Definition
A condition in a multiengine airplane in which one engine has failed or been intentionally shut down while the remaining engine or engines continue to provide thrust. OEI is used to describe performance, handling, and procedures that apply specifically when a multiengine airplane is operating without all engines producing power.
Plain English
One of the airplane's engines has stopped working, and the airplane is flying on the engine or engines that are still running.
Context Anchor
Seen in multiengine airplane training, performance charts, emergency procedures, and discussions of engine failure after takeoff.
Why Pilots Care
It reduces climb performance and thrust, making obstacle clearance and control more demanding, especially right after takeoff.
Intuition Check
OEI does not always mean the engine is physically destroyed. It means that, for the situation being discussed, one engine is not producing usable power for flight.
Example Sentence 1
After the right engine failed during climb, the crew followed the OEI procedure and continued to a safe landing on the remaining engine.
Example Sentence 2
The pilot checked the OEI climb gradient to confirm the aircraft could clear terrain on the remaining engine.