Thermal Soaring and Foraging Behavior

Animal, Cute, Eat, Eating, Forest, Fur, Furry, Mammal
Sourced from here.

Think of your favorite little furry animal. It burns energy all the time in order to stay alive. In order to get more energy, it must travel to places where it can find something to eat. It will spend time at those places, foraging for food and eating. Either when it is satiated, or when the cost of trying to get more food out of a given source becomes too high, it will move on to another food source.

It will have to scurry a certain distance to get to that food source. If this distance is high, then animal is in trouble for it will have little energy left by the time it gets there. If the distance is low, then the creature can be rightfully said to be “fat, dumb, and happy.”

What I just described is broadly an example of “foraging behavior”, something studied by ecologists. These are scientists out there who track animals and watch how they manage the problem of finding food and staying alive.

It probably does not take too much imagination to see how foraging behavior relates back to soaring. A pilot forages for energy by finding thermals, but instead of metabolizing energy biologically, he simply glides it out to the next thermal source. He forages for sites that are worth his time; thermals that are too far away, too weak or the like are not worth the trouble (usually!).

Even some equations in foraging theory have direct similarity to soaring, such as the prescient Marginal Value Theorem (pMVT). This dictates that given perfect information the time to leave a foraging source is when an alternative future source will provide more energy than in the immediate present state. This sounds a lot like MC theory! Leave the current thermal when your climb rate gets below the average expected climb rate for your next thermal. And interestingly enough, this model does a pretty good job of describing the point at which animals leave to a future foraging site.

So looking at foraging behavior, it provides another good analogy as to how glider pilots manage the optimization of climbing and leaving a thermal. Exploit lift until it gets weaker than a future thermal. Explore for an alternative once you cross a given threshold. Simple enough.

However, things get interesting when you start fiddling with the distance between foraging sites. For instance, suppose that there is no possibility of finding any more food beyond this point. It’s winter and your furry animal is at the last food source available. The conclusion is to tank up as much as possible and hope that this will last the creature through the dry spell. This is a similar deal when you have a distance day on a thermal flight and you’re in the last, weak bubble of the day. Take as much as you get and accept that this the best you will do.

But what happens when you’re not really sure whether there will be food at the next foraging sites or not? You go from place to place and you find one empty and another one too. You might even run out of energy and starve!

Suppose you recognize that there is a reasonable possibility that all possible foraging sites may run out while you’re still at a food source. How would this change your behavior?

My guess is that you would take everything you can get out of current foraging sites, accepting greater costs to do so. Your furry animal will eat every scrap off food here, even if its more work to do so. If you look ahead and see a sky that’s decaying and you suspect that this thermal may be your last, then you will be motivated to stay in it, even if its weak. And you will probably do the same thing in the next and subsequent thermal, should you find them and you still judge the conditions to be tricky.

The point is that when the distance that you traverse from a thermal to another thermal is uncertain and may even exceed the total energy you have available, the decision-making is much less straightforward than when you assume you will find a thermal and your goal is to simply optimize the current glide. For people who have followed my writing, this goes back to “Gear Shifting” and my work with John Bird on Bounded Rationality and Risk Strategy in Thermal Soaring. But I figured that this foraging example may be another way to look at risk management in thermal soaring using perhaps intuitive examples and fiddling with their variables.

Falling Off Ridges

Reviewing the Ridge Map, I noticed some appalling landouts associated with ridge flying. Falling off of a ridge is about the most dangerous kind of landout situation a soaring pilot can encounter. When you fall off, you typically have very little time and few options to choose from. Usually you must do an abbreviated pattern into your field. Fields near mountains tend to be shorter and more rolling, also increasing risk. These factors require serious consideration in order to make a safe landout.

The disturbing feature of many ridge landouts is the tendency of pilots to make *very low* patterns/approaches into fields. A lot of this is due to their attempts to thermal in weak lift after having fallen off the ridge. I suspect that pilots get more comfortable thermalling low when they spend a long time very close to the trees. The same pilots who would quit well above 500ft are attempting to dig out from 300ft AGL! This is followed by a full pattern initiated at 200ft AGL!

However, looking at these trends, I suspect that pilots lack some guidance as to how to properly conduct a ridge landout. As such, here are some thoughts and guidelines to take a very dangerous situation and make it considerably more manageable.


In crucial areas like gap crossings (transitions) or in areas with sparse landing options, it is critical that you know beforehand what your options are. Where fields are sparse, the few fields that are available tend to be marginal. Moreover, you might be forced to make a very low approach into a marginal field that has only one way in. Knowing what you are dealing with and having a plan beforehand can be the difference between success and totalling your glider. When it comes to gap crossings, you might have to make a straight-in into your option. If you know your options and are prepared to do so, your odds of success are a lot better.

There are few landing options in the section between Wind Gap and the Ski Area. Knowing what the options are and how to approach into them can be the difference between success and failure.

Falling off a ridge rarely happens in a heartbeat!

