Definition
The airspeed that produces the greatest gain in altitude per unit of time for a given airplane configuration and weight. It is the speed at which excess power (power available minus power required) is greatest, allowing the airplane to climb the most feet per minute.
Plain English
The speed that gets you the most altitude per minute. Fly at this speed when you want to climb upward as quickly as possible measured by the clock, not by distance over the ground.
Context Anchor
You will see this term in takeoff and climb procedures, especially when changing from obstacle clearance to a normal climb.
Derivation
The 'y' in Vy is simply a label the FAA and aircraft manufacturers use to tag this particular climb speed, distinguishing it from Vx (best angle of climb). The letters don't stand for words — they're just identifiers.
Why Pilots Care
Using this speed minimizes the time spent climbing, which saves fuel, reduces exposure to traffic and weather, and helps meet ATC altitude restrictions efficiently.
Intuition Check
Do not read “best” as “fastest” or “steepest.” Here, “best” means the speed that gives the most altitude gain in the least time.
Example Sentence 1
After takeoff and once clear of obstacles, the pilot pitched for best rate of climb speed to reach cruise altitude as quickly as possible.
Example Sentence 2
The pilot checked the POH and flew the published best rate of climb speed of 78 knots to minimize time in the climb.