The PIREP, the Weather Report Made by Pilots for Pilots, and How to Read and File One From the Cockpit

A PIREP (pilot report) is the only aviation weather product created by a human pilot who is actually airborne in the conditions, reporting in real time what the atmosphere is doing to an aircraft. Unlike forecasts, METARs, or radar - which observe the sky from the outside - a PIREP delivers ground truth on turbulence, icing, cloud tops, and visibility at a specific location and altitude. Reading and filing them is one of the highest-value, lowest-difficulty skills a pilot can build.

Why Is a PIREP More Valuable Than a Forecast?

Almost all aviation weather is either a forecast or a machine reading. The TAF is a professional’s best guess about the future. The METAR reports what the sky is doing at one point on the ground. Winds aloft come from computer models, and radar sees precipitation - not turbulence, not ice, not the actual ride.

Every one of those tools looks at the atmosphere from the outside. A PIREP comes from inside it.

The forecast tells you what might happen. The PIREP tells you what is happening. That difference is the gap between “icing is possible” and a Cessna 172 pilot who just picked up a quarter inch of clear ice in ten minutes at 6,000 feet over the ridge you’re about to cross.

What’s the Difference Between a UA and a UUA?

A pilot report follows a standard format, and once you recognize the pattern, it decodes itself every time. There are two types:

• UA - a routine pilot report.
• UUA - an urgent pilot report.

When you see that second U, pay attention. Urgent reports are reserved for things that hurt airplanes: severe turbulence, severe icing, hail, low-level wind shear, funnel clouds, and volcanic ash. If Flight Service tagged a report urgent, someone up there had a bad enough moment to make sure you didn’t repeat it.

How Do You Read a PIREP? Decoding Each Field

The report is built from fields, each with a letter code. Here’s what each one tells you.

/OV (“over”) - Location. Given relative to a VOR: an identifier, a three-digit radial, and a distance. It’s a bearing and range from a known fixed point - the atmosphere’s home address. A PIREP 40 miles off your route on the far side of a mountain range may mean nothing; one sitting on your line of flight means everything.

/TM (“time”) - Time in Zulu. How old is this report? A turbulence report from three hours ago is a history lesson. One from six minutes ago is a warning. Always check the time.

/FL (“flight level”) - Altitude in hundreds of feet. A flight level of 065 means 6,500 feet. Turbulence and icing are intensely altitude-dependent, so this field is critical. A smooth ride reported at 9,000 does you no good if you’re crossing at 4,500 where terrain-driven mechanical turbulence is beating everyone up.

/TP - Type of aircraft. The airplane changes the whole meaning of the report. Moderate turbulence in a Boeing 737 will be genuinely violent in a Piper. Light chop called out by a Cub pilot might barely register in a King Air. Always ask: what was he flying, and how does my airplane compare?

/SK - Sky cover. The cloud layers, tops, and bases the pilot saw with his own eyes. No ground instrument on Earth can tell you the tops of a layer - only a pilot climbing through it can say, “I broke out on top at 7,200.” For a VFR pilot staying clear or an IFR pilot climbing into smooth air, a tops report is information you can’t get anywhere else.

/WX - Weather. Flight visibility, precipitation, and restrictions to vision.

/TA - Temperature in Celsius. It matters more than you’d think: temperature plus visible moisture is your icing recipe.

/WV - Wind. Direction and speed at altitude - the real winds, not the modeled ones.

/TB - Turbulence and /IC - Icing. These are why most PIREPs exist, and they deserve their own breakdown.

What Do the Turbulence Intensity Terms Actually Mean?

These are defined terms, not casual adjectives:

• Light - Slight, erratic bumpiness. Occupants may feel a slight strain against the seat belt.
• Moderate - More intense changes in altitude and attitude, but the pilot stays in control. Unsecured objects move around. That coffee is now on the ceiling.
• Severe - Large, abrupt changes in altitude and attitude. The aircraft may be momentarily out of control.
• Extreme - The aircraft is violently tossed and practically impossible to control, with possible structural damage. Almost none of us will ever see it and live to file it.

Reports also carry a modifier for chop (rhythmic bumpiness) versus the kind that throws you around, plus a frequency: occasional, intermittent, or continuous.

Here’s the practical takeaway. When you see moderate turbulence reported by an airplane your size or smaller, on your route, at your altitude, filed 20 minutes ago, you’ve been handed a decision to make before you ever leave the ground - different altitude, different route, or different day. That’s not timidity. That’s the entire point of the report.

How Do You Interpret Icing Reports?

