Definition
The slowest airspeed at which a multi-engine airplane can be controlled directionally with the critical engine suddenly inoperative, the remaining engine at takeoff power, and the airplane configured per the manufacturer's certification conditions. Below this speed, the rudder and ailerons can no longer counteract the yawing and rolling forces produced by asymmetric thrust, and the pilot loses directional control.
Plain English
The lowest speed at which a twin-engine airplane can still be flown straight if one engine quits. Slower than this, the working engine pushes the airplane sideways more strongly than the rudder can correct, and the pilot can no longer keep it pointed where it's going.
Context Anchor
Seen in multiengine training, engine-failure discussions, takeoff planning, and aircraft performance information.
Derivation
Minimum' comes from Latin minimus, meaning 'least'. The term is literal: it is the least amount of speed at which control is still possible after an engine failure. The word 'control' here specifically means directional control -- keeping the nose pointed where you want it -- not control of altitude or airspeed.
Why Pilots Care
It sets the safe lower limit for continued flight after an engine failure so the pilot does not lose directional control.
Grounding Statement
As airspeed decreases, less air flows over the control surfaces, so the controls become less effective.
Intuition Check
Minimum control speed does not mean the slowest safe flying speed, and it does not mean stall speed. It means the lowest speed where the airplane can still be controlled in the specific condition being discussed.
Example Sentence 1
During the engine-out demonstration, the instructor reduced power on the left engine and had the student maintain heading until reaching minimum control speed.
Example Sentence 2
The instructor had the student identify minimum control speed during the engine-out demonstration.