A pilot report or PIREP is a report of actual flight or ground conditions encountered by an

aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines. ...

. Reports commonly include information about atmospheric conditions (like

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on ...

, icing, turbulence) or airport conditions (like

runway condition code Runway safety is concerned with reducing harm that could occur on an aircraft runway. Safety means avoiding incorrect presence (incursion) of aircraft, inappropriate exits (excursion) and use of the wrong runway due to confusion. The runway conditi ...

s or ground equipment failures). This information is usually relayed by

radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transm ...

to the nearest ground station, but other options (e.g. electronic submission) also exist in some regions. The message would then be encoded and relayed to other weather offices and air traffic service units. Although the actual form used to record the PIREP may differ from one country to another, the standards and criteria will remain almost the same. At a minimum the PIREP must contain a header, aircraft location, time, flight level, aircraft type and one other field. In recent years, a PIREP will also include UA or UUA used to identify the PIREP as routine or urgent.

Included data

Mandatory

*UA or UUA used to identify the PIREP as routine or urgent (In Canada this is indicated by the prefix to the PIREP: "UACN01" for an urgent PIREP or "UACN10" for a normal PIREP) */OV location of the PIREP, in relation to a NAVAID, an aerodrome or geographical coordinates */TM time the PIREP was received from the pilot ( UTC) */FL flight level or

altitude Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...

above

sea level Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardise ...

at the time the PIREP is filed; it is essential for turbulence and icing reports */TP aircraft type; it is essential for turbulence and icing reports

Optional (at least one is required)

*/SK

sky cover In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may compo ...

*/TA ambient temperature; important for icing reports */WV wind vector referenced in terms of true north (ICAO), or magnetic north (in the United States) */TB turbulence; intensity, whether it occurred in or near clouds, and duration */IC icing */RM remarks */WX flight visibility and weather

AIREP

Like PIREPs, Aircraft Reports (AIREP) are reports of actual weather conditions of an aircraft in flight. AIREPs are often automated reports, contrary to PIREPs. Likewise, a different

encoding In communications and information processing, code is a system of rules to convert information—such as a letter (alphabet), letter, word, sound, image, or gesture—into another form, sometimes data compression, shortened or secrecy, secret ...

is used for either type.

Body

The message identifier "UA" is used when the PIREP contains non-hazardous weather information. If the PIREP contains a report of a tornado, funnel cloud, waterspout, severe turbulence, severe icing, hail, or a low-level

wind shear Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizon ...

hazard, the identifier "UUA" would be used. The location (/OV) can be reported in one of three ways: as a direction and distance from a navigation aid (NAVAID), as a direction and distance from an airport, or as the

latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north po ...

and

longitude Longitude (, ) is a geographic coordinate that specifies the east– west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek let ...

of the aircraft. The time (/TM) used is the UTC time that the PIREP is reported. The flight level (/FL) is reported as either a three digit value that indicates the altitude of the aircraft above sea level in hundreds of feet or can be one of three abbreviations: DURD (during descent or on approach), DURC (during climb or after takeoff) and UNKN (unknown). Aircraft type (/TP) will be the approved ICAO designator, or UNKN if not reported. Sky cover (/SK) is used to report the cloud layer amounts and the height of the cloud base. The tops of the cloud layers can also be included, as can more than one layer of cloud. Heights are in hundreds of feet above sea level and are three digits. Abbreviations used in this group are "CLR" (clear), "FEW" (few), "SCT" (scattered), "BKN" (broken) and "OVC" (overcast). Temperature (/TA) is the air temperature in whole degrees Celsius as a two-digit value, with negative temperatures preceded by a minus (-) sign. In the United States, negative temperatures are preceded by the letter M (M). Wind velocity (/WV) must contain both the wind speed and direction. Direction is reported as a three-digit value in whole degrees true and the wind speed in knots also in three digits. Turbulence (/TB) and the intensity are reported in a PIREP based on the aircraft and occupants reaction to the turbulence. The altitude of the turbulence should be included using three-digit groups. When the top or the base of the turbulence is unknown then the abbreviation BLO (below) or ABV (above) should be used. Turbulence should be reported as LGT (light), MDT (moderate), SVR (severe) or in exceptional cases EXTRM (extreme). Clear-air turbulence is reported as CAT. Icing (/IC) is reported by type and the intensity or rate of accretion. The type of ice is reported as "CLR" (clear), " RIME", or "MXD" (mixed). The intensity is reported as "TR" (trace), "LGT" (light), "MDT" (moderate), and "SVR" (severe). (Units are measured in MSL - MEAN SEA LEVEL) Remarks (/RM) report on other weather conditions that are not covered in the rest of the PIREP may include such things as icing in precipitation, thunderstorms, St. Elmo's fire and frontal conditions. There are many other types of weather conditions that could be reported in a PIREP. The above explanation of PIREP fields is Canadian. The United States version may also include a weather (/WX) group, while other countries may use other groups and measurements.

