What Is a PIREP? Pilot Weather Reports Explained

A PIREP, short for pilot weather report, is one of aviation’s most direct sources of real-world weather information. Instead of describing what a forecast expects or what an airport weather station sees at the surface, a PIREP tells other pilots and weather professionals what an aircraft actually encountered in flight at a specific place, time, and altitude.

That can include cloud bases or tops, turbulence, icing, flight visibility, precipitation, winds, temperature, or simply the absence of conditions that were expected. During seasonal transitions, when weather can change quickly, those observations can add useful context to a broader weather picture. Our fall flying tips for pilots cover several of the seasonal conditions that make current weather information especially important.

The FAA’s current Aeronautical Information Manual explains how PIREPs are collected, used, and transmitted. Just as important, it makes clear that pilots should not become so concerned with perfect formatting that they fail to pass along useful information.

What Is a PIREP and How Is It Different From a METAR or TAF?

A PIREP is an observation made by someone who is actually flying through the atmosphere. That makes it different from several other familiar aviation weather products.

• METAR: reports observed weather at or near a reporting station, normally an airport.
• TAF: forecasts expected conditions at a specific airport for a defined period.
• PIREP: reports conditions an aircraft actually encountered aloft at a particular location, time, and altitude.

That distinction matters because conditions above the surface can be quite different from what an airport weather station reports. A METAR may tell you what visibility and cloud cover look like at the airport, while a PIREP may tell you where the cloud tops are, whether the ride is smooth at 7,000 feet, or whether an aircraft is picking up ice in a particular layer.

No single report tells the whole story. A PIREP is most useful when considered alongside current observations, forecasts, advisories, radar, and the other information appropriate to the flight.

Why PIREPs Matter to Pilots and Forecasters

Some atmospheric conditions are difficult to observe accurately from the ground. Turbulence, icing, cloud tops, flight visibility, and conditions between reporting stations are obvious examples.

According to the FAA AIM, PIREPs are used by air traffic control facilities, Flight Service, and the National Weather Service. They may help controllers pass useful conditions to other aircraft, help briefers provide current information, and help forecasters verify or amend aviation forecasts and advisories.

That means a short report from one aircraft can become useful information for many other people planning or conducting flights through the same area.

When Does ATC Solicit PIREPs?

There is an important distinction here between an FAA requirement placed on air traffic facilities and guidance given to pilots.

The current FAA air traffic control order instructs controllers to solicit PIREPs when a report would be beneficial and when specified conditions exist or are forecast in their area. Those conditions include:

• ceilings at or below 5,000 feet;
• surface or aloft visibility of 5 miles or less;
• thunderstorms and related phenomena;
• moderate or greater turbulence;
• light or greater icing;
• wind shear;
• braking action reported as less than good;
• volcanic ash clouds; and
• certain indications associated with volcanic activity.

Those are instructions to ATC personnel. They should not be read as a blanket regulation requiring every general aviation pilot to file a PIREP whenever one of those conditions exists.

For pilots, the FAA AIM uses different language: it urges pilots to cooperate with PIREP requests and to promptly volunteer reports of significant conditions and other useful atmospheric information.

If you are already receiving VFR flight following, for example, the controller you are speaking with may ask about the ride, cloud tops, visibility, or another specific condition. That request is part of the broader PIREP collection system.

Routine UA vs. Urgent UUA PIREPs

PIREPs are distributed using one of two classifications: routine, identified as UA, or urgent, identified as UUA.

Routine PIREPs: UA

A routine PIREP is any report that does not meet the criteria for an urgent PIREP. The word “routine” does not mean unimportant.

A routine report could describe cloud bases and tops, moderate turbulence, light icing, flight visibility, temperature, or even the fact that conditions are better than forecast. Those observations can still be extremely useful to the next pilot and to weather forecasters.

Urgent PIREPs: UUA

The current FAA air traffic control order directs facilities to classify certain reports as urgent UUA PIREPs. Examples include:

• tornadoes, funnel clouds, or waterspouts;
• severe or extreme turbulence;
• severe icing;
• hail;
• specified low-level wind shear conditions;
• volcanic eruptions or volcanic ash; and
• other reported phenomena considered hazardous or potentially hazardous to flight operations.

The receiving facility handles the formal UA or UUA classification. From the pilot’s perspective, the more important task is to report the condition accurately and promptly using the appropriate terminology for what was actually encountered.

What Information Goes Into a PIREP?

When PIREPs are entered into the aviation weather system, they use standardized code groups. Pilots may see these codes when reading a raw PIREP:

• UA or UUA: routine or urgent report type
• /OV: location of the observation
• /TM: time in Coordinated Universal Time
• /FL: altitude or flight level
• /TP: aircraft type
• /SK: sky cover, including cloud layers
• /WX: weather, flight visibility, precipitation, or restrictions to visibility
• /TA: temperature in Celsius
• /WV: wind
• /TB: turbulence
• /IC: icing
• /RM: remarks

Not every PIREP contains every optional element. The FAA’s transmitted format includes the identifying information, location, time, altitude, and aircraft type along with the weather elements that are relevant to the observation.

Altitude and aircraft type are especially important when reporting turbulence or icing. A report has much more meaning when another pilot can tell what type of aircraft encountered the condition and at what altitude.

How Do Pilots Give a PIREP?

