Plain English Meaning

OEI means one of the airplane's engines is not running. The pilot has to fly, climb, and clear obstacles using only the engine or engines still working.

Full Definition

A flight condition in a multi-engine aircraft in which one engine has failed or has been intentionally shut down, leaving the remaining engine or engines to provide all thrust. OEI performance data, procedures, and obstacle clearance requirements describe how the aircraft must be operated and what climb performance it must achieve when this condition exists, particularly during takeoff and the initial climb.

Context Anchor

Seen in takeoff planning, climb performance, and - requirements .