1) Any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle or person on the protected area of a surface designated for the landing and take-off of aircraft.
2) Any unauthorised presence on a runway of aircraft, vehicle, person or object where an avoiding action was required to prevent a collision with an aircraft.
1) ICAO (2005) ICAO Document 4444 "Air Traffic Management - Procedures for Air Navigation Services", page 1-10
2) EUROCONTROL (2009) ESARR 2 Reporting and Assessment of Safety Occurences in ATM
FAA adopted the ICAO definition of "runway incursion" in 2007: FAA order 8020.11C