Vmca is defined as the minimum speed at which directional control can be maintained with one engine inoperative, with the operating engine at take-off power and bank angle limited to how many degrees?

• A. 5°
• B. 15°
• C. 30°
• D. 45°

Answer: (A)

Vmca specifies the minimum speed at which you can maintain directional control with one engine inoperative when the operating engine is at takeoff power, and the bank angle is kept to a very small value. That small limit—five degrees—provides a consistent, conservative condition for measuring rudder authority and yaw stability without the complicating effects of a larger bank, such as increased load factor, greater stall tendency, or altered rudder effectiveness. If the bank were allowed to be larger, the aircraft’s response to asymmetric thrust would change in ways that aren’t standardized, making Vmca less comparable across different airplanes. So the five-degree limit is the reason this definition uses that specific bank angle.