Which term describes Vy?

Vy, or the best rate of climb speed, is the airspeed that allows an aircraft to gain the most altitude in the least amount of time. It is a critical concept for pilots, as achieving this speed during a climb maximizes the performance of the aircraft. At this speed, the aircraft's excess thrust is optimized to ensure that it is climbing as efficiently as possible, which is particularly important in scenarios such as an engine failure or during takeoff where altitude gain is crucial.

The best rate of climb speed is especially relevant during initial climb after takeoff, allowing pilots to achieve a safe altitude quickly, which can be vital in avoiding obstacles or in emergencies. Understanding Vy helps pilots make informed decisions about when to climb and at what speed for safety and performance efficacy.