Turbulence Reporting: How Rough Air Appears in Every Product

Turbulence reporting runs through four products, each with its own encoding, and they split at severity rather than at subject.

One ladder sits underneath all of them: light, moderate, severe, extreme. What changes between products is who is warned and how the warning is written.

The intensity ladder

The steps are defined by what the aircraft and the occupants do, not by a measurement. That is what makes them reportable by any pilot.

Light gives small ragged changes in height or attitude. People feel a slight pull against the belts. Loose items stay put.

Moderate changes the attitude or altitude, while the aircraft stays under control. Occupants feel definite strain against belts. Unsecured objects move about.

Severe gives large sharp changes, and the airspeed swings with them. For a moment the aircraft may not be under control.

Extreme means the aircraft is thrown about and cannot be controlled. It can be damaged.

Why the aircraft type sets the scale

This is the part most often skipped, and it changes the meaning of every report.

The definitions describe what happens to the aircraft. A light single and a heavy transport flying through identical air will not experience identical changes in attitude, so they will not report the same word.

Moderate from a Cessna 172 might be light chop in a 737. Moderate reported by a heavy jet describes air that would be alarming in a trainer.

That is why a PIREP carries the aircraft type in the /TP field, and why reading the intensity without it is close to meaningless.

PIREPs: what a pilot felt

The /TB field carries turbulence, and it packs three things into a few letters.

A frequency qualifier can come first: OCNL for occasional, INTMT for intermittent, CONS or CONT for continuous.

Then the intensity: LGT, MOD, SEV, EXTRM, or NEG and SMOOTH for nothing at all.

Then a type: CHOP for rhythmic bumpiness with no attitude change, CAT for clear-air turbulence, LLWS for low-level wind shear, MWAVE for mountain wave.

So /TB CONS LGT CHOP 350 is continuous light chop at flight level 350. Steady, mild, and not moving the aircraft off its path.

AIRMET Tango: the moderate forecast

Tango is the civil area forecast for turbulence, and it stops at moderate.

It also carries two related hazards from the same cause: sustained surface winds of 30 knots or more, and low-level wind shear that no thunderstorm produced.

Like every AIRMET it needs a wide area, so it describes the scale of the rough air rather than conditions at any one point. Inside a Tango there will be smooth patches, and outside one there can still be a rough ridge.

Because it stops at moderate, a Tango is never the worst case for the day.

SIGMETs: severe and above

Severe turbulence is a SIGMET. That is the line where a hazard stops troubling only some aircraft and starts troubling all of them.

An international SIGMET writes it as SEV TURB, with a level band, an area and a movement. SEV MTW marks severe mountain wave, which is turbulence tied to terrain and often extends far downwind of the ridge that caused it.

The level band is the line to read first. Many turbulence SIGMETs occupy a slab with smooth air above it, so the question is whether you can get on top.

Military TAFs: turbulence as a number

A military TAF encodes turbulence into the forecast itself, using the 5-group.

520005 reads as the turbulence group, code 2 for occasional moderate turbulence in clear air, based at the surface, 5000 feet thick.

The intensity digit follows a pattern. Codes 2 to 5 are moderate, 6 to 9 are severe. Odd numbers are frequent and even numbers are occasional. The first pair of each block is clear air and the second pair is in cloud.

Those values come from AFMAN 15-124 Table 1.7, read by our decoder as the table writes them.

Where the products disagree

The four do not always tell the same story, and the gaps are worth knowing.

An advisory covers six hours and thousands of square miles. A report covers one aircraft at one moment. They can differ without either being wrong.

The report is fresher, so weight it for the next hour. The advisory is broader, so weight it for the whole route.

There is one gap neither fills well. Wave and rotor near hills are patchy, so a wide area product smooths them over and a report only tells you about the line one aircraft flew.

Near terrain, treat both as optimistic.

Verdict on turbulence reporting

Learn the four-step ladder, then always read it next to the aircraft type. The words describe what happened to a specific aeroplane, not a property of the air.

Use Tango for the region and the expectation, SIGMETs for the severe end and for routing, and PIREPs for what the air actually did in the last hour. Where a report and an advisory disagree, the report is fresher, but it covers only the sky one aircraft passed through.

Last updated August 29, 2026