Definition
An informal term referring to one of two specific airspeeds published in the airplane's flight manual that produce the most efficient climb performance: V_Y, the speed for the greatest gain in altitude per unit of time, or V_X, the speed for the greatest gain in altitude per unit of horizontal distance traveled. The correct speed depends on the pilot's objective during the climb.
Plain English
The airspeed that gives the best climb for what the pilot is trying to achieve — either climbing the most altitude in the shortest time, or climbing the most altitude over the shortest distance across the ground.
Context Anchor
Used during takeoff and climb planning, especially when following the airplane’s handbook speeds after liftoff.
Why Pilots Care
Flying at this speed ensures the airplane clears obstacles safely and reaches a safe altitude in the shortest time or distance, directly affecting departure safety and fuel efficiency.
Intuition Check
“Best” does not mean one speed is best for every climb. Here it means best for a stated climb goal, such as climbing over distance or climbing over time.
Example Sentence 1
After lift-off with trees off the end of the runway, the pilot pitched for the best angle of climb speed until the obstacle was cleared, then accelerated to the best rate of climb speed.
Example Sentence 2
Once clear of obstacles the pilot accelerated from best climb speed to cruise climb speed for better engine cooling and forward visibility.