What must be done if the outer marker signal is not received during an approach?

When the outer marker signal is not received during an approach, it is crucial to inform Air Traffic Control (ATC) and begin a missed approach. The outer marker typically indicates an important position in the approach procedure, especially in instrument approaches. Its absence can signal a potential issue with the approach, such as navigational errors or signal failures.

Not receiving the outer marker means the aircraft may not be properly aligned for landing or may not accurately gauge its distance from the runway, increasing the risk of an unsafe landing. Therefore, pilots are trained to execute a missed approach in such situations to ensure safety. This action involves climbing to a safe altitude and following specified procedures to either circle back for another attempt or divert to an alternate airport, if necessary.

Continuing the approach as planned without confirming the outer marker signal can lead to dangerous situations, such as landing without proper guidance. Checking navigational equipment for failure can be part of the process but is secondary to ensuring safety by aborting the landing attempt. Terminating the flight and diverting to an alternate might be a consideration if conditions warrant, but the immediate response in the absence of the outer marker is to initiate the missed approach procedure and notify ATC for further guidance.