Definition
An intensity descriptor used in pilot turbulence and icing reports indicating conditions stronger than Light but not yet Severe. For turbulence, Moderate produces changes in altitude and/or attitude, but the aircraft remains in positive control at all times; occupants feel definite strain against seat belts and unsecured objects are dislodged. For icing, Moderate means the rate of accumulation is such that even short encounters become potentially hazardous and use of de-icing/anti-icing equipment or a flight path change is necessary.
Plain English
It is the same kind of bumpiness or ice build-up as Light, just noticeably stronger. The aircraft is still flying normally and you are still in control, but you really feel it, things shift around in the cabin, and you usually need to do something about it.
Context Anchor
Seen in turbulence reports, pilot reports, weather briefings, and forecast discussions.
Derivation
From Latin moderatus, meaning 'kept within measure' or 'restrained.' In aviation reporting, it sits in the middle of a four-step intensity scale (Light, Moderate, Severe, Extreme), keeping the meaning of 'in between' intact.
Why Pilots Care
Moderate turbulence can cause passenger discomfort, spilled drinks, and minor injuries if unsecured; pilots must decide whether to change altitude or reroute.
Grounding Statement
Moderate turbulence may bump the aircraft enough to change its altitude or nose position, but it does not take control away from the pilot.
Intuition Check
Moderate does not mean “minor” or “nothing to worry about.” In turbulence reports, it means stronger than light turbulence, but not so strong that the aircraft is out of control.
Example Sentence 1
The pilot reported moderate turbulence at 8,000 feet, and ATC relayed the report to other aircraft on the route.
Example Sentence 2
The area forecast warned of moderate turbulence below 12000 feet after the cold front passes.