Definition
VMC is the minimum airspeed at which a multi-engine airplane can be controlled in flight after the sudden failure of the critical engine, with the remaining engine at takeoff power. Below this speed, the rudder no longer has enough authority to counteract the asymmetric thrust produced by the operating engine, and the airplane will yaw and roll uncontrollably toward the dead engine. VMC is determined by the manufacturer under specific test conditions defined in the certification regulations and is marked on the airspeed indicator with a red radial line.
Plain English
On a twin-engine airplane, VMC is the slowest speed at which you can still keep the plane flying straight if one engine quits. Go slower than this with one engine out and full power on the other, and the airplane will swing and roll out of control no matter how hard you push the rudder.
Context Anchor
Seen in multi-engine training, airspeed markings, performance discussions, and engine-failure planning.
Derivation
V stands for velocity and MC for minimum control. The 'C' is sometimes shown as a small subscript (VMC). The naming convention comes from a standard FAA/ICAO system where 'V-speeds' are critical airspeeds the pilot must know.
Why Pilots Care
Operating below this speed after an engine failure usually results in an immediate loss of directional control and possible roll into the dead engine.
Grounding Statement
At or above VMC, the airplane has enough control authority to resist the turning force from one engine making power and the other not making power.
Intuition Check
This VMC does not mean visual meteorological conditions. It also does not mean the airplane will climb on one engine; it only means the airplane can still be controlled directionally under the specified conditions.
Example Sentence 1
After the right engine failed on climb-out, the pilot immediately lowered the nose to keep the airspeed safely above VMC.
Example Sentence 2
The pilot rotated at a speed above VMC so that an engine failure immediately after liftoff would not cause loss of control.