Every other weather product is a computer's opinion. A PIREP is a person who was up there, telling you what the air did to their aeroplane.

That makes it the most valuable thing on a briefing. It is also the most skipped. It arrives as a run of slashes and abbreviations, and nobody sits you down and teaches them. A PIREP decoder turns those fields back into sentences, and the fields are worth learning even if you use one.

A PIREP is a set of slash-delimited fields. /OV is where, /FL is how high in hundreds of feet MSL, /TP is the aircraft, /TB is turbulence and /IC is icing. UA is routine and UUA is urgent. The one that catches people: cloud heights in a PIREP are MSL, not the AGL you read in a METAR or TAF.

What's New in PIREP Reporting for 2026

The format has not changed. What has changed is how many reports are machine generated rather than typed by a pilot.

AIREPs arrive as automatic downlinks from the aircraft, carrying position, level, temperature and wind with no pilot involved. They use a different layout with no slashes. A decoder built only for the UA format shows you nothing for them.

The other shift is volume at altitude versus volume down low. Airline downlinks cover the flight levels densely. The band where light aircraft actually fly, from about 2 to 8 thousand feet, depends on pilots filing by hand. That is a good argument for filing one yourself.

What a PIREP Decoder Has to Split Apart

A PIREP is not positional like a METAR. It is a set of tagged fields in a conventional but not guaranteed order.

Here is a complete one:

KDFW UA /OV DFW360015 /TM 0930 /FL085 /TP C172 /SK BKN050-TOP070 /TB LGT /IC NEG /RM SMOOTH BELOW

The fields, in the order they usually appear:

• /OV location, as a fix with a radial and distance, a bare identifier, or a leg between two points
• /TM time in UTC, four digits
• /FL altitude in hundreds of feet MSL
• /TP aircraft type
• /SK sky cover and cloud tops
• /WX flight visibility and weather
• /TA outside air temperature in Celsius
• /WV wind at altitude
• /TB turbulence
• /IC icing
• /RM remarks, and often the most useful field in the report

The station in front of UA is the facility the report is filed against. It is usually the nearest reporting station, not where the aircraft was. The position lives in /OV.

Three codes in /FL are not altitudes at all. DURC means during climb, DURD means during descent, and UNKN means not given. A report filed during a climb covers a band rather than one level, which is often more useful.

UA and UUA: Why the Extra U Matters

UA is a routine pilot report. UUA is urgent, and it is not decoration.

An urgent report is reserved for a short list: severe or extreme turbulence, severe icing, hail, low level wind shear, a tornado or funnel cloud, and volcanic ash. Somebody had a bad enough time to reach for the urgent form.

If you scan nothing else on a page of pilot reports, scan for the second U.

The /TB Turbulence Field

The turbulence field reads as frequency, then intensity, then character, then an optional altitude band. Not all four are always there.

The intensity words:

• NEG none encountered
• LGT light
• MOD moderate
• SEV severe
• EXTRM extreme

The frequency words:

• OCNL occasional, less than one third of the time
• INTMT intermittent, one third to two thirds
• CONS or CONT continuous, more than two thirds

And the character:

• CHOP rapid rhythmic bumpiness with little change in altitude or attitude
• CAT clear air turbulence, which gives no visual warning at all

So /TB CONS LGT CHOP is continuous light chop. /TB MOD 150-100 is moderate turbulence between 10 and 15 thousand feet, written descending because the pilot was.

Read /TP before you read /TB. Moderate in a C172 and moderate in an airliner are the same word for very different air. The scale is defined by what the aircraft does, not by what the atmosphere does.

The /IC Icing Field

Icing uses the same intensity words plus a type, and the type is the part worth having.

• RIME opaque and milky, builds on the leading edges
• CLR clear, glossy and hard, much harder to shed
• MX mixed
• TRACE perceptible, but accumulating slower than it comes off

So /IC LGT RIME 140-260 is light rime icing between 14 and 26 thousand feet.

An icing PIREP is worth more than an icing forecast for a simple reason. A forecast says the conditions support ice. A PIREP says an aeroplane went through it and ice formed, which removes the question of whether the moisture and the temperature actually lined up.

Cloud Heights in a PIREP Are MSL

This is the mistake to inoculate yourself against, because nothing in the report warns you.

In a METAR or a TAF, cloud bases are height above ground. In a PIREP, cloud heights are above mean sea level unless the pilot says otherwise.

So /SK BKN050-TOP070 is broken cloud at 5 thousand feet MSL, tops at 7 thousand. At a field sitting at 5 thousand feet, that layer is on the deck, not a comfortable circuit height above you. Read the /SK field against field elevation every time.

TOPUNKN in the tops position means the pilot could not see the top, which is itself information if you were planning to climb through.

What a Good PIREP Decoder Does With NEG

/TB NEG looks like an empty report. It is the opposite.

Somebody flew that route, at that level, at that time, and found smooth air. When the forecast says moderate turbulence is possible, a run of NEG reports along your route at your altitude is evidence against it.

The absence of any reports is not the same thing. No PIREPs on a quiet Tuesday morning means nobody has been up, not that the air is smooth. Reports are evidence. Silence is not.

FAQ

What is the difference between UA and UUA in a PIREP?

UA is a routine pilot report. UUA is urgent, reserved for severe turbulence or icing, hail, low level wind shear, a tornado, or volcanic ash. If a page of reports contains a UUA, read that one before you read any of the others.

What does /FL085 mean in a PIREP?

The pilot was at 8,500 feet MSL. The /FL field is hundreds of feet above mean sea level. It is not a flight level in the ICAO sense, and it is not height above ground. DURC or DURD there means climbing or descending instead.

Are PIREP cloud heights MSL or AGL?

MSL, unless the pilot says otherwise. This is the opposite of a METAR or TAF, where cloud bases are above ground level. It is the single most common way a PIREP gets misread, especially at a high elevation airfield.

What does /TB CONS LGT CHOP mean?

Continuous light chop. CONS is the frequency, LGT is the intensity, and CHOP is the character: rapid rhythmic bumpiness with little change in altitude or attitude. Continuous means it was happening more than two thirds of the time.

What is an AIREP and how is it different?

An AIREP is an automatic downlink from the aircraft rather than a report typed by a pilot. It uses a positional layout beginning with ARP, with no slash delimited fields, so a decoder written only for the UA format cannot read one.

Verdict on PIREP Decoding

A PIREP decoder is worth using, and the fields are worth knowing anyway, because the report is short enough that you will often read it faster than you can paste it.

Learn four things and the rest follows. UUA means stop and read. /FL is hundreds of feet MSL. /TB and /IC run frequency, then intensity, then type. And /SK heights are MSL when everything else that day was above ground.

Paste one into the WxDecoder decoder and it reads both the slash delimited form and the positional AIREP form, showing the raw field beside the plain English so you can check the decode rather than take it on trust. Then go and file one, because the band where you actually fly only has reports in it if pilots like you put them there.

Last updated August 29, 2026