Definition
A report of actual weather conditions encountered by an aircraft in flight, transmitted by the pilot to a ground facility (such as Flight Service or ATC) for distribution to other pilots and weather services. A Pirep typically includes location, time, altitude, sky conditions, visibility, temperature, wind, turbulence, icing, and any other significant weather observed.
Plain English
A short weather report a pilot makes from the air, describing what the weather is actually doing where they are flying, so other pilots and forecasters know what to expect.
Context Anchor
Pilots encounter Pireps during preflight weather planning, while talking with air traffic control or flight service, and when sharing conditions they find in flight.
Derivation
Short for 'Pilot Report.' The compressed form is used because reports are passed quickly over radio and in text weather products where brevity matters.
Why Pilots Care
Supplies real-time weather details that forecasts may miss, helping pilots avoid turbulence, icing, or low visibility.
Intuition Check
A Pirep is not a forecast. It is a report of what a pilot actually encountered.
Example Sentence 1
Approaching the front, the pilot filed a Pirep reporting moderate turbulence and light rime icing at 8,000 feet.
Example Sentence 2
I checked the latest Pireps before takeoff to see if turbulence had been reported along my route.