Decoding a PIREP
A PIREP is a weather report made by a pilot in flight. It is the only report of what the air is actually doing up there (turbulence, icing, cloud tops), so it fills the gaps between ground observations. Each field is tagged with a / prefix.
Two report types come first:
UA= a routine pilot report.UUA= an URGENT report, filed for hazards: severe turbulence or icing, low-level wind shear, hail, or volcanic ash.
CYYZ UA /OV CYYZ /TM 1345 /FL080 /TP C172 /SK BKN050 /TA -03 /WV 24030KT /TB MOD /IC LGT RIME
| Field | Meaning |
|---|---|
/OV |
location (station, or bearing/distance from one) |
/TM |
time, UTC |
/FL |
altitude as a flight level, hundreds of feet: FL080 = 8,000 ft ASL (PIREP and GFA heights are ASL, unlike METAR/TAF which are AGL) |
/TP |
aircraft type (here a C172) |
/SK |
sky / cloud layers |
/TA |
outside air temperature, °C (a leading - marks sub-zero, e.g. -03) |
/WV |
wind (direction/speed), true |
/TB |
turbulence intensity: LGT, MOD, SEV (no trace level) |
/IC |
icing intensity and type: TRC (trace), LGT, MOD, SEV + RIME/CLR/MX |
/RM |
remarks (plain language) |
Icing has a fourth, lower level, TRC (trace), that turbulence does not.
Trap: swapping UA (routine) and UUA (urgent), reading /FL080 as 80 ft or 80,000 ft instead of 8,000 ft ASL, or mixing up the field prefixes (reading /TB turbulence as /IC icing, or /TP type as /TM time).
References
- TC AIM MET 2.1 (PIREP example, fields)
- TC AIM MET 2.2.2 (turbulence intensities)
- TC AIM MET 2.4 (icing intensities, Table 2.3)
- TC AIM MET 1.2.2 (PIREP heights ASL)