The Pirep, the Pilot Weather Report That Only Other Pilots Can Give You, and Why Filing One Is the Civic Duty Nobody Talks About in Ground School

A pilot weather report (PIREP) is the only element of your preflight briefing that gives you a live, eyeball account of atmospheric conditions from an actual pilot in flight. Everything else is either historical (METARs) or predictive (TAFs). An empty PIREP map does not mean clear skies - it means no one has reported yet, and that distinction has real operational consequences.

What Is a PIREP and How Does It Differ from Other Weather Products?

A PIREP - abbreviated from “pilot weather report” and pronounced exactly as it looks - is a real-time observation submitted by a pilot in flight. It is not a forecast and not a model output.

This matters because METARs snapshot conditions at airports, TAFs predict terminal conditions, and AIRMETs/SIGMETs mark large-scale hazards. PIREPs fill the space between all of those fixed data points. They are the connective tissue of your weather picture - the part of the briefing that tells you what the atmosphere is actually doing between the stations and between the models.

The National Weather Service relies on them, air traffic control passes them along, and Flight Service Stations push them into the system when pilots call them in over the radio. When you pull up your electronic flight bag or call 1-800-WX-BRIEF, PIREPs from pilots ahead of you on the route appear alongside your other weather products.

What Are the Two Types of PIREPs?

Routine PIREPs are designated UA. These cover the full range of observations a pilot might make - sky condition, turbulence, icing, temperature, visibility - during normal flight.

Urgent PIREPs are designated UUA. The urgent classification is reserved for conditions significantly worse than forecast: severe turbulence, severe icing, tornadoes or waterspouts, volcanic ash, or hail. A UUA moves through the system faster and receives special handling. You may hear one read over an ATIS broadcast, passed by a controller during flight following, or called out by a Flight Service briefer.

Most of what you encounter in a standard briefing will be routine UAs.

How Do I Read a PIREP?

PIREPs look like a wall of abbreviations on first encounter. Each field is separated by a slash, and most fields are optional - a pilot files only what they actually observed. The required fields are location, time, and aircraft type. Everything else depends on what conditions exist.

Here is a sample PIREP decoded field by field:

UA /OV BGR /TM 1530 /FL080 /TP C172 /SK BKN060 /TA -22 /WX FV03 /TB LGT /IC NEG /RM FOGLY RS BLW

• UA - Routine pilot report
• OV BGR - Over Bangor, Maine (three-letter identifier)
• TM 1530 - Filed at 1530 Zulu
• FL080 - Flight level 080, or 8,000 feet
• TP C172 - Aircraft type: Cessna 172
• SK BKN060 - Sky condition: broken at 6,000 feet
• TA -22 - Temperature: -22°C at 8,000 feet
• WX FV03 - Forward visibility: 3 statute miles
• TB LGT - Turbulence: light
• IC NEG - Icing: none reported
• RM FOGLY RS BLW - Remarks: foggy layers below

Once you learn the field codes, you stop reading abbreviations and start reading a pilot’s actual experience at altitude. That changes your relationship with the information.

A PIREP that only contains a turbulence entry and a flight level is still useful. It still tells you something real happened at that location and altitude.

How Do I Interpret the Turbulence Intensity Scale?

The turbulence intensity scale runs from smooth to extreme, and the practical differences between levels matter for your decision-making.

• Negative (NEG) - None reported
• Light - Bumpiness, but you can manage documents and drinks without incident
• Light chop - Rhythmic bumpiness without significant altitude changes
• Moderate - Unsecured objects move in the cabin; you are working to hold altitude and heading; avoid instrument approaches or maneuvering flight if possible
• Severe - Abrupt changes you cannot fully control; occupants thrown against restraints
• Extreme - Rare; aircraft momentarily beyond control

Most general aviation PIREPs report light or light-chop conditions. A moderate turbulence report at an altitude similar to your planned cruise altitude is a signal to slow to maneuvering speed before you reach that area. A severe report warrants a route or altitude change and a call to Flight Service to determine whether conditions are building or dissipating.

How Do I Interpret Icing Reports?

Icing PIREPs carry two components: intensity and type.

Intensity levels:

• Trace - Minimal accumulation, no real performance effect in short exposures
• Light - Slight performance reduction, manageable
• Moderate - Ice protection systems must be active, or exit the conditions
• Severe - Ice accumulating faster than it can be shed; this is an emergency-level event

Ice types:

• Rime - Forms when small supercooled droplets freeze instantly on contact; white, opaque, builds on leading edges
• Clear (glaze) - Larger droplets spread across the surface before freezing; denser, harder to remove, causes greater lift degradation
• Mixed - Combination of the above, most common in variable moisture environments

If your aircraft is not certified for known icing, a PIREP showing icing along your route at your planned altitude is not a yellow flag. It is a stop sign.

