Definition
VY is the airspeed that produces the greatest gain in altitude per unit of time. At VY, the difference between the power available from the engine and the power required to maintain level flight is at its maximum, so the airplane climbs to a given altitude in the shortest time.
Plain English
VY is the speed that gets you up to a chosen altitude in the least amount of time. Fly at VY when you want to gain height as quickly as possible measured by the clock.
Context Anchor
You will see VY in climb procedures, performance charts, and pilot operating handbook guidance for normal climbs after takeoff.
Derivation
The 'V' comes from the Latin velocitas, meaning speed — used throughout aviation as the symbol for a defined airspeed. The subscript 'Y' is simply an FAA designator that pairs with 'X' (best angle of climb) to label the two main climb speeds.
Why Pilots Care
Flying at VY gets the airplane to a safe or required altitude in the shortest possible time, which matters for obstacle clearance, traffic pattern entry, and overall trip efficiency.
Intuition Check
Best rate does not mean the steepest climb path over the ground. It means the most altitude gained in a given amount of time.
Example Sentence 1
After lift-off and once clear of any obstacles, the pilot pitched for VY to climb to cruise altitude as quickly as possible.
Example Sentence 2
With a high density altitude, the pilot referenced the performance chart to confirm the correct VY for the current weight.