What backup action should a pilot take if radar contact is lost?

When a pilot loses radar contact, the most appropriate backup action is to advise Air Traffic Control (ATC) and follow established procedures. This is critical because maintaining communication with ATC is essential for ensuring safety and coordination in airspace.

When radar contact is lost, the pilot should report the situation to ATC promptly. This keeps ATC informed about the aircraft's status and allows them to provide assistance in reestablishing contact, as well as coordinating with other traffic in the area. Following established procedures is vital because they are designed to promote safety and effective management of the aircraft’s flight path, which includes protocols for handling situations where communications are disrupted.

In contrast, continuing to fly the route as planned without guidance from ATC could lead to potentially hazardous situations, especially if there are other aircraft nearby or if there is a change in weather conditions. Starting a descent without clearance may violate safety protocols, as pilots must have ATC approval for such actions to maintain safe vertical separation between aircraft. Directly contacting maintenance support is not relevant in this scenario because maintenance procedures do not address real-time navigation and air traffic management issues that arise from losing radar contact.