how it would react to my presence.  Fractions of a second later, just when I was surprised that it would dare come so close, I felt a bang as it collided directly with my left wing.  My Oudie flight computer, which was only attached to the canopy via suction cup, fell off on impact and landed in my lap.  My adrenaline rushed and my first reaction was a mix of empathy for the bird, which must have lost its life, and concern for the integrity of the glider and my own safety.  I looked out at the wing and saw to my relief that it was still in one piece and that there was no obvious damage.  I tested the controls and confirmed that the glider reacted just as I expected it to. Where the bird had struck, approx. 3m (10 feet) from the root of the wing, I saw a shiny spot on top of the leading edge of the wing. But there did not appear to be any dent or some other form of damage. Not knowing what else to do, I kept circling for another few turns, while I tried to decide whether to cut my flight short.  After inspecting the wing as best I could and confirming again that everything was working just fine, I ultimately decided that there was no reason to change my flight plan, and thus I continued on route.

Flight path to and from the first TP.  Flight from “bone to bone”: all climbs are directly above the ridge lines. I did not skip any of the “bones” to stay high and keep the airport in Zell am See within easy glide range as there are no viable land-out fields in this area.

I reached TP1 70 minutes after leaving the start line 85km earlier.  The average speed of 72 kph was not particularly high but – except for the bird strike – my flight had been stress-free despite the relative lack of land out opportunities.

View of the “Glocknermassif” at the intersection of the provinces Salzburg, Carinthia, and Tyrol. Cloud bases were higher in this direction but the tallest mountains were obscured and the peak of the Grossglockner appeared to be out of reach.

TP1 was only 25km northeast of Austria’s tallest peak, Grossglockner, 3,798 m (12,460 ft) high.  Cloud-bases at my location were around 10,000 feet. Even though the bottom of the cumuli was someone higher to the southwest, Grossglockner was obscured by clouds and appeared to be unattainable.  There was a chance that the cloud base would lift later in the day but I decided to turn around and continue on task.

The posh skiing village of Badgastein is below. To the left are the high peaks of the Ankogelgruppe. The mountains in the distance on the far right are in Northern Italy.

Looking at the sky ahead of me I had to make a decision: should I continue on the north side of the central spine of the Alps (essentially retracing my flight path), or should I follow an almost continuous line of clouds that were perhaps 15-20 km further to the south.  The southern route looked much faster and easier but I had not researched the land-out fields to the south (except for the airport of Mauterndorf where I obtained my winch training back in 1984).  There was also a military air space around Zeltweg that I suspected to be inactive on the weekend, but I did not know the proper radio frequency to verify this.  Looking at the clouds I could not tell for sure if I would be able to follow this line without encroaching on the military airspace. Thus I decided to fly on the north side.  The main challenge was that the cloud coverage in this area had become very scattered with large blue holes on course.  Well aware that my average speed would suffer, I decided to maintain my strategy of staying high and keeping known airfields and land out spots within glide range at all times.


En route to TP2 looking NW. Big sections of the sky were blue along this stretch. The town of Trieben is below in the Palten Valley at the foot of the Reichenstein. The mountain to the right is the Hochtor.  I crossed the valley approx. 15 km further southeast.

The execution of the plan worked as expected.  I found practically all the climbs directly above one of the ridges, usually above one of the mountain peaks. There was a major variability in climb rates.  Sometimes I would average 3-4 m/s (6-8 kts), sometimes as little as 1 m/s (2 kts) or even less. With mainly blue skies ahead of me there was no way of knowing how strong the next climb would turn out to be.  My conservative strategy worked but my progress was predictably slow.

Just after crossing the Palten-Liesing Valley, looking north. The two parallel mountain chains in the background are traversed by the river Enns in a deep and narrow gorge – the “Gesäuse”, one of Austria’s National Parks.

