Pireps: The Firsthand Weather Reports Hidden Inside Your Briefing

Pilot weather reports - PIREPs - are eyewitness accounts from pilots who were actually in the air, at a specific location and altitude, at a specific time. Every other product in your weather briefing is a forecast or a model output. A PIREP is an observation. That distinction matters most on the days when weather is actually marginal.

Why PIREPs Are Different From Everything Else in Your Briefing

Your standard weather briefing is built primarily from model-derived data. The area forecast is a meteorologist’s interpretation of computer models. TAFs are human-generated predictions about conditions at a specific airport. Winds aloft forecasts come from upper-air soundings and model output.

All of that is valuable. None of it is ground truth.

A PIREP tells you where the cloud tops actually are, not where the model predicted they’d be. It tells you that moderate turbulence exists at 8,000 feet even when the forecast called for light. It tells you that icing forecast for 10,000 feet is actually starting at 7,000 feet.

The gap between forecast and reality is exactly where PIREPs live - and on days when you most need accurate weather information, that gap is usually widest.

How Do I Read a PIREP?

PIREPs use a compact coded format. Once you learn the sequence, reading them becomes fast.

A routine PIREP starts with UA (Upper Air - shorthand for aircraft observation). An urgent PIREP starts with UUA. After the identifier, a series of elements separated by slashes follows a consistent order:

• OV - Location (a fix, VOR, or airport identifier with bearing and distance)
• TM - Time in Zulu
• FL - Altitude in hundreds of feet (FL090 = 9,000 feet)
• TP - Aircraft type
• SK - Sky cover and cloud heights
• WX - Weather (precipitation, visibility restrictions)
• TA - Temperature at altitude in Celsius
• TB - Turbulence
• IC - Icing

Here’s a real PIREP decoded step by step:

UA /OV MEM030050 /TM 1423 /FL090 /TP C172 /SK BKN075 /TA -09 /TB MODT

• OV MEM030050 - Observation on a bearing of 030° from Memphis International, 50 miles out (roughly northeast of Memphis)
• TM 1423 - Time was 1423 Zulu
• FL090 - Altitude was 9,000 feet
• TP C172 - Aircraft type was a Cessna 172
• SK BKN075 - Broken clouds below the aircraft at 7,500 feet
• TA -09 - Temperature at altitude was -9°C
• TB MODT - Turbulence was moderate

A Cessna 172 pilot flying northeast of Memphis at 9,000 feet reported broken clouds below, minus-nine Celsius, and moderate turbulence. That is information you cannot get from a TAF or area forecast.

What Do the Turbulence and Icing Intensity Levels Mean?

Both turbulence and icing use standardized intensity scales that are worth memorizing.

Turbulence:

• Smooth - No turbulence
• Light - Slight, erratic changes in altitude or attitude
• Moderate - Changes that strain the aircraft structure or make walking difficult in the cabin
• Severe - Large, abrupt changes with the aircraft temporarily out of control
• Extreme - Forces so severe the aircraft may be structurally damaged

Icing:

• Trace - Barely perceptible accumulation
• Light - Accumulation that may become a problem if prolonged
• Moderate - Even short encounters can be hazardous
• Severe - Deicing or anti-icing equipment cannot control accumulation

Aircraft type is relevant context for turbulence reports. Moderate turbulence in a Boeing 767 means something different than moderate turbulence in a Cessna 172. The aircraft type entry helps calibrate intensity, but it’s not a perfect system - different pilots also have different thresholds for what they report.

What Is an Urgent PIREP and When Should I Stop and Read One?

An urgent PIREP (UUA) is filed when a pilot encounters conditions that pose an immediate hazard to other aircraft: severe turbulence, severe icing, a tornado, a waterspout, or wind shear that nearly took the aircraft out of the sky.

When you see a UUA in your briefing, read it carefully before continuing. The FAA and the National Weather Service use urgent PIREPs to update forecasts and AIRMETs in real time. They’re the mechanism by which actual in-flight conditions feed back into the forecast system.

Where Do I Find PIREPs During a Weather Briefing?

If you’re doing a standard weather briefing with a live briefer at 1800wxbrief, PIREPs relevant to your route and altitude are part of the standard briefing sequence - the briefer will read them to you.

If you’re self-briefing electronically, you have to go actively look for them.

