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

A UA is a routine pilot report, while a UUA is urgent, flagging hazardous conditions like severe turbulence, severe icing, funnel clouds, low-level wind shear, or volcanic ash that other pilots need to know about immediately.

Do I need to know the letter codes to file a PIREP?

No. The codes are only for reading printed reports. To file, you just describe your location, altitude, aircraft type, and conditions in plain English, and the specialist translates it for you.

Who can I contact to file a PIREP?

You can file with a Flight Service Station, on Flight Watch frequencies, or simply tell the air traffic controller you're already talking to that you'd like to file a PIREP.

Should I file a PIREP if the weather is smooth and clear?

Yes. Positive or "negative" reports - like smooth air on top of a layer or a higher-than-forecast ceiling - are extremely valuable because they help the next pilot make an informed go/no-go decision.

How much should I trust a PIREP that's an hour old?

Treat it as a snapshot of one moment, place, and aircraft. Always check the timestamp and use it to sharpen your weather picture rather than replace your own in-flight judgment, since conditions change.

The PIREP, the One Weather Report Made by a Human in the Air, and How to Read One and File One on Your Next Flight

A PIREP (pilot report) is the one piece of your weather briefing not generated by a computer or ground-based forecaster - it’s filed by a pilot actually in the air, describing the real conditions they encountered. To read one, you decode a handful of lettered fields covering location, altitude, aircraft type, clouds, turbulence, and icing; to file one, you simply tell a controller or Flight Service five things in plain English: where you are, your altitude, your aircraft type, and what you’re seeing. PIREPs are the most current, most honest weather data in the system, and every pilot is expected to both use them and contribute them.

What Is a PIREP and Why Does It Matter?

Every automated weather product you pull for a briefing - METARs, TAFs, winds aloft, the graphical forecast - shares the same blind spot. These tools are excellent at describing surface conditions and at telling you what a model predicts up high. They are not good at telling you what it actually feels like at 7,500 feet over a ridge line right now.

Is the cloud base really where the forecast says? Is there ice on the leading edge? Is the ride smooth, or will it rattle your fillings loose? How far down does that haze layer go before you break into clear air?

A machine guesses. A pilot knows, because a pilot is sitting in it. A PIREP is a report filed by a pilot, in flight or just after landing, describing the actual conditions they encountered. It is the single most current, most honest, and most human piece of weather information in the entire system.

How Do I Read a PIREP?

They look like alphabet soup the first time you see one. Once someone walks you through the code, it becomes plain English and you never unsee it.

There are two types. A routine report is coded UA. An urgent report is coded UUA. That double-U at the front is your flag that a pilot encountered something serious enough to reach other pilots fast - severe turbulence, severe icing, a funnel cloud, low-level wind shear, or volcanic ash. When you see UUA, pay attention: a fellow aviator raised their hand and said this one’s serious.

After the tag, the report breaks into fields, each with a letter code. You don’t need every field memorized - you just need to recognize them as they scroll by:

OV (location): Where the report was made, usually relative to a Navaid or airport - for example, 30 miles southwest of a fix.
TM (time): Given in Zulu, in the four-digit clock.
FL (flight level/altitude): The height it was reported at. If the ride got rough at 8,000, that’s the number here.
TP (aircraft type): This matters more than students realize. If a heavy jet reports light chop and you’re in a Cessna 172, that same air might toss you around like a cork. Read the airplane, then read the ride.
SK (sky cover): Cloud bases and tops, and whether it was scattered, broken, or overcast - gold for a VFR pilot hunting a real hole to climb through.
WX (weather and visibility): Flight visibility, haze, precipitation - what they could actually see out the window.
TA (temperature): In Celsius. That little number can be the difference between clear flying and picking up ice.
WV (wind): Direction and speed up where you’ll be, which is often very different from the surface.
TB (turbulence): Light, moderate, severe, or extreme.
IC (icing): Trace, light, moderate, or severe.
RM (remarks): Plain language - often the most useful line in the whole report.

What Do the Turbulence and Icing Terms Actually Mean?

