Definition 1 of 2
Definition
The airspeed that produces the greatest forward distance per unit of altitude lost when an aircraft is gliding without engine power. It corresponds to the angle of attack at which the lift-to-drag ratio is highest, giving the flattest possible glide path through the air.
Plain English
The speed that lets the airplane travel the farthest forward for each foot of height it loses while gliding. Fly faster or slower than this and the airplane will come down sooner.
Context Anchor
Used in engine-out training, emergency procedures, and the aircraft checklist or handbook.
Derivation
Glide comes from an old word meaning to move smoothly or slide. In aviation, it points to the airplane moving forward and downward without engine power. Best means the most favorable speed for distance, not simply the most comfortable or slowest speed.
Why Pilots Care
Maintaining this speed after an engine failure gives the pilot the maximum options for reaching a suitable landing area.
Grounding Statement
Picture the engine going quiet: best glide speed is the target speed that stretches the airplane’s remaining altitude into the most forward travel.
Intuition Check
Best does not mean the airplane stays in the air the longest. Here, best means the airplane covers the greatest distance for the altitude it loses.
Example Sentence 1
When the engine lost power, she immediately pitched for best glide speed and turned toward the nearest airport.
Example Sentence 2
The checklist called for trimming to best glide speed before selecting a landing site.