• ForeFlight - Enable PIREP display on the weather map; they appear as color-coded symbols by type
• Garmin Pilot - Similar display to ForeFlight
• aviationweather.gov - Pull PIREPs directly, filter by area, view in plain text or decoded format

The habit to build: PIREPs belong in your standard preflight briefing, not as an afterthought after you’ve already decided to go.

What Are the Limitations of PIREPs I Need to Understand?

PIREPs are powerful, but using them well means understanding where they fall short.

Sparsity. On busy IFR routes between major airports, PIREP coverage may be reasonably dense. On a Tuesday morning at a lower altitude in the middle of the country, you may have almost nothing. Absence of PIREPs does not mean absence of significant weather - it means nobody filed a report.

Age. PIREPs age quickly. A report of smooth conditions at 6,000 feet from three hours ago doesn’t mean it’s smooth now. Most briefing services flag PIREP timestamps - pay attention to them.

Subjectivity. An experienced air carrier pilot with thousands of hours might report light turbulence that a lower-time private pilot would call moderate. Aircraft type gives context, but calibration varies by pilot.

Point observations. A PIREP reports conditions at one point, one altitude, one time. The atmosphere isn’t uniform. PIREPs are data points, not guarantees.

How Should PIREPs Change My Go/No-Go Decision?

Consider this scenario: you’re planning a flight over a mountain range. The forecast calls for light to moderate turbulence below 12,000 feet - a vague statement that covers a wide range of actual experience.

Now you pull PIREPs along your route from the past two hours:

• A Beechcraft Bonanza at 10,000 feet reports moderate chop with occasional severe jolts
• A Piper Archer at 8,000 feet reports the same
• A Cessna 172 at 9,500 feet reports severe turbulence and a 500-foot altitude loss before recovery

The forecast said light to moderate. Three PIREPs from different aircraft types, across a range of altitudes, within the last two hours are all saying severe. That is actionable information that changes the go/no-go calculation.

This is also what your examiner is looking for on a checkride. The Airman Certification Standards expect you to obtain and analyze weather - not just check an app. Walking an examiner through what PIREPs along your route were showing, and what that meant for your decision, demonstrates weather awareness that goes well beyond surface-level briefing.

How Do I File a PIREP in Flight?

When you encounter something significant - or even something routine that would be useful to someone following you - you have a professional obligation to report it.

Filing is simple. Contact ATC and say: "[Facility], [callsign], I have a PIREP." The controller will respond and take your report. Provide your location, altitude, aircraft type, and what you observed. They format it and push it into the system. The whole exchange takes about 60 seconds.

You don’t need severe conditions to file. A smooth ride above a cloud deck with tops at a specific altitude is valuable. Clear skies at altitude when the forecast called for obscuration is valuable. Benign condition reports help other pilots just as much as alarming ones do.

The PIREP system only works because pilots feed information into it. Consuming PIREPs without ever filing one lets the system go dry.

How Do PIREPs Fit Into a Complete Weather Briefing?

A practical briefing sequence that uses PIREPs effectively:

1. Surface analysis and prog charts - Understand the synoptic-scale pattern. Where are the fronts? Where is the high pressure?
2. Area forecast - Build a broad expectation of conditions for the region
3. METARs and TAFs - Ground-level snapshots and near-term forecasts at departure, destination, and en route airports
4. PIREPs - By this point you have a mental model of what conditions should be. PIREPs either confirm that model or challenge it

Look specifically for icing, turbulence, and cloud top information. If PIREPs paint a significantly different picture than the model, go back and look harder at the forecast products to understand why. Sometimes forecasts are simply behind actual conditions. Sometimes a mesoscale phenomenon wasn’t captured.

The goal is not to find data that lets you go. The goal is to build the most accurate picture of what you’re flying into, then make an honest decision.

AIM Chapter 7 covers the full PIREP encoding format, intensity scales for turbulence and icing, and filing procedures. The Aviation Weather Center at aviationweather.gov publishes guidance on interpreting PIREPs alongside other weather products. Both are worth reading through.

Key Takeaways

• A PIREP is an eyewitness account - the only product in your briefing that reports actual in-flight conditions rather than predicting them
• Urgent PIREPs (UUA) report immediate hazards and directly update AIRMETs and forecasts in real time
• Absence of PIREPs means absence of reports, not absence of weather - sparse coverage is itself meaningful context
• Multiple PIREPs showing conditions worse than forecast is actionable; one PIREP showing smooth conditions is a data point, not a guarantee
• Filing PIREPs is a professional obligation - the system is only as good as the pilots who feed it