Another obstacle on course was the crossing of the Liesing-Palten Valley.  As I approached the valley I noticed a nice cloud right at the top of the divide at Wald am Schoberpass.  However, as I got closer, the cloud was dissolving and I decided to stay on the west side, gain additional altitude, and cross further to the south.

Stadelstein, Hochstein, and Schwarzenstein are below. The open iron ore mine called Erzberg (“ore-mountain”) is visible center right. In the background are the Wildalpen (“wild alps”).

The crossing was uneventful. I ended up loosing less altitude than I had expected.  But there was a lot of traffic in this area.  I encountered seven or eight other gliders as well as hang gliders and paragliders.  Most gliders in Europe are equipped with Flarm systems but  hang gliders and paragliders are not.  Traffic density in the Alps is orders of magnitude higher than in the American Rockies.  Paying close attention is paramount at all times.

The free-standing mountain in the center is called Gößeck. The Liesing Valley that I crossed earlier is right behind it.

TP2 turned out to be well-picked as the sky further east was significantly overdeveloped with some emerging storms. I rounded it just before 3PM in the afternoon.

The road over the Präbichl mountain pass is below. This is were I learned to ski at the age of three. In the background is the Hochschwabmassif. TP2, the village of Vordernberg is in the valley just to the right edge of the picture. I considered pushing further east to extend the flight but this area seemed to be rapidly overdeveloping and so I decided to stay on route after rounding my turnpoint (indeed there were heavy rains in this area less than one hour later).

Cloud bases on the east side of the Liesing valley were significantly lower and now I had to transition back to the west side.  Concerned about arriving too low I ended up wasting more time in weak lift before crossing the valley again.  Again, my hesitation turned out to be overly conservative.  After the crossing I quickly regained my altitude and was back at cloud base.  I was also on final glide even though I had almost 50km in front of me.

I got another good look at the open iron ore mine of Erzberg as I circled above the Eisenerzer Reichenstein to gain height in advance of my second crossing of the Palten-Liesing Valley.

With my goal already made, I finally started to fly less conservatively.  I flew 170 instead of 140 kph in-between thermals, skipped several ridges, and only took the strongest climbs.  This strategy would likely have worked for much of the entire flight and would have resulted in a significantly higher average speed.

I finally reached the finish line after 4 hours and 40 minutes with an average task speed of 67 kph.  Slow, but stress free, and happy to have completed my third pre-declared 300km goal flight and my first in the Alps.  🙂

After crossing the finish line I traversed the Enns Valley and continued to fly west above the tops of the Northern Limestone Range (Nördliche Kalkalpen). The Dachstein Massif is right in front.

After completing the task I took another climb and decided to add some sight seeing on the northern side of the Enns Valley.

The small remnants of the Hallstädter Glacier are on the right edge of the picture. When I was a little kid, the glacier was much thicker and wider flowing down into the valley below. Directly behind the peak in front I got a glimpse of the Hallstädter See (Lake Hallstatt), one of the most picturesque lakes in the entire Alps and a UNESCO world heritage site. Many of my American friends know it from their Sound of Music tours. 😉

I crossed to the Kammspitze, climbed again and headed west over the Scheichenspitze, the Hohe Dachstein (the highest peak of the day at 3,004m or 10,000 feet), and the picturesque Bischofsmütze.  From there I retraced my flight path below the level of the peaks.

The prominent Bischofsmütze (Bishop’s Mitre) is in the center. The valley behind it leads to the city of Salzburg.

This final section turned out to be the most scenic and enjoyable part of the flight.  I was flying along the steep south-facing cliffs of the Northern Limestone Range (Nördliche Kalkalpen).

The south face of the Dachsteinmassif was aglow in the early evening sun. The cliffs were still emitting heat and producing great upslope lift close to 6pm in the evening.

These cliffs had been exposed to the sun for the entire day and were radiating heat that caused the air to ascend along the slopes at 1-2 m/s allowing me to fly along the entire range at about 130-140 kph without loosing altitude.  I even ended up climbing above the top of the Grimming, all in straight flight for about 50 km.

