Definition
The horizontal distance an aircraft requires to take off and reach a specified screen height above the runway surface when one engine has failed at or after the critical decision speed during the takeoff roll. For multi-engine aircraft operated under performance rules, this distance accounts for the reduced thrust available after the engine failure and is used to determine whether the runway is long enough to legally and safely depart.
Plain English
The runway length needed to get airborne and clear a set height above the ground after losing one engine during the takeoff. Because the aircraft accelerates more slowly on the remaining engine, this distance is longer than a normal all-engines takeoff distance.
Context Anchor
Seen in multi-engine IFR departure planning, especially when checking whether a departure can clear obstacles after an engine failure on takeoff.
Derivation
OEI stands for One Engine Inoperative. The phrase combines that condition with 'takeoff distance,' meaning the distance required to complete the takeoff under that specific failure condition rather than under normal operations.
Why Pilots Care
Determines whether the runway and departure path allow a safe climb-out if an engine fails at the worst possible moment during takeoff.
Grounding Statement
Picture the airplane starting down the runway, losing one engine during the takeoff, and still needing enough remaining distance to lift off and reach the required height.
Intuition Check
Do not read this as normal takeoff distance with all engines working. OEI takeoff distance is the takeoff distance for the continued-takeoff case after one engine has failed.
Example Sentence 1
Before departure, the crew checked that the available runway exceeded the OEI takeoff distance for their current weight and temperature.
Example Sentence 2
Obstacle clearance charts list the OEI takeoff distance so crews can verify they will clear terrain even on a single-engine climb.