Definition
Turbulence that is similar to light turbulence but greater in 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. Occupants feel definite strain against seat belts and shoulder straps, and unsecured objects are dislodged. Food service and walking are difficult.
Plain English
A noticeably bumpy ride. The aircraft bounces and shifts more than in light chop, and you can feel yourself pulled hard against the seat belt, but the pilot still has full control. Loose items in the cabin will move around, and pouring coffee or walking down the aisle becomes impractical.
Context Anchor
Seen in weather briefings, pilot reports, and AIRMET Tango information when turbulence is expected or reported along a route.
Derivation
Moderate comes from a Latin word meaning to keep within bounds. Turbulence comes from a Latin word connected with disturbance or disorder. Together, the phrase points to disturbed air that is significant, but still within a controllable range for the aircraft.
Why Pilots Care
Affects route planning, altitude selection, passenger safety, and decisions about whether to continue or divert.
Grounding Statement
In moderate turbulence, the air is uneven enough to move the aircraft noticeably, but not so violently that normal control is lost.
Intuition Check
Do not read moderate as “not a big deal.” In FAA use, moderate turbulence means the aircraft may have real altitude or attitude changes, even though it remains controllable.
Example Sentence 1
Approaching the ridge line, we encountered moderate turbulence, so I slowed to maneuvering speed and asked the passengers to tighten their seat belts.
Example Sentence 2
After encountering moderate turbulence at cruise altitude, the crew requested a descent to smoother air.