What is the critical engine-out minimum control speed, commonly referred to as Vmc?

The critical engine-out minimum control speed, known as Vmc, is defined as the minimum airspeed at which a multi-engine aircraft can maintain controlled flight with one engine inoperative. When an engine fails, the aircraft experiences a yawing moment towards the inoperative engine due to the asymmetrical thrust. Vmc is critical because if the aircraft drops below this speed while attempting to maintain control after an engine failure, it can lead to a loss of control and possible spin.

Understanding Vmc is essential for multi-engine pilots since it dictates safe operating limits during an engine-out scenario. It's vital to recognize that this speed is not about maintaining level flight or optimizing fuel efficiency but rather ensuring that the pilot has sufficient control authority to counteract the yaw and maintain flight stability when one engine is not producing thrust.

The other options do not accurately describe Vmc; for example, it is not a speed for stall recovery because that is related to different aerodynamic factors, nor is it about the speed for optimum fuel efficiency, which focuses on different operational parameters.