When is it unnecessary to inform an aircraft that radar service is terminated?

Informing an aircraft that radar service is terminated is a standard procedure, but there are specific scenarios when it may not be necessary. In the context of the correct answer, when an aircraft switches to a different frequency after landing, it generally indicates that the pilot is transitioning to another form of communication, typically with a ground control or other services. This action implies that the pilot is aware they are no longer on the radar service due to their change of operational status.

In this scenario, the aircraft is effectively concluding its radar service on its own accord by transitioning to a different communication frequency, which usually occurs after landing and aligns with standard operating procedures. Thus, formally notifying them of radar service termination is redundant because their action already signifies this change.

The other scenarios involve situations where clear communication about radar service is essential to ensure safety and proper operation. For instance, a VFR aircraft cleared for landing still needs to be reminded that radar service has ended to avoid any potential miscommunication. Similarly, an IFR flight plan cancellation in uncontrolled airspace necessitates a termination notification to clarify that the aircraft is no longer under air traffic control. Lastly, in the case of multiple aircraft operating in the same airspace, maintaining awareness of radar service status among all parties is crucial