Definition
A required multiengine training maneuver in which the airplane is configured and slowed with one engine simulated inoperative until the pilot recognizes the onset of loss of directional control, and then recovers. It is intended to demonstrate the handling characteristics and warning signs that occur as airspeed approaches Vmc (the minimum control speed with the critical engine inoperative), not to actually reach or fly below that speed.
Plain English
A training exercise where the pilot of a multiengine airplane simulates losing one engine and slows down enough to feel the airplane start to lose directional control, then recovers right at the first sign of trouble. The point is to recognize the warning signs early, not to push the airplane to its limit.
Context Anchor
Seen in multiengine training and in stall or spin-awareness discussions, because a poorly handled VMC demonstration can lead to a loss of control.
Derivation
Vmc stands for 'velocity, minimum control.' 'Demonstration' is used in the FAA training sense -- a maneuver flown to show the pilot can recognize a condition and respond correctly, rather than to fly the airplane to the actual limit.
Why Pilots Care
Helps pilots recognize the airspeed below which an engine failure will cause immediate loss of directional control, reducing the risk of departure from controlled flight.
Grounding Statement
Picture a twin-engine airplane with one side pulling hard and the other side not helping; as speed drops, the rudder has less airflow to keep the airplane straight.
Intuition Check
VMC here does not mean visual weather conditions. In this term, VMC means minimum control speed during a one-engine-out multiengine maneuver.
Example Sentence 1
During the checkride, the examiner asked the pilot to perform a Vmc demonstration to show that he could recognize and recover from an impending loss of directional control.
Example Sentence 2
During the VMC demonstration the pilot recovered by reducing power on the operating engine and lowering the nose to regain directional control.