The turbulence words aren’t casual - they’re defined terms, and pilots pick them on purpose. Light is a little bumpy; your coffee’s fine. Moderate means you’re straining against the belts, unsecured objects are moving, and you’re working to hold altitude. Severe means the airplane is momentarily out of control and objects are thrown around the cabin. When a pilot files moderate or worse, believe them.

Icing runs on the same scale - trace, light, moderate, severe - and it deserves cold, humorless respect. Ice changes the shape of your wing, and a wing that isn’t the shape the engineer designed does not make the lift you’re counting on.

How Does a PIREP Change a Real Go/No-Go Decision?

Consider a morning cross-country of 200 nautical miles. The destination TAF calls for a marginal ceiling - broken clouds around 3,000 feet. You’re a VFR pilot, so that ceiling is your whole world today. You need to know: is it really 3,000, or is it lower? The difference between 3,000 and 1,500 feet over rising terrain is the difference between a nice flight and a very bad decision.

You pull the PIREPs along your route, and there it is: a UA filed 40 minutes ago by a Piper, at your altitude, 30 miles north of your midpoint. Sky cover broken at 2,200 feet, tops at 4,000. Remarks: bases ragged and lowering to the north.

Feel what just happened. A forecast told you 3,000. A human who was actually there 40 minutes ago told you 2,200 and getting worse in the direction you’re headed. That report did more for your decision than every satellite image on the screen - and it existed only because one pilot took twenty seconds to file it.

How Do I File a PIREP?

Here’s the good news: you do not need to know the letter codes to file one. Those codes are for reading the printout. To file, you just talk.

Call up a Flight Service Station, use Flight Watch frequencies, or simply tell the controller you’re already talking to, “I’d like to file a PIREP.” Then give them five things in plain words:

Where you are (location)
What time it is (they’ll usually handle this)
Your altitude
Your aircraft type
What you’re seeing (conditions)

Location, altitude, airplane, conditions. The specialist takes your plain English and translates it into the coded format. You never touch a letter code - you just describe your sky.

This is also what the Airman Certification Standards (ACS) care about. On your checkride, in the weather and preflight planning tasks, the examiner wants to see you treat PIREPs as a two-way street: use them as a source during planning, and understand that you’re expected to contribute them too. The regulations lean on pilots to report hazardous conditions - unforecast ice, a ceiling a thousand feet lower than advertised, a ride worse than the outlook suggested. When you encounter it, you are the sensor now. Nobody else is up there feeling what you’re feeling.

Should I File a PIREP When the Weather Is Good?

Yes - and it may be the most valuable report you’ll ever file. Everybody assumes a PIREP has to be bad news, but the negative PIREP and the “smooth on top” report are among the most useful in the system.

Climb through a broken layer, break out into smooth, glassy air at 6,500 feet, and key the mike: “Tops 4,000, smooth on top, unlimited visibility.” You just told the pilot behind you the layer is climbable and there’s a beautiful day sitting on top of it. You turned their maybe into an informed yes. Good news is data too. File it.

What Are the Limits of a PIREP?

A PIREP is a snapshot of one moment, at one place, from one airplane - and weather moves. That report of a 2,200-foot ceiling was true 40 minutes ago, 30 miles north. It is not a guarantee about your position twenty minutes from now.

Read the timestamp. Note how old the report is. Use it to sharpen your picture, not to replace your judgment. The pilot who files is doing you a service, but conditions can still change on both of you.

Key Takeaways

A PIREP is the only weather report made by a human in the air; it’s the most current and honest data in your briefing.
UA marks a routine report; UUA marks an urgent one (severe turbulence, severe icing, funnel clouds, wind shear, or volcanic ash).
To read one, recognize the lettered fields - TP (aircraft type) and TM (time) are critical context for judging whether a report applies to you.
To file one, you don’t need any codes: give location, altitude, aircraft type, and conditions to a controller or Flight Service.
Good-news reports matter too - “smooth on top” and higher-than-forecast ceilings are gifts to the next pilot in line.