Glide Speed for Range

Glide speed for range is the airspeed at which an unpowered (or engine-out) aircraft achieves the maximum horizontal distance per unit of altitude lost. This corresponds to the best lift-to-drag ratio (L/D_max) and is commonly called “best glide speed” in POH references.

Why Best Glide Speed Matters After Engine Failure

After engine failure, the pilot’s primary goal is to reach a suitable landing area. Best glide speed maximizes the distance available to do so. Flying slower than best glide (increasing AoA beyond L/D_max) increases induced drag and reduces glide distance. Flying faster (decreasing AoA below L/D_max) increases parasite drag and also reduces glide distance.

Effect of Weight

Best glide speed increases with weight. The published best glide speed in the POH is typically for maximum gross weight. At lighter weights, the actual best glide speed is lower. Flying the published speed at light weight is conservative (slightly fast) — not dangerous, but not optimal.

Effect of Wind

In a headwind, increase best glide speed slightly to maximize over-the-ground range. In a tailwind, decrease slightly. The adjustment is modest for typical GA aircraft in typical wind conditions.

Related Terms

See also: Glide Speed for Endurance, Minimum Sink Speed, Aerodynamic Coefficients.