What must be done if an aircraft's ADS-B Out system fails?

If an aircraft's ADS-B Out system fails, requesting a deviation for operations in affected airspace is the appropriate course of action. This system is crucial for transmitting the aircraft's position, velocity, and intent to air traffic control and other aircraft, particularly in controlled airspace.

When the ADS-B Out system is not functioning, the aircraft may no longer be able to communicate its location effectively with ATC, which violates regulations that require the ADS-B Out capability in certain airspaces. By requesting a deviation, the pilot seeks permission to continue operating in the affected airspace while acknowledging the failure and ensuring that all necessary precautions are taken for safe navigation.

In contrast, taking no action could lead to regulatory non-compliance, while filing a flight plan without ADS-B Out could also lead to similar issues. Landing immediately might be unnecessary, depending on the situation, especially if the pilot can safely navigate in alternative ways. Thus, requesting a deviation helps maintain safety and compliance with aviation regulations.