What constitutes a runway incursion?

A runway incursion is defined as any incorrect presence of an aircraft, vehicle, or person in safety zones that could potentially compromise the safety of flight operations on or near a runway. This includes situations where these entities are in areas where they are not permitted to be, which can lead to collisions or near misses with aircraft that are taking off or landing. The emphasis is on safety and regulation, ensuring that all operations on or around the runway are conducted in a manner that prevents accidents.

The other choices do not align with the definition of a runway incursion. Unscheduled landings represent an operational issue but do not directly relate to the incorrect presence in safety zones. Bad weather, while it can affect runway visibility and operations, does not qualify as a runway incursion. Lastly, unauthorized access to the airport terminal may represent a security issue but does not pertain to runway safety zones or the definition of incursions.