After landing at a towered airport, when are you considered clear of the active runway?

You are considered clear of the active runway when all of your airplane is across the hold short line before stopping. This is the correct understanding because it ensures that the entire aircraft has completely exited the active runway, thus confirming that it is no longer occupying any portion of the runway's operational area.

This definition is critical in maintaining safety and operational flow at busy towered airports. By requiring all wheels to be beyond the hold short line, air traffic control can clearly assess when an aircraft has vacated the runway, allowing for efficient movement and clearance for other traffic.

In contrast, simply having the wheels leave the runway does not guarantee that the aircraft is clear of the active airspace, as parts of the aircraft could still be within the runway environment. Similarly, passing the hold short line with only a part of the aircraft or stopping before fully crossing the line does not constitute being clear of the runway, as it could still obstruct operations. The definition requires a complete transition beyond the hold short line.