Which statement about Vy is correct?

• A. Vy is the best rate of climb (maximum altitude per unit time).
• B. Vy is the best angle of climb.
• C. Vy is the stall speed.
• D. Vy is the maximum glide speed.

Answer: (C)

Vy is the airspeed that gives the greatest rate of climb—the fastest increase in altitude per unit time once the airplane is climbing in its current configuration. This speed is chosen to maximize vertical speed, taking into account weight, power, altitude, and aerodynamic setup. It’s not the speed at which the aircraft stalls; stall speed (Vs) is the minimum steady flight speed for a given configuration, and Vy sits well above that value.

Understanding the other climb speeds helps: Vx is the best angle of climb, which maximizes altitude gained per horizontal distance and is useful for obstacle clearance at the start of the climb. The maximum glide speed is the speed to use in a power-off glide to cover the greatest distance, not a climb performance speed. So Vy specifically describes the best rate of climb, not stall speed.