Definition
In a multiengine airplane, the minimum speed at which the pilot can safely maintain directional control and a positive rate of climb following the failure of one engine, with the remaining engine at takeoff power and the airplane in the appropriate configuration. It is the speed below which an engine failure may make safe continued flight impossible, and is typically established by the manufacturer above the airplane's minimum control speed (VMC).
Plain English
The slowest speed at which a twin-engine airplane can keep flying safely, and climb, if one engine quits. Below this speed, losing an engine becomes very dangerous because the pilot may not be able to control the airplane or stay in the air.
Context Anchor
Used in multiengine training when practicing engine failures, engine shutdowns, or one-engine-inoperative procedures.
Why Pilots Care
It creates a safety buffer that prevents loss of directional control if the student or instructor must demonstrate or practice an engine-out situation.
Intuition Check
“Safe” does not mean risk-free. Here it means the minimum approved or recommended speed for intentionally practicing with one engine not producing power. “Single-engine” does not mean a single-engine airplane. It means a multiengine airplane being flown with only one engine producing useful power.
Example Sentence 1
The instructor reminded the student that until the airplane reaches safe single-engine speed, an engine failure on takeoff will likely require landing straight ahead rather than continuing the climb.
Example Sentence 2
Maintaining safe single-engine speed after the simulated failure allowed the student to keep the airplane under control and establish a climb.