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AIM

10/12/17

7−1−45

Meteorology

7−1−23. PIREPs Relating to Turbulence

a. When encountering turbulence, pilots are

urgently requested to report such conditions to ATC

as soon as practicable. PIREPs relating to turbulence

should state:

1. Aircraft location.
2. Time of occurrence in UTC.
3. Turbulence intensity.
4. Whether the turbulence occurred in or near

clouds.

5. Aircraft altitude or flight level.
6. Type of aircraft.
7. Duration of turbulence.

EXAMPLE−
1. Over Omaha, 1232Z, moderate turbulence in clouds at
Flight Level three one zero, Boeing 707.
2. 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.

b. Duration and classification of intensity should

be made using TBL 7−1−10.

TBL 7−1−10

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; 

1

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 con-

ducted and little or no difficulty is

encountered in walking.

Occasional−Less than 

1

/

of the time.

Intermittent−

1

/

to

 2

/

3.

Continuous−More than 

2

/

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; 

1

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.

1

Occupants feel definite strains against

seat belts or shoulder straps. Unse-

cured 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. 

1

Occupants are forced violently against

seat belts or shoulder straps. Unse-

cured 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.

 1

b. From 50 miles south of Albuquer-

que to 30 miles north of Phoenix,

1210Z to 1250Z, occasional Moderate

Chop, Flight Level 330, DC8.

1

 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.