Where Do I Find PIREPs in My Preflight Briefing?

PIREPs are accessible through several sources, and using more than one gives you better coverage.

ForeFlight and Garmin Pilot both include a dedicated PIREP layer on the map. Tap any report to get a plain-language decoded version. The Aviation Weather Center at aviationweather.gov has a PIREP plotting tool where you enter your route and see all filed reports in the area. When you call Flight Service for a standard briefing, relevant PIREPs are included by default alongside AIRMETs and METARs.

How Old Is Too Old? Understanding PIREP Timestamps

A PIREP is perishable. The atmosphere moves. A report filed four hours ago over a mountain range may be completely irrelevant to current conditions.

The most actionable PIREPs are those filed within the last hour. Anything beyond 90 minutes - particularly in a dynamic weather situation - is background context, not current intelligence. Read it, note it, but do not treat a four-hour-old report as if the pilot just landed.

Also filter by altitude. A turbulence report at FL240 tells you very little about conditions at 3,500 feet in a Cessna 172. When evaluating PIREPs for your flight, focus on reports within your planned altitude band.

How Do PIREPs Fit Into a Complete Weather Briefing?

Think of your preflight briefing as building a three-dimensional picture of the atmosphere along your route. Each product contributes a different layer:

• METARs - Surface snapshots at airports
• TAFs - Terminal forecasts
• AIRMETs/SIGMETs - Large-scale hazards
• Winds aloft - Upper-air analysis
• PIREPs - Real-time conditions between all of the above

Use PIREPs to confirm the forecast was accurate. Use them to catch where it was wrong. A blank PIREP page is not a green light - it is an incomplete picture. Build your go/no-go decision accordingly.

A practical scenario: You are planning a cross-country into the upper Midwest. The TAF at your destination shows broken clouds at 4,000 feet, tops unknown. An AIRMET Sierra covers mountain obscuration near the destination. On the surface, the route looks workable.

Then you find a PIREP: a Piper Archer filed moderate mixed icing at 6,000 feet, 40 miles from your destination, temperature -8°C, filed 40 minutes ago.

You are flying a Cessna 172 with no known icing certification. That single report tells you the freezing level is low, moisture exists above 4,000 feet, and an aircraft in the same general category as yours found conditions you cannot legally or safely fly in. You are now making a decision with information instead of guessing into a blank page. You call Flight Service, check alternates, look for whether a lower altitude keeps you below the freezing level. One PIREP changed the entire shape of your planning.

How Do I File a PIREP?

The system only works because pilots contribute to it. There is a chronic shortage of reports at general aviation altitudes, particularly in lower-traffic areas. Airline routes have reasonable coverage. Rural stretches of the Midwest or mountain west between busy corridors often do not. Someone departing that route an hour after you is looking at your blank page.

Filing is straightforward through any of these methods:

On flight following: Tell your controller you’d like to file a PIREP. They walk you through it - location, altitude, aircraft type, sky condition, temperature, turbulence, icing, remarks. You give plain-language answers; they handle the format.

Not on flight following: Contact Flight Service on 122.2. Same process.

Electronic flight bag apps: ForeFlight has a built-in PIREP form that prompts you through each field and submits automatically. No radio call required, no need to know the abbreviation format.

You do not need to have encountered dramatic conditions to file. Smooth air, scattered clouds, good visibility, no icing at 6,000 feet - that is useful information. It confirms the forecast matched reality. A report of nothing abnormal is still a data point, and it still helps the pilot behind you.

The Airman Certification Standards include PIREPs explicitly under the preflight assessment task. Expect an examiner to hand you a decoded PIREP and ask what it means for your route. This is tested material.

Make filing part of your shutdown checklist on every cross-country. You are contributing to the same system that gave you the reports that shaped your decision this morning.

Key Takeaways

• PIREPs are the only real-time weather product in your briefing - everything else is historical or predictive
• An empty PIREP map means no one has reported yet, not that conditions are clear
• Filter PIREPs by timestamp (prioritize reports under 60 minutes) and altitude band (focus on your planned cruise altitude)
• Moderate icing in a PIREP is a hard stop if your aircraft is not certified for known icing
• Filing a PIREP on every cross-country - even when conditions are uneventful - is how the system stays useful for everyone