Turbulence is officially categorized into four intensity levels based on its effect on the aircraft and occupants: Aircraft Reaction Occupant/Cabin Effect Slight, erratic changes in altitude or attitude. Slight strain against seat belts; liquids may splash. Moderate More intense changes; aircraft remains in positive control. Definite strain against belts; unsecured objects dislodge. Severe Large, abrupt changes; momentary loss of control.
Occupants forced violently against belts; walking is impossible. turbulence
Aircraft is tossed violently; practically impossible to control. Potential for structural damage to the airframe. Reports must also specify how often the bumps occur: Occasional: Less than 1/3 of the time. Intermittent: 1/3 to 2/3 of the time. Continuous: More than 2/3 of the time. 4. Common Types of Turbulence unsecured objects dislodge. Severe Large