PIREPS/TAF Codes
(last updated 8/3/2005)
Introduction
Pilot reports (PIREPs) are direct observations of various weather conditions during flight, coded according to established formats and distributed via various channels. Pilots may provide reports to staff at Air Route Traffic Control Centers (ARTCCs), Center Weather Service Units (CWSUs, which are NWS weather support units attached to the ARTCCs), and the Flight Sevice Station (FSS) Flight Watch Desks. U.S. Air Force pilots call their PIREPs into base weather stations (BWS) via the PMSV (Pilot to Metro Service) or through one of the mission radio services. The Air Force BWS then transmit PIREPs over the AWN (Automated Weather Network).
PIREPs are highly useful for establishing where hazardous aviation weather conditions are occurring. However, care must be used when interpreting the information. PIREP data quality can vary based on the aircraft and pilot experience. In addition, PIREP locations are not always completely accurate due to the lag time that often occurs between the observation and making the report.
Civil and commercial PIREPs can also be viewed online at various Websites including the Aviation Digital Data Service (ADDS).
PIREPs appear as UA (upper-air) or UUA (urgent upper-air) reports. Typically, PIREPs contain the location, time, altimeter setting, aircraft type, icing type and/or severity, and additional remarks. They may also contain reports of the sky conditions (which can be valuable in fog and stratus forecasting) weather, temperature, winds, and airspeed. All of these information fields are summarized with code headers, units, and examples in the following table:
| Field | Code(s) | Units | Examples | Example Translations | ||||||||||
| Report Type | UA,UUA | n/a |
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| Location | OV | Nautical miles and degrees magnetic north from a station |
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| Time | TM |
UTC |
/TM 1315 | 1315 UTC | ||||||||||
| Altimeter Setting | FL | 100s of feet, MSL (This is a "pressure altitude" value based on the ground altimeter setting and the altimeter equation) |
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| Aircraft Type | TP | Coded |
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| Sky Conditions | SK |
Usually, overcast cloud deck altitude |
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| Weather | WX | Restrictions to visibility, precipitation | /WX FV02SM ZL- FG SFC-050 | Flight visibility 2 miles in freezing drizzle and fog from the surface up to 5,000 ft | ||||||||||
| Outside Air Temp. | TA | ºC |
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| Wind Speed and Direction | WV | Radial direction and knots | /WV 270022eFL050 | 22 kt from the west at 5,000 ft | ||||||||||
| Indicated Airspeed | IAS | Knots | /IAS 200 | 200 kt | ||||||||||
| Icing Type | IC | Clear, mixed, or rime |
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| Icing Severity | IC | Trace, Light, Moderate, Severe |
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| Remarks | RM | Free form with abbreviations |
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Example:
Coded PIREP:
UA/OV OKC 063064/TM 1522/FL 080/TP CE172/SK 020 BKN 045/060 OVE 070/TA -04/WV 245040/TB LGT/RM IN CLR
Decoded PIREP:
Routine pilot report…64 nm on the 63° radial from Oklahoma City VOR…. At 1522 UTC…. Flight altitude 8,000 ft…. type of aircraft is a Cessna 172… base of broken cloud layer at 2,000 ft with tops at 4,500 ft. base of overcast layer at 6,000 ft with tops at 7,000 ft…outside air temperature is minus four degrees C…wind is from 245° true at 40 kt… light turbulence and clear skies.
Note the following with regard to PIREP codes:
- Useful cloud and weather information is under /SK and /WX respectively
- Miscoding is common
- Not all fields may be reported in any given PIREP
- It can also be very helpful to have lists of airport, navaid, and navigation fix identifiers handy. Airnav.com is an example of a Website that provides free detailed aeronautical information on airports and navigational aids in the U.S.
