Pilot reports and the real-time weather intelligence that only comes from someone who is already up there
Learn how to read, interpret, and file PIREPs to get real-time weather intelligence that forecasts alone cannot provide.
Every weather forecast is a prediction, but a PIREP — a pilot report — is real-time data from someone flying through the air right now. PIREPs fill the critical gap between surface observations (METARs), forecasts (TAFs), and what the atmosphere is actually doing at altitude along your route. Understanding how to read and file them is both a practical safety skill and a checkride requirement under the Airman Certification Standards.
What Is a PIREP and Why Does It Matter?
A PIREP is a weather observation made by a pilot in flight and relayed to ATC or Flight Service. It gets encoded into a standard format and distributed so that every pilot pulling a briefing afterward has eyes-in-the-sky data — turbulence, icing, cloud tops, visibility, and wind conditions reported from actual experience rather than computer models.
METARs tell you what’s happening at the surface. TAFs project what’s expected over the next several hours. Prog charts show the big picture. But none of them tell you what the air is doing between the surface and your cruising altitude, right now, along your route. That’s the gap PIREPs fill.
How Do You Decode a PIREP?
PIREPs follow a fixed format. Once you learn the field order, they read like a sentence.
UA or UUA — The report type comes first. UA is a routine pilot report. UUA is urgent, filed for severe turbulence, severe icing, low-level wind shear, tornadoes, volcanic ash, or hail. A UUA means someone just encountered dangerous conditions.
/OV — Location. Where the pilot was when they made the report. It might read “OV KCI” (over Kansas City) or give a bearing and distance, like “250°/30 NM from MEM.”
/TM — Time in Zulu, four digits (hours and minutes). A PIREP from 20 minutes ago is gold. A PIREP from four hours ago is context at best.
/FL — Flight level (altitude). FL060 means 6,000 feet. FL120 means 12,000 feet. FL UNKN means the altitude is unknown — treat that report with less confidence.
/TP — Aircraft type. This field matters more than most students realize. Turbulence that a Cessna 172 reports as moderate might barely register in a Boeing 737. Always factor aircraft type into your interpretation.
The remaining fields cover sky conditions, visibility, temperature, wind, turbulence, and icing. Not every PIREP includes all of them — pilots report what’s relevant to their experience.
How Is Turbulence Reported in PIREPs?
Turbulence is coded in four levels:
- Light — Slight, erratic changes in altitude or attitude. Minor discomfort.
- Moderate — Noticeable changes in altitude or attitude, but the aircraft remains under positive control. Passengers won’t be happy.
- Severe — Large, abrupt changes. The aircraft may momentarily be out of control. Airspeed fluctuates wildly. Avoid this in a training airplane.
- Extreme — The aircraft is violently tossed and practically impossible to control. No pilot intentionally flies into extreme turbulence.
Reports may also specify the cause: CAT (clear air turbulence), convective, thermal, or mechanical (terrain-induced). Knowing the cause helps you determine whether you can avoid it by changing altitude or route.
How Is Icing Reported in PIREPs?
Icing intensity uses four levels:
- Trace — Barely perceptible accumulation.
- Light — Could become a problem during prolonged exposure (more than an hour).
- Moderate — Even short encounters are potentially hazardous. Change altitude or heading immediately.
- Severe — Accumulation rate exceeds de-icing equipment capability.
In a training airplane with no de-icing capability, anything above trace demands your full attention.
The report also identifies the type of ice:
- Rime ice — Rough, milky white, forms in small droplets at colder temperatures.
- Clear ice — Smooth, transparent, heavy, forms in larger droplets. Much harder to deal with.
- Mixed — Both rime and clear.
A PIREP reporting moderate clear icing at your planned altitude is a serious red flag that should prompt you to rethink the flight.
Where Do You Find PIREPs During Preflight?
- Leidos Flight Service (1-800-WX-BRIEF) includes PIREPs along your route in a standard briefing.
- ForeFlight and other EFBs display PIREPs as tappable markers on the map with decoded reports.
- Aviation Weather Center (aviationweather.gov) has a PIREP map showing all reports plotted geographically.
When reviewing PIREPs, don’t just glance — actually evaluate them:
- Check the time. Is this report 20 minutes old or 4 hours old?
- Check the altitude. Is the pilot at your planned cruising altitude or 10,000 feet above it?
- Check the aircraft type. A King Air handles turbulence very differently than a Cherokee.
- Check the trend. Are conditions worsening over time, or improving?
How Do You File a PIREP?
Filing a PIREP is straightforward, and the FAA encourages every pilot to do it.
On frequency with ATC: Simply tell the controller. For example: “Kansas City Center, Cessna 3456J, pilot report. Moderate turbulence at six thousand five hundred, twenty miles southwest of Topeka.” They’ll forward it to Flight Service for encoding.
On Flight Service frequency: Contact them on 122.0, the universal Flight Service frequency available in most of the country.
After landing by phone: Call Leidos Flight Service and file it after the fact. Still valuable, especially for significant conditions.
You don’t need to know the encoding — just speak plain English. The briefer or controller handles the formatting. Be specific: instead of “it’s bumpy,” say “moderate turbulence at 7,500 feet, 20 miles north of Springfield.” Precision makes the report actionable.
When Should You File a PIREP?
File a PIREP whenever you encounter:
- Any icing — even trace
- Moderate or greater turbulence
- Visibility or cloud conditions significantly different from the forecast
- Low-level wind shear — the pilot on approach behind you needs to know immediately
Negative PIREPs are equally valuable. If the forecast called for moderate turbulence and you’re flying through glass-smooth air, reporting that tells the next pilot the forecast was wrong in a good way and gives forecasters real data to refine their models.
Putting It All Together: A Real Scenario
You’re planning a cross-country from Missouri to northern Arkansas in late fall. A front is pushing through, and temperatures are dropping. Your TAF shows broken ceilings at 4,000 feet with occasional visibility drops. Then you check PIREPs from the last hour:
- Light rime icing at 5,000 feet, 30 NM south of your departure — filed by a Piper Archer
- Moderate turbulence at 4,500 feet, just north of Springfield — filed by a Cessna Skylane
- Cloud tops at 6,000 feet, smooth on top — filed by a Bonanza
Now you have ground truth the forecasts didn’t give you. The icing is confirmed. The turbulence is real. The clouds extend to 6,000 feet. If your airplane can’t climb above 6,000 or you lack icing capability and training, this flight needs a different plan — wait for the front to pass, stay below the clouds, or pick a different route entirely.
And once airborne, if conditions change, you close the loop by filing your own report for the pilot departing an hour behind you.
What Will the Examiner Ask About PIREPs?
Expect your examiner to test whether you can read, interpret, and apply PIREPs as part of a complete weather picture. They may hand you an encoded PIREP and ask you to decode it. They may also ask when you would file one. The answer: anytime you see something the next pilot needs to know.
Key Takeaways
- PIREPs provide real-time, in-flight weather data that forecasts, METARs, and TAFs cannot — filling the gap between surface observations and altitude conditions along your route.
- Decode PIREPs by learning the fixed field order: report type (UA/UUA), location (/OV), time (/TM), altitude (/FL), aircraft type (/TP), and weather conditions.
- Always consider aircraft type when interpreting turbulence and icing reports — a light airplane and a jet experience the same air very differently.
- File PIREPs whenever you encounter icing, moderate-or-greater turbulence, wind shear, or conditions that differ from the forecast — including negative reports when conditions are better than predicted.
- The ACS requires you to read, interpret, and apply PIREPs in your weather decision-making, making this a checkride topic.
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