The PIREP, the Pilot Weather Report That Only Comes From Someone Who Was Just There, and the Coded Data Most Students Skip Past in Their Briefing

A PIREP (Pilot Weather Report) is the only data source in your weather briefing that comes from a human who was actually in the air on your route. Forecasts can tell you what conditions might be; a pilot who flew that route 40 minutes ago can tell you what they were.

What Is a PIREP and Why Does It Matter?

PIREPs are voluntary weather observations filed by pilots in flight or just after landing. The FAA asks pilots to file them, Air Traffic Control relays them, weather briefers use them, and they appear in your briefing as a block of coded text. Most student pilots spend about three seconds on them before moving on. That’s a mistake.

Forecasts are models. PIREPs are ground truth. When a forecast says “occasional light turbulence below ten thousand feet,” it can’t account for aircraft type, pilot experience, or the exact corridor you’re flying. A pilot in the same airspace, in a similar airplane, reporting within the last hour, can.

What Are the Two Types of PIREPs?

There are two designations:

• UA - Routine PIREP
• UUA - Urgent PIREP

Urgent PIREPs are filed for severe or extreme turbulence, severe icing, or any condition that poses an immediate hazard to flight. When you see UUA at the top of a report, read every word before continuing your briefing.

How Do You Decode a PIREP?

Every PIREP follows a standard structure. Once you know the elements, it reads like a conversation rather than a cipher. Here is a representative example:

UA /OV STL020045 /TM 1630 /FL080 /TP C172 /SK BKN060 /TA -04 /IC LGT RIME /RM OCCASIONAL MDT IMC

UA - Report type. Routine.

OV - Location. STL is St. Louis Lambert. 020 is the radial. 045 is 45 nautical miles. This pilot was 45 miles to the northeast of the St. Louis VOR. Draw a line from the VOR on the 020 radial and that is where this observation was made.

TM - Time. 1630 Zulu. This is when the observation happened, not when it was filed or when you are reading it. A PIREP from three hours ago is historical context. A PIREP from twenty minutes ago is close to real time. Always check the time stamp before you interpret anything else.

FL - Altitude. Flight level 080 - 8,000 feet. Turbulence and icing are highly altitude-dependent. A pilot reporting smooth air at 12,000 feet tells you nothing about what is happening at 6,000. Match the PIREP altitude to your planned cruise altitude before drawing any conclusions.

TP - Aircraft type. C172 - Cessna 172. This matters. A Cessna 172 reporting light turbulence and a Boeing 737 reporting light turbulence are not the same experience. Large aircraft dampen bumps that are very noticeable in a light trainer. When reading a turbulence report, always consider who filed it and what they were flying. Light turbulence in a regional jet could be moderate or worse in your aircraft.

SK - Sky condition. BKN060 - broken at 6,000 feet. Sky condition in a PIREP is based on visual observation from the cockpit, not a sensor. It can give texture the automated surface observation cannot, but it can also be less precise. Treat it as one piece of the picture.

TA - Temperature. −4°C at 8,000 feet. Hold that number. Negative four Celsius in visible moisture places this squarely in the icing risk zone. Any time you are in cloud or precipitation with temperatures between approximately 0°C and −15°C, supercooled water droplets can exist and will freeze on contact with your airframe.

IC - Icing. LGT RIME - light rime icing. The pilot confirmed it. Rime ice forms when small supercooled droplets freeze almost instantly on the leading edges. It looks white and opaque. Light icing builds at less than approximately one-quarter inch per hour - not an immediate emergency, but 45 minutes of light icing in a trainer with no de-icing equipment will create a serious problem.

Light icing in a PIREP is a warning, not permission. It tells you conditions are right and accumulation is happening. Whether your specific aircraft can handle it is a separate question. For most training aircraft, the answer is: do not find out.

RM - Remarks. OCCASIONAL MDT IMC. This is plain-language text the pilot adds for anything that doesn’t fit the standard elements. This pilot was intermittently encountering moderate instrument meteorological conditions - punching through cloud or dropping below three miles visibility, but not continuously. Always read the remarks. Pilots write their most honest and useful observations there.

What Do Turbulence Intensity Levels Actually Mean?

The turbulence intensity scale runs from smooth to extreme:

• Smooth - No turbulence.
• Light - Slight, erratic changes in altitude or attitude. Passengers feel it, unsecured objects shift, but nothing alarming.
• Moderate - Noticeable changes in altitude or attitude, but the aircraft remains in positive control. A real jolt. Uncomfortable but manageable.
• Severe - Large, abrupt changes. The aircraft may be momentarily out of control. Occupants are forced against their restraints. This category causes injuries. When you see SEV in a PIREP, you do not fly through that airspace.
• Extreme - The aircraft is violently tossed about and practically uncontrollable. Can cause structural damage. No aircraft, ever.

