Pilot Reports (PIREPs): PHAK Chapter 12

Handbook Reference

PHAK Ch 12

12.pireps. Pilot Reports (PIREPs)

A Pilot Report (PIREP), also called an Aircraft Report (AIREP) in international usage, is a report of actual weather conditions encountered by an aircraft in flight. PIREPs are one of the most valuable tools available to pilots, dispatchers, and forecasters because they provide real-time, in-flight observations of conditions that are otherwise difficult to measure — turbulence, icing, cloud tops and bases, ceilings below an overcast, mountain wave activity, and visibility aloft. Forecasters use PIREPs to refine and validate AIRMETs, SIGMETs, and Center Weather Advisories. Pilots use them to anticipate conditions on their route.

PIREPs are solicited by ATC, Flight Service, and the National Weather Service whenever conditions warrant — particularly when ceilings are at or below 5,000 feet, visibility is at or below 5 statute miles, thunderstorms are reported, icing or turbulence is forecast or reported, or wind shear is suspected. Pilots are encouraged to submit a report any time conditions encountered differ significantly from the forecast.

How to file a PIREP. A pilot may transmit a PIREP to any ATC facility, to Flight Service on 122.0 (Flight Watch was discontinued; EFAS frequencies have been consolidated into Flight Service at 1-800-WX-BRIEF or 122.2 and published RCO frequencies), or via the EFB or ACARS link if available. Controllers transcribe the report and forward it to the Weather Forecast Office, where it is encoded and disseminated nationwide.

PIREP format. The encoded PIREP follows a fixed sequence of elements. Each field is separated by a solidus (/). Required elements are the report type, location, time, flight level, aircraft type, and at least one weather element.

UA — Routine PIREP (Urgent reports use UUA).
/OV — Location, given as a VOR identifier with radial and distance, e.g., /OV BUM 322025 (25 NM on the 322° radial from BUM).
/TM — Time in UTC (4 digits), e.g., /TM 1715.
/FL — Altitude or flight level in hundreds of feet, e.g., /FL085. Use DURC (during climb) or DURD (during descent) when applicable, or UNKN if unknown.
/TP — Aircraft type, e.g., /TP BE36.
/SK — Sky cover. Cloud bases/tops in MSL, e.g., /SK BKN040-TOP080.
/WX — Flight visibility and weather, e.g., /WX FV03SM RA HZ.
/TA — Outside air temperature in Celsius, e.g., /TA M07 (minus 7°C).
/WV — Wind direction (true) and speed in knots, e.g., /WV 24045KT.
/TB — Turbulence (NEG, LGT, MOD, SEV, EXTRM) with type (CAT, CHOP) and altitude band.
/IC — Icing (NEG, TRACE, LGT, MOD, SEV) with type (RIME, CLR, MX).
/RM — Remarks, plain language.

Urgent PIREPs (UUA) are filed for any of the following: tornadoes, funnel clouds, or waterspouts; severe or extreme turbulence; severe icing; hail; low-level wind shear (a loss or gain of airspeed of 10 knots or more near the surface); volcanic ash; or any other phenomenon considered hazardous. These are forwarded immediately to all affected pilots and forecasters.

Example routine PIREP: KMCI UA /OV MCI090015 /TM 1620 /FL060 /TP C172 /SK BKN025-TOP045 /WX FV05SM HZ /TA 12 /WV 18012KT /TB LGT /RM SMOOTH ABV TOPS

Decoded: 15 NM east of Kansas City on the 090° radial, at 1620Z, level 6,000 feet, Cessna 172, broken layer with bases 2,500 ft MSL and tops 4,500 ft MSL, flight visibility 5 SM in haze, OAT +12°C, wind from 180° at 12 knots, light turbulence, smooth above the tops.

Example urgent PIREP: KDEN UUA /OV DEN /TM 2025 /FL110 /TP B737 /TB SEV /RM DURD AT 110

Turbulence intensity definitions (used to encode /TB) are based on aircraft response and occupant reaction:

Light — slight, erratic changes in attitude or altitude.
Moderate — similar to light but greater intensity; occupants feel definite strains against seat belts; loose objects move.
Severe — large, abrupt changes in attitude/altitude; aircraft may be momentarily out of control.
Extreme — aircraft is violently tossed about and practically impossible to control; may cause structural damage.

Icing intensity (used to encode /IC):

Trace — ice becomes perceptible; deicing/anti-icing not utilized unless encountered for over an hour.
Light — occasional use of deice/anti-ice prevents accumulation.
Moderate — even short encounters become potentially hazardous; deice/anti-ice or diversion required.
Severe — deicing/anti-icing fails to control accumulation; immediate diversion necessary.

Pilots should make PIREP submission a habit. A 30-second radio call describing actual conditions aloft contributes directly to the safety of every aircraft that follows.

Oral Exam Questions a DPE Might Ask

Q1What is a PIREP and why are they important?

A PIREP is a Pilot Report of weather conditions actually encountered in flight. They're critical because they provide real-time observations of turbulence, icing, cloud tops, and visibility that forecasters and other pilots can't get any other way, and they're used to update AIRMETs and SIGMETs.

Q2What's the difference between a UA and UUA PIREP, and what triggers an urgent report?

UA is a routine PIREP; UUA is urgent. A UUA is filed for tornadoes or waterspouts, severe or extreme turbulence, severe icing, hail, low-level wind shear of 10 knots or more, volcanic ash, or any other hazardous phenomenon.

Q3How would you file a PIREP in flight?

I'd contact Flight Service on 122.2 or a published RCO frequency, or just give it to the ATC controller I'm working with. I'd report my location relative to a VOR, time, altitude, aircraft type, and the conditions — clouds, visibility, turbulence, icing, temperature, or whatever's relevant.