Your situation will slowly deteriorate and you can pick up on this well before you have to commit to a landout. If the ridge is softening up, you will be getting lower and slower. There will be an eery smoothness to the ridge, punctuated by weak little bubbles that hardly improve your energy situation. When you feel this happening, this is your cue to take the next thermal if you find one. At the same time, you should start paying a lot of attention to the fields in the valley below.

Field selection

When the ridge is soft, you should be flying “field to field”. If you’re hanging on the ridge, then keep finding each successive field that you could land in. Should the ridge go from soft to not working, you will be ready to land. Don’t go into an unlandable or marginal area ahead if the ridge is soft!

Remember that many ridge fields can be marginal, so you have to be vigilant in your field selection. Pay a lot of attention to the field’s slope. The best case scenario is that you find a field that has a favorable slope and is perpendicular to the ridge. This way you are on “base” leg while on the ridge. If you choose to commit to the field, then you will have from 500-1000ft AGL to work with, quite reasonable! You will also be landing into the wind, good news! Fields that are parallel to the ridge are fine too, but make sure that you picked up the right side to make your approach.

Falling Off the Back

Sometimes your only good options are on the downwind side of the ridge. These are very tricky situations for several reasons. The first is that you usually have to leave the ridge at a higher altitude than you would if you had a field on the front side. Some ridges have a broad, flat peak and you have to maintain enough altitude to clear over the top of it. This goes back to the business of committing while you still have time and options. Plus or minus 10 seconds can make the difference between clearing the mountain comfortably, to being marginal, to not having enough altitude to make it over. Remember that settling down on the mountain does not happen instantaneously. If the ridge is not supporting you 500ft above, 300ft above, 200ft above, it’s probably not going to do you much good 100ft above the trees. If you’re getting scared, act on it sooner than later.

Secondly, the wind flows on the backside of ridges can be unpredictable and violent. You are heading into the lee sink of the mountain and the wind can curl and do all sorts of wild things. Expect turbulence and sink. Keep your speed up and try to find a large field.

An example of when I bailed off the backside of the ridge. I left with enough altitude to make the options behind Second Mountain. There was a little ridge in the valley, perpendicular to the best landing option available. I found lift over this ridge while in position for my field, S-turned my way up higher until transitioning to full turns, and almost thermalled out. I remain ambivalent over making this decision. But this remains a good example of bailing off the back of a ridge when it is not working well enough.


In thermal soaring, we are trained to transition into “landing mode” at an appropriate altitude. When ridge soaring, we delay this point to an altitude that is considerably lower than under normal conditions. However, the moment you fall off the ridge, this should be your cue to transition into landing mode. Especially if the ridge is weak or you fell off halfway below ridge top, you are likely to be at or below 500ft AGL of the valley floor. You need the altitude to make a safe approach and landing into what is likely to be a trickier than normal field.

Also, the earlier you accept the ridge is not working, the better. If you can’t hang on a ridge 50ft below ridge top, it is probably not going to get better 100-200ft below either. There are exceptions, such as if the ridge is turning toward a more favorable wind angle. But all things being equal, the earlier you accept that the ridge isn’t working, the better. Ridges tend to be sharp at the top and flatter sloped at the bottom. If you leave early, you will maintain a reasonable height AGL, especially if you have to go a ways toward a field in the valley. If you delay several hundred feet, you will be hugging the terrain on your way toward the fields; bad news.

Also, if the ridge is reasonably high, the earlier you leave, the better chance you will have to find a thermal in the valley. Every 100ft makes a big difference in connecting with that thermal. Don’t delay leaving a ridge that isn’t working.

This pilot shall remain nameless. He delayed leaving the SE ridge too long and had a marginal approach into a field. If he left earlier, he could have made a direct approach into Blairstown Airport. Along the way he was barely outgliding the terrain. +- 100ft makes all the difference when leaving a ridge.


Now that you’ve committed to landing and picked out your field, you need to deal with the fact that you will probably have to make a low approach into the field. If you don’t have enough height to make a normal pattern, don’t. It is much better to be higher and do an abbreviated approach rather than a low, full pattern with all the associated risks of a stall/spin.

If I have to use an abbreviated pattern, I like to use the “hangglider technique”. I position myself offset from the field and S-turn until I am in a comfortable altitude to make an approach into the field.

This is a good example of making an S-turn to control for altitude.

In sum, maintain situational awareness of your options, accept defeat early, commit early, and make a safe approach in a field.

Managing Stress in Competitions

My lab invited a very insightful speaker, one who specializes in sports and occupational health psychology. Her area of focus is in how athletes and high-stress workplaces (firefighters, police officers) deal with stress, burnout and engage in recovery techniques.

Naturally, I saw a lot of parallels between her research and glider racing. She makes a very strong case for the need to focus on rest and recovery to achieve optimal performance.

Notes from talk:

– There are several models that describe the stress/recovery cycle. Generally, it is a good analogy to view energy as a limited resource. Recovery serves to replenish the resource. If the subject’s resources get expended quicker than they are replenished, the subject will burn out.

– Burnout/overtraining causes diminished performance.

