If an airport operates on a part-time basis, what will be indicated in place of forecast text when the airport is closed?

When an airport operates on a part-time basis and is closed during a portion of the forecast period, the appropriate indication in place of the forecast text is "NIL." This term specifically signifies that there are no forecast conditions for that particular time frame, meaning that there will be no aviation activities due to the airport being closed.

The use of "NIL" is well-established in aviation communication, particularly in METAR and TAF reports, as it provides clear information that no forecast is applicable at that moment. This prevents misunderstandings among pilots and air traffic controllers regarding the usable status of the airport.

While other terms may seem plausible, they do not convey the same established meaning in aviation contexts. "OFF," "CLOSED," or "STOP" do not have standardized meanings in TAF reporting. In fact, they could create ambiguity or confusion rather than the clarity that "NIL" provides, underscoring the importance of using correct and recognized terminology within aviation.