AIM ¶ 7-1-18 — Pilot Weather Reports (PIREPs)
AIM 7-1-18 explains when ATC solicits PIREPs, the standard format, and how pilot weather reports are used by ATC, FSS, ARTCC, and the NWS.
Pilot Weather Reports (PIREPs) are firsthand observations you give to ATC about the weather you're actually flying through. Per AIM 7-1-18, FAA facilities are required to solicit PIREPs when these conditions are reported or forecast:
- Ceilings at or below 5,000 feet
- Visibility at or below 5 miles (surface or aloft)
- Thunderstorms and related phenomena
- Icing of light degree or greater
- Turbulence of moderate degree or greater
- Wind shear
- Reported or forecast volcanic ash clouds
Pilots are urged to volunteer reports on cloud bases/tops/layers, flight visibility, precipitation, visibility restrictions (haze, smoke, dust), winds aloft, and temperature aloft. Make the report to whoever you're talking with — FSS, ARTCC, or terminal ATC. If you can't get one out by radio, call the nearest FSS or Weather Forecast Office after landing.
PIREPs use a standard coded format (TBL 7-1-8). Items 1–6 are always included: station ID, report type (UA/UUA), location (/OV), time (/TM), altitude (/FL), and aircraft type (/TP). Items 7–13 cover sky, weather, temperature, wind, turbulence, icing, and remarks. Don't worry about perfect phraseology — just get the information out so other pilots, ATC, and the NWS can use it for briefings, advisories, and hazardous weather warnings.