PIREP Codes: Every Field and Hazard Abbreviation
A PIREP is the only weather product written by somebody who was actually in the air. It is built from tagged fields rather than a fixed sequence, so the codes below are the whole vocabulary you need to read one. Every table here is the set of values the wxdecoder parser reads.
The tagged fields
Each field opens with a slash and two letters, and runs until the next slash. Not every report carries every field, and they usually appear in this order.
| Code | What it means |
|---|---|
/OV |
location, usually a fix with a bearing and distance |
/TM |
time the conditions were met, in hours and minutes Zulu |
/FL |
altitude, as a flight level; UNKN when the pilot did not give one |
/TP |
aircraft type, which sets the scale every intensity word is measured on |
/SK |
sky cover, including cloud bases and tops |
/WX |
flight visibility and weather met in the air |
/TA |
outside air temperature in Celsius |
/WV |
wind direction and speed at altitude |
/TB |
turbulence: frequency, intensity and type |
/IC |
icing: intensity, ice type and the altitude band |
/RM |
remarks, in plain words |
Intensity
Shared by the turbulence and icing fields. The words are defined by what happens to the aircraft, which is what makes them reportable by any pilot.
| Code | What it means |
|---|---|
EXTRM, EXTREME |
extreme |
LGT, LT |
light |
MOD |
moderate |
NEG, NIL |
none reported |
SEV |
severe |
SMOOTH, SMTH |
smooth |
TRACE, TRC |
trace |
Frequency
These come before the intensity and say how much of the time it was there.
| Code | What it means |
|---|---|
CONS, CONT |
continuous |
INTMT |
intermittent |
ISOL |
isolated |
OCNL |
occasional |
Ice type
Follows the intensity in an icing field. Clear ice is denser, bonds harder and runs back behind the protected surfaces, so a moderate clear report is worse than a moderate rime one.
| Code | What it means |
|---|---|
CLR, CLEAR |
clear |
MX, MXD, MIXED |
mixed |
RIME |
rime |
Turbulence type
Follows the intensity in a turbulence field. Chop is the one to read carefully: it rattles the aircraft without moving it off its flight path.
| Code | What it means |
|---|---|
CAT |
clear-air turbulence |
CHOP |
chop |
LLWS |
low-level wind shear |
MWAVE |
mountain wave |
A worked example
Put the tables together and a full report reads straight through.
KDFW UA /OV DFW360015 /TM 1930 /FL085 /TP C172 /SK BKN050-TOP070 /TB LGT /IC NEG /RM SMOOTH BELOW
A routine report filed against Dallas Fort Worth. The aircraft was 15 miles on the 360 radial at 8500 feet, a Cessna 172, at 1930 Zulu. Broken cloud based at 5000 with tops at 7000. Light turbulence. No ice at all. And the remark adds that it was smooth lower down.
Read /TP before you weigh /TB or /IC. Moderate turbulence in a 172 is not moderate turbulence in a jet.
Frequently asked questions
What is the difference between UA and UUA?
UA is routine. UUA is urgent, used for severe turbulence, severe icing, wind shear, tornadoes, hail or volcanic ash. Urgent reports move through the distribution system ahead of routine ones.
What does NEG mean in a PIREP?
The pilot met none of that hazard. It is a real report rather than a blank, and a run of negative reports through a forecast icing band is strong evidence the layer is currently clean.
Why does the aircraft type matter so much?
Because the intensity words describe what happened to the aircraft, not a property of the air. The same turbulence moves a light single far more than a transport jet, so the type sets the scale.
Do AIREPs use these same codes?
The hazard words are the same, but an AIREP has no slashes. It starts with ARP and its fields sit in fixed positions, so you find them by order rather than by tag.