Definition
Reports of actual weather conditions encountered by a pilot in flight, transmitted to a ground facility (typically Flight Service) and disseminated to other pilots, controllers, and forecasters. PIREPs include items such as flight conditions, cloud layers, turbulence, icing, visibility, winds aloft, and any unexpected weather. They provide real-time, location-specific weather information that cannot be obtained from forecasts or surface observations alone.
Plain English
A weather report made by a pilot describing what they actually saw or felt while flying — bumps, ice, cloud tops, visibility, and so on — so other pilots and forecasters know what's really happening up there.
Context Anchor
Seen in weather briefings, preflight planning, and en route weather updates, especially before or during instrument flying.
Derivation
Short for Pilot Report. Straightforward — the report comes from the pilot, in the air, about conditions they're experiencing right now.
Why Pilots Care
They provide current, firsthand weather data that forecasts cannot always capture, helping pilots avoid hazards.
Intuition Check
A PIREP is not a forecast. It is a report of conditions a pilot actually encountered in flight.
Example Sentence 1
The briefer mentioned a recent PIREP reporting moderate turbulence at 8,000 feet over the ridge, so we planned to climb above it.
Example Sentence 2
Controllers used the PIREP of severe turbulence to reroute following aircraft.