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What is a PIREP?

PIREPs, also know as pilot reports are one of the most forgotten basic weather observations around.

Pilots are one of the best sources and can provide the only real time source of upper altitude weather observations during flight.

Decoding a PIREP

All PIREP require current data as follows:

  • UA – Routine, UUA – Urgent

  • /OV – location of the PIREP, using a 3-letter NAVAID identifier (/OV LGB – over Long Beach VOR)

  • /TM – Time the PIREP was received from the pilot

  • /FL – Flight Level or altitude during the report in hundreds of feet.

  • /TP – Type aircraft, using a 4-digit identifier (C172, PA28, B737, A320, UNKN = Unknown)

Optional Information on a PIREP report:

  • /SK – Cloud cover: are in MSL (measured sea level)

    • Height of cloud base

    • Height of cloud tops

    • Separate cloud layers use (/) – SK 005 BKN / SK 012 OVC

    • UNKN –unknown

  • /WX - Weather or flight visibility

  • /TA – Air temperature in Celsius (TA15 (15⁰C), TA -06 (minus 6⁰C))

  • /WV – Wind direction and velocity, in a six digit format – WV 280110

  • /TB – Turbulence

  • /IC – Icing - /IC LGT RIME (icing light rime ice)

  • /RM – Remarks



This PIREP is a Routine (UA) Upper Air observation. The aircraft that is reporting this PIREP is over the BYP VOR station, northeast of DFW international airport (OV BYP) at 1339 Zulu. The aircraft was flying at an altitude of 16,500 feet (FL165) and the aircraft type is a Lear Jet 40 (TP LJ40). Addition information about the pilots’ observation is in the remarks section, which says; moderate turbulence with drifting dust (DURD), accelerated with wind shift. This aircraft is a “SKYSPOTTER” (AWC-WEB).

Learning to read PIREPs can be difficult, but pilots must learn it.

Remember, giving a PIREP to Flight Service is much appreciated and they are more than happy to talk.


An AIREP (Air Report) is an automated report of the current in-flight weather conditions, generated by the onboard computer systems. Whereas, a PIREP is a report given by a pilot visually, both are transmitted in real-time via the radio to ground stations. The information in an AIREP is the same as a PIREP, except that an AIREP uses latitude and longitude for location, unlike a PIREP which is based on location by a NAVAID or VOR station. AIREP’s are more common over the ocean where there are no weather forecasting or observation stations.

Decoding an AIREP:

ARP ASA889 3500N 14221W 1900 F340 M54 172/013

  • ARP – Is the abbreviation for AIREP

  • ASA889 – Is the flight number that gave the AIREP, Alaska Airlines 889

  • 3500N – 35⁰00’ North latitude

  • 14221W – 142⁰21’ West longitude

  • 1900 – The time the report was given

  • F340 – Flight level 340 or 34,000 feet

  • M54 – the temperature is minus 54⁰C

  • 172/013 – the wind direction and speed, 172 at 13kts


The weather for the day is scattered at 3,500 feet AGL with 10SM visibility. You are flying at 1,300 feet MSL in VFR Meteorological Conditions (VMC). You notice that the leading edges of the wings are beginning to accumulate icing. What are some options?

First, find a place to land as soon as possible, the airplane is not equipped with deicing or anti-icing equipment.

Secondly, call in a PIREP to ATC or the nearest Flight Service Station which will alert them along with other pilots flying in the area of the changing conditions.

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