When are vehicles or equipment allowed to operate close to an active runway?

Vehicles or equipment are allowed to operate close to an active runway when they have received necessary authorization through direct communication with the control tower. This ensures that the movement of vehicles does not interfere with aircraft operations, maintaining safety for both airborne and ground traffic.

The requirement for direct communication means that vehicle operators must follow established protocols to confirm their presence and intended movements in the area, which helps prevent accidents and enhances situational awareness for air traffic controllers. This option emphasizes the importance of communication and coordination in maintaining a safe airspace environment.

In scenarios where communication with the control tower is not established or if there is no specific authorization, the risk of collision increases significantly, which is why the other options do not encapsulate the safety protocols necessary for runway operations.