Icing terms trip people up, so learn them cold:

• Trace - Barely perceptible; ice accumulates slower than it sublimates.
• Light - A problem only if you stay in it over an hour; occasional deice use or a heading change handles it.
• Moderate - Even short encounters become potentially hazardous. Change something now.
• Severe - The deice equipment can’t keep up. Get out immediately, because ice is accumulating faster than anything you can do about it.

Icing type matters too. Rime ice is the milky, rough stuff. Clear ice is the smooth, heavy, hard-to-see glaze that forms from larger droplets - and it’s the truly dangerous one. A PIREP reporting moderate clear ice should raise the hair on your neck, especially in a light airplane with no ice protection, which describes most of us.

How Do I File a PIREP From the Cockpit?

Filing a PIREP is one of the easiest and most useful radio calls you’ll ever make, and the weather system depends on ordinary pilots doing it. Here’s who to tell:

• A controller you’re already talking to, if they’re not too busy - they’ll relay it.
• Flight following - that’s your person.
• Flight Service on a published frequency (122.2 is a common one) when you’re out of range of a facility. Say the facility name, your call sign, and that you have a PIREP.

The best part: you don’t have to speak in code. You never say “slash TB.” You just talk, and the specialist or controller fills in the fields for you.

Key the mic and say something like: “Position, altitude, aircraft type - I’m getting moderate turbulence, continuous, and the tops are at 7,500.” That’s a complete, useful, potentially lifesaving PIREP. You gave them the where, the how high, the what, and the weather. Thirty seconds later it’s on a screen in front of the pilot behind you.

Should You File a PIREP When Conditions Are Good?

Yes - file the good news too. We’re great at reporting bumps and ice, but “smooth ride, tops at 6,000, clear on top” is just as valuable.

A pilot on the ground staring at a gloomy forecast might make a completely different and safer decision because you told him it was beautiful above a thin layer. Negative PIREPs - reports that conditions are better than forecast - are among the most useful in the system, and almost nobody files them.

How Do PIREPs Fit Into Your Checkride and Real-World Planning?

On your checkride cross-country planning scenario, the Airman Certification Standards (ACS) expect you to know your weather sources and interpret them. A candidate who pulls the PIREPs, decodes them out loud, and says, “there’s a moderate ice report at my planned altitude from 40 minutes ago, so I’ll plan lower or wait,” is demonstrating exactly the aeronautical decision-making and risk management the examiner wants.

In real flying, don’t just skim METARs and TAFs. Specifically pull the PIREPs for your route and altitude, then ask three questions:

1. How old is it?
2. What was he flying compared to me?
3. Is it at my altitude and on my line of flight?

If the answers line up and the report is telling you something bad, believe it. It’s the one report in the stack that came from an airplane, not a model.

A Scenario That Makes It Stick

You’re planning a cross-country next Saturday morning. The forecast is marginal, with an AIRMET for occasional moderate icing above a freezing level the models put at about 5,000 feet. In an airplane with no ice protection, that feels like a no-go.

But you pull the PIREPs and find three reports from that morning along your route - two Cessnas and a Bonanza. All three report negative icing at 6,000 and 7,000 feet, smooth on top, with tops at 5,500. Suddenly you have real information: the ice the model warned about isn’t materializing where pilots are actually flying.

That doesn’t automatically make it a go - conditions change, and a two-hour-old report is no guarantee. But you’re no longer deciding blind. You’ve replaced a computer’s worry with three human beings’ ground truth.

The flip side is just as true. If those same three reports had said light to moderate rime at 6,000, you’d have every reason to stay on the ground and feel good about it, because three pilots just confirmed the forecast was right.

The intensity definitions come straight from the FAA’s guidance on pilot reports and the standard weather product definitions from the Aviation Weather Center; the decision-making framework lives in the Airman Certification Standards. Read the intensity definitions for yourself - they’re worth knowing cold.

Key Takeaways

• A PIREP is the only weather report made by a pilot actually flying in the conditions, making it real-time ground truth rather than a forecast or model.
• Decode the core fields - location (/OV), time (/TM), flight level (/FL), aircraft type (/TP), turbulence (/TB), and icing (/IC) - and always weigh the report against your own aircraft, altitude, and route.
• Learn the defined turbulence and icing intensity terms; a moderate report from an aircraft your size on your route is a decision point before you take off.
• You can file a PIREP in plain English - just report position, altitude, aircraft type, and what the sky is doing; the controller or Flight Service formats it.
• File the good news too. Negative PIREPs help other pilots make safer go/no-go decisions and are badly underreported.