– Symptoms include: racing thoughts, rumination, fatigue, mood disturbances, lowered vigor.

– Burnout is described like dehydration. By the time you realize you’re fatigued, it’s already too late. Must have proactive strategies for recovery.

– Stress/recovery follow an S-shaped curve.

There’s a threshold of stress that a person can handle, above which it is almost unrecoverable, except if one allows a very long time. (Longer than the time available in the contest).

– Recovery methods include: sleep, relaxation, social activity, cognitive processes focusing on self-control and concentration.

– Emphasized psychological detachment during rest. Need to dissociate from the stressful activity (good and bad stress).

– Preoccupation as an athlete and ones’ performance hurts recovery. It is good to appeal to other forms of your identity during recovery stages.

– When mind races when trying to sleep, a good strategy is to write in a journal. Develop a habit; write down those items and then once journal is closed, it’s done and accounted for.

– Habituation of recovery strategies, especially sleep is very important. Develop a sleep schedule and stick to it. No computers 30 minutes before shut-eye.

Actionable goals and items for contest pilots:

Suggested goals:

  • Start the contest with as much energy as possible.
  • Minimize energy lost on each day.
  • Facilitate psychological recovery strategies for the following race day.

1) Start the contest with as much energy as possible.

  • Arrive as early as possible. Bring all essential hardware and equipment with you. Control for all items that can stress you or otherwise fatigue you. Prepare as much as possible before you arrive, including field selection on final glides, review of terrain, etc. Train before you arrive.
  • The objective once you do is to get the equipment ready as early as possible and do several flights in the local area in that first week.
  • No flying within three days of the contest, if not more. Fatigue builds up over time and it can take a while to recover from the training.
  • Crew should not be a stressor. Ideally, the crew should be a person you are closely familiar. Pilots tend to be introverts… dealing with new people is usually a drain. If anything, the crew’s primary responsibility is to minimize anything that could drain the pilot… dealing with the equipment is just the best way to do that.
  • Minimize conversion in instruments and avionics. There is no need to use unfamiliar units or avionics. If standardized avionics are desirable, recommend to train with them for an extended period of time before the contest. Dealing with unfamiliar units or instruments is an unnecessary drain.

2) Minimize energy lost on each day.

  • Plan on flying at 95 percent of your performance in the beginning of the contest; pace yourself.
  • Good days can be as big or a bigger drain that bad days. Be careful about perpetuating that “high”, “rock and roll” state when in flight. It is really fun now, but it will probably burn you out for tomorrow.
  • Recognize this in the context of strategic decision making. “I can make a bold move now, but at what cost to my overall fatigue?”

3) Recovery techniques

  • Finish flight ASAP. After flight is over, goal is to recharge for tomorrow.
  • Each pilot should have recovery strategy
  • Physical activity can be beneficial
  • Emphasize detachment from soaring related activitiy
  • Social activity is good, if it is desired. Some people need quiet time.
  • Write in journal before sleep.

Emotion Regulation And Decision-Making

Image result for angry cartoon
Cartoon sourced from here.

Being strapped down in a tin can while racing and experiencing things that are not working out for you is emotionally challenging. You see a competitor slip ahead, you fall out of the band, the sky starts deteriorating; all these situations can have powerful emotional effects that can distract you from dealing with these challenges. Being able to minimize negative emotions is therefore quite advantageous to one’s soaring performance.

Psychological research in Emotion-Regulation has some useful insights in this respect. Two commonly studied emotion-regulation techniques are suppression and reappraisal.

Suppression is the act of taking a negative emotion and attempting to minimize it. This is the equivalent trying to contain yourself when you get angry. Studies had shown that trying to minimize the effect of an emotion after the fact is an ineffective strategy.

Reappraisal is the act of reframing your situation in a different light. For instance, if you see high cloud cover move in, you might think that this is an opportunity for you to excel at your weak weather flying while everyone else is going to be scared and suffering.

Research has shown that reappraisal is overwhelmingly a much more effective emotion-regulation strategy. This is because reappraisal has a tendency to take the bite out of the emotional response before it happens; it minimizes the total emotion experienced. As a result, reappraisal strategies could greatly improve performance.

The risk management work that John Bird and I did actually relates to reappraisal. It helps the pilot look at the sky ahead and reason that due to the risk level exceeding a certain threshold, that they must change their strategy. By being able to base risk strategy on something measurable, it allows the pilot to easily reappraise a situation. When it comes time to get into a “risk-minimizing” mindset, it isn’t painful to watch a couple other pilots drive ahead and leaving you behind. Sure, you might be missing out on an opportunity, but looking at the sky ahead, you can just write off those pilots as taking an excessive gamble. As a result, you don’t feel the emotional pain associated with them leaving you behind.

Like many things in aviation, emotion-regulation and reappraisal is part of overall situational awareness. If you judge your priorities correctly and are ahead of your situation, then you will not be as emotionally affected. Conversely, if you are experiencing strong emotional reactions in the cockpit, this is likely to be due to a lack of situational awareness at an earlier point in the flight.