Which of the following is NOT a significant event that requires reporting to the Supervisor?

The option indicating unplanned maintenance does not fit the criteria of significant events that require reporting to the Supervisor in the context of radar operations. Typically, significant events that warrant immediate communication to a Supervisor involve situations that impact safety, operational integrity, or the situation on the runways or airspace, such as emergency aircraft, NORDO (No Radio) aircraft, and significant weather occurrences which could affect flight safety.

Emergency aircraft require urgent attention and coordination to maintain safety, while NORDO aircraft pose communication challenges that must be addressed promptly. Significant weather can impact air traffic and necessitates immediate remarking to ensure safe operations. In contrast, unplanned maintenance, while it can be important, is generally considered a routine operational issue that can be managed through standard maintenance workflows rather than needing immediate Supervisor notification.