Definition
The airspeed that produces the greatest forward distance per unit of altitude lost when the airplane is gliding without engine power. It represents the lift-to-drag ratio at its most efficient point for the airplane's current weight and configuration, and is published in the Pilot's Operating Handbook for the manufacturer's tested weight.
Plain English
The specific airspeed that gives you the longest possible glide for the height you have available. Fly faster or slower than this speed and you will not travel as far through the air before reaching the ground.
Context Anchor
Used during power-off approaches, engine-out practice, and any situation where the pilot needs to manage how far the airplane can glide without added power.
Derivation
“Glide” comes from an old word meaning to move smoothly. In aviation, it means the airplane is descending through the air without relying on engine power to stay up. “Best” means best for distance here, not best in every possible way.
Why Pilots Care
It determines how far the aircraft can reach a suitable landing site after an engine failure.
Intuition Check
Best glide does not mean the slowest glide, the longest time in the air, or the softest descent. It means the airspeed that gives the most forward distance for the altitude being lost.
Example Sentence 1
After the engine quit, the pilot pitched for best glide and turned toward the nearest airport.
Example Sentence 2
The pilot referenced the POH to confirm best glide speed for the current weight before beginning the power-off approach.