Which speed offers maximum obstacle clearance during a climb?

The speed that offers maximum obstacle clearance during a climb is the speed of greatest excess thrust available over required thrust. This speed ensures that the aircraft can achieve the necessary performance to clear obstacles effectively while maintaining a positive climb rate. When an aircraft is climbing after takeoff, it must reach a speed that allows it not only to ascend but also to have sufficient thrust margin to handle any unexpected situations, such as wind shear or an engine failure.

This speed is critical, particularly in the early stages of flight when the aircraft is climbing away from the runway and navigating around obstacles. It strikes a balance between these factors, enabling the aircraft to maximize its climb performance and maintain safety margins effectively.

The other speeds mentioned, such as V2 (the takeoff safety speed) or the speed for maximum climb angle (VX), play important roles in climb performance but do not specifically provide the same maximum obstacle clearance efficiency as the speed of greatest excess thrust. V2 is primarily focused on providing a safety speed in the event of an engine failure, while VX emphasizes the angle of climb rather than obstacle clearance performance under varying conditions. The speed for maximum rate of climb might optimize altitude gain over time but does not necessarily account for obstacle clearance.