Definition
An event in which an aircraft on the runway surface departs the runway during takeoff or landing. The departure may be off the side of the runway (a veer-off) or off the end of the runway (an overrun).
Plain English
When an aircraft accidentally leaves the runway during takeoff or landing — either by sliding off the side or running off the far end.
Context Anchor
Seen in landing, takeoff, rejected takeoff, runway safety, and accident-prevention discussions.
Derivation
Excursion comes from the Latin excurrere, meaning 'to run out' (ex- 'out' + currere 'to run'). In everyday speech an excursion is a pleasant trip, but the original sense — running outside of where you're supposed to be — is exactly what's meant here: the aircraft has run out beyond the boundaries of the runway.
Why Pilots Care
Runway excursions are among the most common runway accidents and can cause aircraft damage, injuries, or loss of life if procedures for speed, braking, and surface conditions are not followed.
Grounding Statement
Picture an aircraft landing and continuing beyond the pavement, or drifting sideways off the runway edge before it can be stopped.
Intuition Check
A runway excursion is not a planned trip or route change. In aviation, it means the aircraft unintentionally left the runway surface.
Example Sentence 1
The pilot landed long on a wet runway and a runway excursion occurred when the aircraft overran the end of the pavement.
Example Sentence 2
Crosswind landings increase the risk of a runway excursion if directional control is lost.