An atmospheric phenomenon that causes changes in aircraft altitude, attitude, and/or airspeed with aircraft reaction depending on intensity. Pilots report turbulence intensity according to the aircraft’s reaction as follows:

1. Light- Causes slight, erratic changes in altitude and/or attitude (pitch, roll, or yaw).
2. Moderate- Similar to Light 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.
3. Severe- Causes large, abrupt changes in altitude and/or attitude. It usually causes large variations in indicated airspeed. Aircraft may be momentarily out of control.
4. Extreme- The aircraft is violently tossed about and is practically impossible to control. It may cause structural damage.

Source FAA Pilot/Controller Glossary↗ · checked 2026-08-25