Which of the following is not a reason to file a PIREP?

Filing a Pilot Report (PIREP) is essential for sharing real-time weather observations that can significantly impact flight safety and operations. A PIREP is typically submitted for various reasons, primarily to report significant weather phenomena that could affect other pilots.

Clear weather conditions, while they may seem relevant to report on, are not classified as significant weather events. The primary purpose of a PIREP is to provide information on phenomena that could be hazardous or critical for other flights, such as turbulence, icing, or visibility issues. Therefore, reporting clear weather does not contribute to the critical information dissemination that PIREPs are designed for.

In contrast, unusual occurrences, requests from Air Traffic Control, and situations following a missed approach are all situations where the information provided can aid in maintaining safety and guiding other pilots accurately regarding current conditions. These events can have direct implications for flight safety, making them valid reasons to file a PIREP.