What Do Icing Intensity Levels and Ice Types Mean?

The icing intensity scale follows similar logic:

• Trace - Detectable but builds slowly. De-icing equipment handles it easily.
• Light - Builds at a rate de-icing equipment can manage intermittently. Without de-icing equipment, light icing is a time-sensitive problem.
• Moderate - Requires continuous de-icing and may not be fully controllable even with it. In an unequipped aircraft, moderate icing is an emergency developing in real time.
• Severe - Accumulation cannot be controlled even with equipment. No aircraft should be in severe icing conditions.

Ice type matters too:

• Rime ice - White, opaque, rough. Builds on leading edges from small supercooled droplets freezing instantly on contact.
• Clear ice (glaze ice) - Dense, transparent, and heavy. Forms from larger droplets or freezing rain and can conform to the entire airframe. Adds significant weight and is harder to spot visually.
• Mixed icing - A combination of rime and clear. Often the most hazardous of the three.

Where Do You Find PIREPs in a Weather Briefing?

Through the standard briefing at 1800wxbrief.com, PIREPs appear in the weather section of your summary. In apps like ForeFlight or Garmin Pilot, they show up as colored icons along your route - green for smooth or negative reports, blue for icing, red for turbulence.

The color coding gives you a quick scan, but don’t stop there. Click the icon and read the actual coded data. The color tells you something was reported. The report tells you what, at what altitude, in what airplane, and when.

Most electronic flight bags let you filter PIREPs by type and time window. Within two hours is genuinely useful. Beyond three hours, conditions may have shifted significantly. Set that filter before you start reviewing.

One important caution: PIREPs are sparse. In many parts of the country, especially at lower altitudes on weekday afternoons, you may find none along your route. No reports does not mean no weather. It may simply mean nobody filed. PIREPs are one layer in a multi-layer picture, not the whole answer.

How Do You File a PIREP?

You can file a PIREP yourself, and you should. The FAA encourages it, ATC accepts them, and every report you file is information another pilot will use to make a better decision.

When you encounter weather worth reporting, contact ATC or Flight Service and say: “I’d like to file a PIREP.” They will walk you through the questions. Provide your location referenced to a VOR or fix, your altitude, your aircraft type, and what you are observing - sky condition, visibility, temperature, and any turbulence or icing.

Negative PIREPs - reports of smooth air and clear conditions at a specific altitude - are just as valuable as adverse reports. They help the next pilot know what to expect and help forecasters validate their products against reality.

In ForeFlight, you can file directly from the app under the weather menu. The interface walks you through each element and takes about two minutes.

How Do PIREPs Fit Into a Complete Weather Briefing?

PIREPs work best as ground truth layered on top of forecast products. A practical briefing sequence:

1. Start with the Area Forecast Discussion to understand what the forecasters are thinking.
2. Check G-AIRMETs for broad icing and IFR hazards.
3. Pull the TAF for your destination.
4. Then go to PIREPs for real-world confirmation.

If your G-AIRMET shows AIRMET Zulu for moderate icing above 8,000 feet, look for any pilot who flew through that airspace in the last 90 minutes. Three clean PIREPs from that altitude in the last hour improve the picture - but they don’t replace the forecast. Conditions change.

PIREPs matter most when the forecast is ambiguous. When the guidance says “occasional” or “isolated” and you are sitting on the fence about a go/no-go, a recent PIREP along your route can tip the scales - not by itself, but as the piece that confirms or contradicts what the forecast is suggesting.

When you land, file the PIREP for your flight. Not because it helps you. Because it helps the pilot who is going to look at your route three hours later.

What Does the ACS Expect You to Know About PIREPs?

The Airmen Certification Standards (ACS) expect you to obtain, interpret, and apply PIREPs. During your oral exam, your Designated Pilot Examiner (DPE) may hand you a PIREP printout and ask you to decode it and explain what it means for the proposed flight - not just read it back, but explain what it means for your airplane, at your altitude, on your route.

The examiner is looking for a pilot who treats PIREPs as a decision-making tool, not a box to check on a briefing checklist.

Key Takeaways

• Always check the time stamp first. A PIREP from 20 minutes ago is near real-time; one from three hours ago is historical context that may no longer reflect current conditions.
• Adjust for aircraft type. Light turbulence reported by a regional jet could be moderate or worse in a Cessna 172. The TP field tells you who filed the report.
• Match PIREP altitude to your cruise altitude. A report at 12,000 feet tells you nothing about conditions at 6,000 feet. Always check the FL element against your planned altitude.
• Light icing is a warning, not clearance. In an unequipped aircraft, light icing is a time-sensitive problem; moderate icing is an emergency developing in real time.
• Read the remarks and file your own PIREPs. The RM field contains the most direct and honest information in the report, and negative PIREPs are as valuable to the next pilot as adverse ones.