What does the term "runway incursion" refer to?

The term "runway incursion" specifically refers to an unauthorized presence in a runway's protected area. This concept is crucial to airport safety, as runway incursions can lead to serious accidents involving aircraft, vehicles, or personnel. Such incidents occur when an aircraft, vehicle, or person is on the runway without permission during takeoff or landing operations, potentially causing hazardous situations. The definition emphasizes the critical need for maintaining clear and controlled access to runways to ensure safe aircraft movements. Understanding this definition helps aviation personnel recognize the importance of following proper procedures and maintaining vigilance around runways.