Nice view across the back side of the Dachsteinmassif. This high plateau sits about 6,000 feet above the floor of the valleys. You do not want to get caught low above it in a glider as there is no way out.  The mountain hut below is the Guttenberghaus – you can see the very demanding hiking trail hewn into the cliffs at the bottom left of the picture.

Unfortunately, this last section did not count for the OLC Speed League because I omitted climbing back another 300-400 feet at the end (which had been my low point earlier).  There’s no doubt that the final 2 1/2 hours were easily the fastest of the entire flight (probably averaging more than 100 kph).

The upslope lift along the cliffs took me above the top of the Grimming, the beautiful and prominent mountain next to the airport of Niederöblarn.

Overall, I had a very nice and relaxed flight in good conditions.  I’m happy with the result especially considering my conservative tactics and the fact that my speed was right in line with that of others flying in this area on the same day.  My flight track is here.

Lessons Learned

  • Follow the ridge lines whenever possible.  When the sun heats the slopes on both sides of a ridge, warm air will ascend and converge right at the top.  The best thermals will also almost always break away from the top of the ridges, usually above prominent peaks rising above the ridge line.
  • Lower may actually be faster.  You may be able to fly directly along the top of a ridge line without losing altitude.  This type of lift works best in relative proximity to the terrain, i.e. a few hundred feet above the ridge, but not several thousand feet above.  This means you are likely to fly faster if you fly lower. This is at first counterintuitive because you can’t take advantage of the fact that the delta between IAS and True Airspeed increases the higher you fly.  (This is a big contributing factor to the high average speeds in the American West.) Obviously, flying low above the ridges is mentally demanding and implies a reduced glide range requiring great situational awareness with respect to land-out fields and any terrain obstacles that may get in the way.
  • Arrive well above the ridge top when flying from “bone to bone”.  The fishbone structure of the Alps makes constant crossings of narrow valleys inevitable if you want to get anywhere.  Thermals almost always break away from the ridge tops and it may be difficult to find lift if you drop below ridge-line. So don’t, especially if the wind is insufficient to produce usable ridge lift helping you work your way back up.
  • Terrain is at least as important as clouds. Sunny ridge lines are constantly generating lift and new thermals will periodically break off from the ridge tops.  These thermals can drift away with the wind and I have found that they often are no longer working once they have moved away from the ridge that spawned them.  You are more likely to find lift in the blue above a ridge line than under an aging cloud drifting away from a ridge.
  • Rocks store heat extremely well. The south facing cliffs along the northern limestone range stored a ton of heat energy throughout the day.  Flying in constant lift along the face of the cliffs at the end of the day was an amazing experience.  However, remember that whenever you get close to terrain it is paramount to fly at a safe speed and to know the locations of cable cars and similar obstructions as they are very difficult to see from the air.
  • Birds can be stupid.  I have always admired birds for their maneuverability and I never thought that a bird would be so stupid as to directly collide with a glider. But apparently that can happen. It’s a good thing that gliders are pretty sturdy.  However, I hate to imagine what would have happened if the bird had collided straight with the canopy or the horizontal stabilizer.
  • Traffic!  The air along the spine of the Alps is very busy – especially compared to the empty skies above the Rockies.  During my flight I encountered at least two or three dozen other gliders in addition to para gliders and hang gliders. Especially the latter are not equipped with Flarm systems and it’s critical to keep your eyes outside the cockpit at all times and pay close attention to other traffic.
  • Mind the altitude rule for the OLC Speed League.  The last 100 km of my flight were by far the fastest of my entire flight but they did not count for the OLC Speed League because I didn’t climb back to my previous low point during the flight.  I would have scored considerably better had I climbed back another few hundred feet towards the end before coming back down to land.  It is actually beneficial to have more altitude variability throughout the flight as this allows for more opportunities to calculate the fastest 2 1/2 hour segment of the flight. Something to remember.