If you are already communicating with an FAA facility, the AIM says the report should generally be given to the facility with which communications are established. That may be Flight Service, an Air Route Traffic Control Center, or terminal ATC.

You do not need to speak in encoded slash groups over the radio. Tell the controller or specialist that you have a pilot report and provide the useful details of what you encountered. Location, time, altitude, aircraft type, and the actual weather condition are the core pieces to have in mind.

The FAA specifically advises pilots not to become overly concerned with strict PIREP format or phraseology. If clarification is needed, the receiving facility can ask for it. Pilots who want a broader refresher on aviation communications may also find our guide to aviation radio terms and why pilots say “niner” useful.

If a pilot cannot make the report by radio, the AIM says reporting the encountered conditions after landing to the nearest Flight Service Station or Weather Forecast Office can still be helpful.

The National Weather Service Aviation Weather Center also provides an online PIREP submission system for authorized users. Access requires registration and validation.

A Useful PIREP Does Not Have to Describe Bad Weather

One of the easiest misconceptions about PIREPs is that they are only worth making when something goes wrong.

The FAA’s controller guidance specifically notes that reports indicating a lack of forecast icing or turbulence are valuable to pilots and forecasters, particularly when adverse conditions were expected but did not develop or appear to have ended.

Sometimes the most useful weather report from another pilot is not “here is the hazard.” It is “the hazard everyone expected is not here at this altitude right now.”

A smooth ride report, an accurate cloud-top observation, or a report of no icing can help fill a gap in the weather picture. It does not prove that the same conditions exist everywhere nearby, but it gives the next pilot another current observation to evaluate.

How Should Pilots Use PIREPs in Weather Planning?

A PIREP is a snapshot. It describes what one aircraft encountered at a particular place, altitude, and time.

Weather moves. Icing layers change. Turbulence can vary considerably over relatively short distances or altitudes. Aircraft also respond differently to the same atmosphere.

For those reasons, a PIREP should not be treated as a guarantee that your aircraft will encounter the same conditions. It also should not be used by itself to decide whether a flight is safe or legal.

Instead, consider PIREPs as one part of a larger weather picture that may include current observations, forecasts, weather advisories, radar and satellite information, official briefings, aircraft limitations, and your own operating decisions.

Practical PIREP Habits for General Aviation Pilots

The following are practical habits, not a separate set of FAA regulatory requirements:

• Be timely. A current observation is generally more useful than one held until much later.
• Be specific about location and altitude. Conditions aloft can change substantially with both.
• Include the aircraft type. This is particularly useful for turbulence and icing reports.
• Describe what you actually encountered. Report observations rather than guessing about conditions outside the area you flew through.
• Use standard intensity terminology. The AIM provides definitions for reporting turbulence and icing intensity.
• Report useful good conditions too. Smooth air, unexpectedly high cloud bases, or the absence of forecast icing can be valuable observations.
• Keep the report concise. The goal is useful information, not a perfect recitation of encoded weather shorthand.
• Manage the airplane first. Make a report when workload and conditions allow you to do so without compromising aircraft control.

PIREPs work because pilots share what they are actually seeing and feeling in the atmosphere. A useful report can help another pilot refine a plan, help ATC understand conditions in its airspace, and give forecasters evidence about whether the atmosphere is behaving as expected.

This article is intended as general aviation education, not as a substitute for current FAA publications, National Weather Service information, aircraft operating guidance, flight instruction, or a complete preflight and inflight weather evaluation.

Frequently Asked Questions About PIREPs

What does PIREP stand for?

PIREP stands for pilot weather report. It is a report of actual atmospheric conditions encountered by an aircraft in flight, such as turbulence, icing, cloud layers, flight visibility, precipitation, temperature, or wind.

Are pilots required to submit PIREPs?

The FAA AIM urges pilots to cooperate with requests for PIREPs and to volunteer useful reports, but that guidance does not state a blanket requirement for every general aviation pilot to file a PIREP whenever weather is encountered. ATC, separately, has specific requirements for when controllers must solicit reports.

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

UA identifies a routine PIREP. UUA identifies an urgent PIREP involving specified hazardous conditions such as severe icing, severe or extreme turbulence, hail, certain low-level wind shear reports, volcanic activity, or another condition considered hazardous or potentially hazardous to flight operations.

How do I give a PIREP to ATC?

If you are already communicating with an FAA facility, tell the controller or specialist you have a pilot report and provide the relevant location, time, altitude, aircraft type, and observed conditions. The FAA AIM says pilots should not be overly concerned with strict PIREP format or phraseology because the receiving facility can request clarification when needed.

What information should I include in a PIREP?

A useful PIREP normally identifies where and when the condition was encountered, the aircraft’s altitude and type, and the relevant weather observation. Depending on the situation, that may include cloud layers, visibility, precipitation, temperature, wind, turbulence, icing, or other remarks.

Should pilots report smooth air or no icing?

Yes, when the information is useful. FAA guidance specifically notes that reports showing a lack of forecast icing or turbulence can be valuable, especially when adverse conditions were expected but did not develop or appear to have ended.

Can a PIREP replace a weather briefing or forecast?

No. A PIREP is one observation from a particular aircraft, location, altitude, and time. It should be evaluated with current forecasts, observations, advisories, and the other information appropriate to the flight rather than treated as a complete weather picture by itself.