Definition
A condition in a multi-engine airplane in which the thrust produced on one side of the aircraft is unequal to the thrust on the other side, creating a yawing and rolling moment toward the side with less thrust. It most commonly occurs after the failure or partial loss of power in one engine, but can also result from uneven power settings between engines.
Plain English
When one engine produces more push than the other, the airplane wants to twist and turn toward the weaker side. The pilot has to use rudder and aileron to keep the airplane straight.
Context Anchor
Encountered when learning climbs, high-power low-speed flight, and the need for rudder pressure to keep the airplane coordinated.
Derivation
Asymmetric comes from the Greek a- (not) and symmetria (same measure) -- so 'not the same on both sides.' Thrust is the forward force produced by an engine. Together: thrust that is not balanced left-to-right.
Why Pilots Care
The imbalance creates a strong yaw toward the failed engine that must be countered with rudder to keep the airplane under control and climbing.
Analogy
It is like pushing a shopping cart harder on one side of the handle than the other. The cart still moves forward, but it also wants to turn.
Intuition Check
Do not read “asymmetric” as meaning simply “crooked” or “uneven-looking.” Here it means the thrust force itself is not balanced from side to side.
Example Sentence 1
When the right engine lost power during the climb, the pilot countered the asymmetric thrust with firm left rudder.
Example Sentence 2
The training exercise demonstrated how asymmetric thrust grows stronger as airspeed drops and requires prompt corrective action.