At what speed should one climb with one engine inoperative?

Climbing with one engine inoperative is a critical phase in aviation, particularly in multi-engine aircraft operations. The appropriate speed for this situation is known as V2, which is the minimum safe takeoff climb speed. This speed ensures that the aircraft can safely clear obstacles and maintain positive control after an engine failure during the climb phase.

V2 is specifically defined in relation to the aircraft's performance characteristics and is engineered to provide the necessary climb rate and control margin when one engine is not functioning. Flying at V2 allows the pilot to achieve a safe altitude, even in the face of the additional drag and reduced thrust that results from the loss of an engine.

In contrast, V1 is the critical decision speed beyond which the pilot must continue the takeoff even if an engine fails, but it does not provide the same margin for climb performance as V2. V3, which might refer to another performance speed used in some contexts, does not generally apply to engine failure scenarios, and Vf, if interpreted as the final approach speed, is not relevant during the initial climb after an engine failure. Thus, V2 is the correct choice for ensuring safety and control during a climb with one engine inoperative.