Examples of PIREPs

These examples are taken from the Canadian MANOBS (Manual of Surface Weather Observations) published by Environment Canada. *PIREP: ::UACN10 CYQT 192128 ::YZ WG ::UA /OV YSP 090025 /TM 2120 /FL050 /TP BE99 /SK 020BKN040 110OVC /TA -14 /WV 030045 /TB MDT CAT 060-080 /IC LGT RIME 020-040 /RM LGT FZRA INC :Decoded as: ::Routine upper air report from Thunder Bay issued at 2128 UTC on the 19th of the month ::YZ is

Toronto Toronto ( ; or ) is the capital city of the Provinces and territories of Canada, Canadian province of Ontario. With a recorded population of 2,794,356 in 2021, it is the List of the largest municipalities in Canada by population, most pop ...

and WG is Winnipeg: these are the Flight Information Regions where the PIREP was issued ::Aircraft observation was east (090 degrees radial) of the

Marathon The marathon is a long-distance foot race with a distance of , usually run as a road race, but the distance can be covered on trail routes. The marathon can be completed by running or with a run/walk strategy. There are also wheelchair di ...

VOR/ DME at 2120 UTC. The aircraft was at and is a Beech 99. The clouds were broken at AMSL with tops at and an overcast layer at AMSL. The temperature is −14 degrees Celsius and the winds are from the northeast (030 degrees true) at . There is moderate clear air turbulence between and . There is light rime icing between and . Note this would indicate that the icing is picked up in the cloud. The remarks section says that light freezing rain was encountered in the cloud. *PIREP ::UACN10 CYXU 032133 ::YZ ::UA /OV YUX 09010 /TM 2120 /FL030 /TP C172 /TB MDT /RM MDT TURB BLO 050 CYKF CYXU :Decoded as: ::Routine message from

London London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary dow ...

, issued at 2133 UTC on the 3rd of the month ::The Flight Information Region is Toronto ::The aircraft was east (090 degrees radial) of the London VOR at 2120 UTC. The aircraft was at and was a

Cessna 172 The Cessna 172 Skyhawk is an American four-seat, single-engine, Monoplane#High, high wing, fixed-wing aircraft made by the Cessna Aircraft Company.

. The pilot reported moderate turbulence. The remarks says that the turbulence was below between

Kitchener Kitchener may refer to: People * Earl Kitchener, a title in the Peerage of the United Kingdom ** Herbert Kitchener, 1st Earl Kitchener (1850–1916), British Field Marshal and 1st Earl Kitchener ** Henry Kitchener, 2nd Earl Kitchener (1846–1937) ...

Waterloo Waterloo most commonly refers to: * Battle of Waterloo, a battle on 18 June 1815 in which Napoleon met his final defeat * Waterloo, Belgium, where the battle took place. Waterloo may also refer to: Other places Antarctica *King George Island (S ...

and London.

Soliciting PIREPs

In the US, air traffic controllers are required to solicit PIREPs upon request of other facilities or pilots, or when any of the following conditions exists or is forecast in their area:Aeronautical Information Manual (AIM) 7-1-20 Pilot Weather Reports (PIREPs)
/ref> * Ceilings at or below *Visibility at or less than * Thunderstorms and related phenomena * Turbulence of moderate degree or greater *Icing of light degree or greater *

Wind shear Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizon ...

* Volcanic ash clouds At least once hourly, terminal controllers must obtain a descent/climb-out PIREP, including cloud information and other related phenomena.

References

* Aeronautical Information Manual, dated April 3, 2014
p. 472

External links

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