Definition
The airspeed, designated Vx, that produces the greatest gain in altitude over the shortest horizontal distance after takeoff. It is flown when terrain or obstacles must be cleared shortly after liftoff, and it is slower than the best rate-of-climb speed (Vy).
Plain English
The speed that gets you the most height in the least ground covered. You use it when something tall is in front of you and you need to climb steeply to clear it.
Context Anchor
Seen in takeoff performance information, obstacle-clearance procedures, and the climb section of an airplane’s flight manual or pilot’s operating handbook.
Derivation
The 'angle' here refers to the climb angle measured against the ground — a steeper angle means more height gained per unit of distance traveled forward. 'Best' means the speed that maximizes this angle for a given aircraft and configuration.
Why Pilots Care
Allows safe clearance of obstacles close to the runway end when runway length is limited.
Grounding Statement
Use best angle-of-climb airspeed when the main problem is not time, but distance: you need to gain height before reaching something ahead.
Intuition Check
Do not read “best climb” as “fastest climb upward per minute.” Best angle-of-climb airspeed is about gaining the most height over the shortest ground distance.
Example Sentence 1
After liftoff from the short strip with trees at the departure end, the pilot held best angle-of-climb airspeed until the obstacles were cleared, then accelerated to a normal climb speed.
Example Sentence 2
With a power line just beyond the departure end, the checklist called for best angle-of-climb airspeed until the obstacle was cleared.