Safe Soaring by Paul Schneider

Decision height:

- Not Just for Instrument Rated Pilots

As glider pilots we make lots of in-flight decisions. This article focuses on decision heights glider pilots should be thinking about and acting on during flight.

The FAA Aeronautic Information Manual (AIM) defines "decision height" as the height at which a decision must be made during an ILS, MLS, or PAR instrument approach to either continue the approach or to execute a missed approach. This definition can be modified and applied to glider flying. Glider flying is all about decision height from lift-off to touch down.

Decision heights for glider Pilots

Takeoff Decision Height

The start of the takeoff roll should stimulate thinking about what-ifs. What if the rope breaks while rolling down the runway? What if a break occurs at 100 feet, 200', 500'.? Glider pilots must be prepared to make the right decision at the right height - whether it is to land straight ahead, execute a 180 and land downwind, or enter a modified pattern and land into the wind.

Release Decision Height

Depending on the mission of the flight, glider pilots need to be thinking about release altitudes. My general rule of thumb when providing glider instruction is to release in the third source of lift. As you know when we are on tow and a thermal is encountered, we can expect to rise shortly after the tow plane rises in front of us. Once, twice, then release during the third up. Depending on your experience level, try releasing during the second lift source. If you don't mind occasionally getting skunked, release just before entering the first lift source. You will know you are there when you see the tow plane rise. Keep safety in mind at all times. Make the right release decision at the right height for your experience level. Check for traffic prior to every release and have enough altitude to make it back to the airfield.

When to exit a thermal decision height

My first glider instructor (yes, it was Dave Robinson from Soar Utah) gave me the best piece of advice I could ever hope to get. He said, "Covet thy lift . it may be all you get today." Seriously, knowing the appropriate decision height for exiting a thermal is a true art and should be studied and practiced. Here are a few "must read" references.

The Art of Thermaling ...Made Easy!

A User-Friendly Guide to Finding and Using Thermals and Thermal Streets
Author: Bob Wander
From Bob Wander's "Gliding ...Made Easy" series


Author: Rolf Hertenstein, Ph.D.
Editor & Publisher: Bob Wander / Soaring Books / USA /

Entering the Pattern Initial Decision Height

Height is your friend; decision-making is your primary task when heading back to the field. As a general rule I use 1500' AGL (7100 MSL) as my decision height when I enter the 36U (Heber City) airport pattern, but this can change depending on conditions, traffic, wind, etc. Most importantly, I make sure I have enough altitude to fly a safe pattern with a variety of traffic.

Final thoughts

Glider pilots should be well aware of decision heights relative to take-off, release, thermals, and landing. Hopefully this information will get us all thinking about these important safety actions. Creating a "Safety Culture" in the glider community is something we can all create. See you on at taxiway Alpha 1.

Thought for the day: Sully Sullenberger (pilot of the US Airways Airbus that made a safe landing in the Hudson River) is a rated glider pilot. He made all the right decisions at the right heights!