AIM ¶ 7-1-21 — Turbulence PIREPs
AIM 7-1-21: How to report turbulence PIREPs to ATC, including intensity classifications (light, moderate, severe, extreme) and required report elements.
In Plain English
When you hit turbulence, ATC and other pilots need to know — fast. AIM 7-1-21 urges pilots to report turbulence as soon as practicable so controllers can warn following traffic and forecasters can refine their products. This is a recommended practice, not an FAR mandate, but it's a core airmanship expectation.
A proper turbulence PIREP includes:
- Aircraft location
- Time of occurrence (UTC)
- Turbulence intensity (light, moderate, severe, extreme)
- Whether it occurred in or near clouds
- Altitude or flight level
- Type of aircraft
- Duration of the turbulence
Intensity is classified per Table 7-1-11 based on aircraft reaction and reaction inside the cabin:
- Light — slight, erratic changes; occupants feel slight strain
- Moderate — greater intensity but aircraft remains in positive control; unsecured objects dislodged
- Severe — large, abrupt changes; aircraft momentarily out of control
- Extreme — aircraft violently tossed; possible structural damage
Use occasional (<1/3 of the time), intermittent (1/3–2/3), or continuous (>2/3) to describe duration. Above 15,000 ft and not associated with cumuliform clouds, report as CAT (clear air turbulence) with the appropriate intensity, or as light/moderate chop.
AIM Source Text
FAA AIM ¶ 7-1-217-1-21. 7-1-21. PIREPs Relating to Turbulence
When encountering turbulence, pilots are urgently requested to report such conditions to ATC as soon as practicable. PIREPs relating to turbulence should state: Aircraft location. Time of occurrence in UTC. Turbulence intensity. Whether the turbulence occurred in or near clouds. Aircraft altitude or flight level. Type of aircraft. Duration of turbulence. EXAMPLE- Over Omaha, 1232Z, moderate turbulence in clouds at Flight Level three one zero, Boeing 707. From five zero miles south of Albuquerque to three zero miles north of Phoenix, 1250Z, occasional moderate chop at Flight Level three three zero, DC8. Duration and classification of intensity should be made using TBL 7-1-11 . TBL 7-1-11 Turbulence Reporting Criteria Table Intensity Aircraft Reaction Reaction Inside Aircraft Reporting Term-Definition Light Turbulence that momentarily causes slight, erratic changes in altitude and/or attitude (pitch, roll, yaw). Report as Light Turbulence; or Turbulence that causes slight, rapid and somewhat rhythmic bumpiness without appreciable changes in altitude or attitude. Report as Light Chop. Occupants may feel a slight strain against seat belts or shoulder straps. Unsecured objects may be displaced slightly. Food service may be conducted and little or no difficulty is encountered in walking. Occasional-Less than / 3 of the time. Intermittent-/ 3 to / 3. Continuous-More than / 3. Moderate Turbulence that is similar to Light Turbulence but of greater intensity. Changes in altitude and/or attitude occur but the aircraft remains in positive control at all times. It usually causes variations in indicated airspeed. Report as Moderate Turbulence; or Turbulence that is similar to Light Chop but of greater intensity. It causes rapid bumps or jolts without appreciable changes in aircraft altitude or attitude. Report as Moderate Chop. Occupants feel definite strains against seat belts or shoulder straps. Unsecured objects are dislodged. Food service and walking are difficult. NOTE 1. Pilots should report location(s), time (UTC), intensity, whether in or near clouds, altitude, type of aircraft and, when applicable, duration of turbulence. 2. Duration may be based on time between two locations or over a single location. All locations should be readily identifiable. Severe Turbulence that causes large, abrupt changes in altitude and/or attitude. It usually causes large variations in indicated airspeed. Aircraft may be momentarily out of control. Report as Severe Turbulence. Occupants are forced violently against seat belts or shoulder straps. Unsecured objects are tossed about. Food Service and walking are impossible. EXAMPLES: a. Over Omaha. 1232Z, Moderate Turbulence, in cloud, Flight Level 310, B707. Extreme Turbulence in which the aircraft is violently tossed about and is practically impossible to control. It may cause structural damage. Report as Extreme Turbulence. b. From 50 miles south of Albuquerque to 30 miles north of Phoenix, 1210Z to 1250Z, occasional Moderate Chop, Flight Level 330, DC8. High level turbulence (normally above 15,000 feet ASL) not associated with cumuliform cloudiness, including thunderstorms, should be reported as CAT (clear air turbulence) preceded by the appropriate intensity, or light or moderate chop.
Oral Exam Questions a DPE Might Ask
Q1What information should be included in a turbulence PIREP?
Per AIM 7-1-21, a turbulence PIREP should include aircraft location, time of occurrence in UTC, turbulence intensity, whether it occurred in or near clouds, aircraft altitude or flight level, type of aircraft, and duration of the turbulence.
Q2How is the intensity of turbulence classified, and what's the difference between moderate turbulence and severe turbulence?
Per AIM 7-1-21 and Table 7-1-11, intensity is classified as light, moderate, severe, or extreme. Moderate turbulence causes changes in altitude/attitude but the aircraft remains in positive control; severe turbulence causes large, abrupt changes and the aircraft may be momentarily out of control, with occupants forced violently against seat belts.
Q3How should high-level turbulence not associated with cumuliform clouds be reported?
Per AIM 7-1-21, high-level turbulence — normally above 15,000 feet ASL — that is not associated with cumuliform cloudiness, including thunderstorms, should be reported as CAT (clear air turbulence) preceded by the appropriate intensity, or as light or moderate chop.
Related Paragraphs in AIM Chapter 7