Definition
An event in which a vehicle, person, or piece of equipment enters any portion of an airport movement area (including runways, taxiways, and associated safety areas) without authorization from air traffic control. It is a reportable surface incident tracked by the FAA as part of runway safety oversight.
Plain English
Someone on the ground — a vehicle, a worker on foot, or a piece of equipment — has gone somewhere on the airport they were not cleared to go. It is treated as a serious safety event because aircraft may be taxiing, landing, or taking off in that same area.
Context Anchor
Seen in airport surface safety, runway incursion reports, tower operations, and airport driving rules.
Derivation
Deviation comes from the Latin deviare, meaning to turn off the path. In this context, the vehicle or pedestrian has 'turned off' from where they were authorized to be and entered a controlled area without permission.
Why Pilots Care
Creates immediate collision risk with aircraft during takeoff or landing and triggers mandatory safety investigations.
Grounding Statement
Picture an airport truck crossing a runway without clearance while an airplane is about to land.
Intuition Check
Do not read “deviation” here as just a small difference or minor mistake. In this term, it means an unauthorized surface movement that can create a serious safety risk.
Example Sentence 1
Tower reported a vehicle/pedestrian deviation when a fuel truck crossed the hold-short line without clearance.
Example Sentence 2
Strict gate procedures help prevent vehicle/pedestrian deviations during busy airport operations.