When to Stop for a Thermal | An Algorithm for Speed 

Great video. I'll focus on this approach during the 2024 gliding season.

Great explanation, and love how you incorporated the secretary problem to explain it. Thanks! PS: been gliding for 15 year, soaring cross-country for 12 and instructing for 5

Great explanation, I have to admit I wondered where you were going with the secretaries! I recently learned a nice way to apply McCready: Set it to the value of the climb you would accept in that moment. I think it correlates with height most of the time.

Algorithms to Live By is a great book! After reading it, I was thinking that soaring was a search/exploit problem; do you exploit the thermal you're in, or search for a better one? However, I think the secretary problem is a better fit. Nice job!

My mental picture of thermals (now) certainly aligns with what you explained, Phil (that was very useful knowlege on my flight yesterday). For MacCready, I use a very conservative setting of 4, and for speed to fly - "min sink". For now, anyway. If I'm in a strong convergence line, then 80 to 90 knots. That's a rare thing for me right now, though. At my level of expertise, I'll hire any secretary - as long as she can spell! Great video, Phil!

Wonderful video man! Very nicely explained. I do this buuuut sometimes only in my mind. In my last XC I either completely missed the thermals or totally misread the clouds. Not a single bump - anywhere that I searched. Until finally I was deploying the Solo. 😅 Whenever I have a huge blue zone (that is caused by shadowing, not just flying in the blue) to cross I slow down to best glide if I'm not sure I'll be able to make the crossing.

One of most interesting tips for gliding pilots I have ever found on youtube. Thank you a lot!

Great presentation. Thank you ! Speed to fly, range of thermal strengths, progression of the daily cycle, height bands, polars and MC glide ratios, while assessing the potential of the sky out ahead of the cockpit.....a multitude of variables for thé pilot to ponder during the real time challenge of flying without a motor. You nailed it ! Clear and concise. Johnson stated in the 60´s. Get high, stay high. Getting low and struggling can really diminish your average speed for the day and your achieved distance total. Loved the video

Excellent video! I strive to apply this strategy as well (easier said than done) but could not explain it as well as you do here. Thank you for the great lesson.

Thanks so much for these videos. Very well done with great explanation and always learn from them. Once again, very much appreciate the time and effort you put into these.

Great lesson!

This video is golden!

This is great advice - have watched it about 3 times now and intend to "try" apply it.

Great video. As you say, many of us apply these rules by intuition, but not with the figures and theory in mind. Well explained. Thank you.

Great explanation. I think I fly that way intuitively but never thought of it that way. As for McCready, while I use it, I don’t think I fly according to it. I fly block STF, the stronger the conditions the higher the speed (but rarely over 100 knots), while speeding up further in sink and slowing down in lift. Shifting gear to lower speeds when lower. I often read discussions on how to determine the MC setting, but don’t often hear how folks who use MC religiously actually follow it in flight. Constantly chasing the speed commands? This requires a lot of attention to the instruments.

Hang gliding life is less complex in this regard: our glide ratio and speed usually is too low to fly by many thermals. Maybe you skip one, or two on a great day, but then you just have to take the third if you even make it that far. Often it is just a matter of deciding when to leave a given thermal to optimize climb ratio, and going to the next one at the right speed, choosing the right path ( or | or ), or follow wherever you see a vulture. Our game involves a lot more direct feel for small bumps in the air within thermals and glide paths, sort of like sailing vs windsurfing I suppose.

Hi Philip, great video, I will try to apply that approach this season. What camera are you using?

Come to NZ! There's only one secretary, her name is Fran, and she's a bit dodg

🎯 Key Takeaways for quick navigation: 00:00 🛩️ La selección de termales es crucial para la velocidad en el vuelo en planeador, y este video ofrece un modelo mental para tomar decisiones informadas. 01:29 🤔 En el vuelo en planeador, aplicar el "problema del secretario" significa que debemos pasar la primera parte de nuestro rango de altitudes recolectando información sobre la fuerza de los termales antes de decidir en cuál detenernos. 03:20 🌄 En la parte inferior de nuestro rango de altitudes, debemos disminuir la velocidad y estar dispuestos a tomar termales más débiles, ya que nuestras opciones se reducen. 05:12 📏 El ajuste de McCready no tiene que ser preciso, pero debe basarse en nuestra estimación de la fuerza del próximo thermal y reducirlo para obtener una velocidad de crucero robusta. 06:12 🔄 El algoritmo para la selección de termales se resume en: evaluar la altura, no detenerse en la parte superior del rango a menos que sea un thermal excepcional, y reducir la velocidad en la parte inferior del rango. Made with HARPA AI

Great rules of thumb! Simple and effective. Thanx for sharing! #makesoaringsexyagain

Nice video! I have a question: which you considera to be the working high band - the whole altitude from ground up to the thermal tops or...from the altitude where the thermals get stronger/ after shear layer/ up to the thermal tops? It is important ,otherwise the maths are different :) Thanks in advance!

Man, is watching your content with great pleasure! Can you give an info in meters both the feets?