What does the term "runway incursion" describe?

The term "runway incursion" specifically refers to an event involving an unauthorized vehicle, person, or aircraft being present on a runway that is active and intended for aircraft operations. This situation poses severe safety risks, as it can lead to potential collisions or accidents involving aircraft taking off or landing. Recognizing and understanding runway incursions is critical for maintaining safe airport operations, as they can disrupt airflow and lead to dangerous scenarios.

Other options provided relate to aviation safety but do not accurately represent what a runway incursion is. A vehicle stopped at an active runway is a specific instance that contributes to a runway incursion but does not encompass the broader definition, which includes all unauthorized entries. The option discussing scheduled inspections pertains to routine safety checks rather than incursion events. Lastly, a pilot's decision to reject a takeoff relates to in-flight safety protocols and decision-making rather than unauthorized presence on the runway.