When is an aircraft considered out of the runway while taxiing?

An aircraft is considered out of the runway while taxiing when the entire aircraft is past the hold short line. The hold short line is specifically designated to ensure that aircraft maintain a safe distance from the runway environment. This line indicates the point where the aircraft must stop or hold before entering the runway or crossing into an area where it could conflict with active runway operations.

The rationale behind this determination is rooted in safety and operational efficiency at airports. The clearance beyond the hold short line indicates that the aircraft is no longer in an active runway area, which is crucial for air traffic control to manage runway traffic and facilitate safe operations. This understanding helps prevent runway incursions, which can lead to dangerous situations.

While the other options present various aspects of runway operations, they do not accurately define when an aircraft is considered out of the runway. For instance, noting the aircraft's nose crossing any threshold or when the landing gear clears the runway does not provide a complete and operationally relevant definition. Similarly, receiving a taxi clearance relates to permission to move but does not pinpoint the specific point of departure from the runway area.