Which of the following is an acceptable reason to enter an active taxiway?

Entering an active taxiway requires careful consideration of safety protocols, as these areas are critical for the movement of aircraft. The only acceptable reason for an airside vehicle to enter an active taxiway is when clearance has been explicitly granted by Air Traffic Control (ATC). This process ensures that the vehicle's movement is coordinated with the operations of aircraft in the vicinity, preventing potential accidents or disruptions.

Receiving specific authorization from ATC means that the controller is aware of the vehicle's presence and can provide necessary traffic advisories or instructions to pilots in the area. This communication is vital for maintaining safety on the airfield.

The other reasons for entering an active taxiway lack safety measures. While emergencies may sometimes necessitate urgent action, the entry into taxiways must still be coordinated with ATC. Simply wanting to avoid traffic does not align with safety protocols, and the absence of visible aircraft does not guarantee safety, as there could be hidden dangers or aircraft on approach that are not immediately visible. Thus, the only scenario that adheres to established safety guidelines is obtaining clearance from ATC.