Originally Posted by
lincolnjkc
These are the definitions I'm aware of (at least for lay people); are they the same as the AMS definitions? Or I suppose, for this thread, are they the same as what UA uses internally?
Light - Momentarily causes slight, erratic changes in altitude or attitude - Unsecure objects may be displaced slightly, food service easily continued. No difficulty walking.
Moderate - Changes in altitude and/or altitude. Aircraft remains in positive control; variations in indicated air speed. - Unsecured objects dislodged. Food service and walking difficult.
Severe - Large abrupt changes in altitude and/or attitude. Large variations in indicated airspeed. Aircraft may be momentarily out of control. - Food service and walking impossible.
Extreme - Aircraft violently tossed about and is practically impossible to control. May cause structural damage - Strong desire to land.
I've noticed FAs have a tendency to inflate the turbulence level -- I'm guessing to get more people to comply with their requests. In one case pre-pandemic the flight deck made a "moderate" turbulence PA which the FAs then followed up with their own "as you can tell we're experiencing severe turbulence"
These are the ones I use, and that are published in the AMS Glossary of Meteorology, referencing the FAA:
Light: Causes slight, erratic changes in
altitude and/or attitude, and rhythmic
bumpiness as occupants feel a slight strain against seat belts.
Moderate: Similar to light, but of greater intensity, with rapid bumps or jolts, and occupants feel a slight strain against seat belts.
Severe: Turbulence that causes large, abrupt changes in altitude and attitude, and large variations in
airspeed, with the aircraft temporarily out of control. Occupants are forced violently against their seat belts and objects are tossed about, with food service and walking impossible.
Extreme: The aircraft is tossed about so violently that it is practically impossible to control, and structural damage may occur.
In popular passenger terms:
Light -- Noticeable but not worrisome
Moderate -- Uncomfortable
Severe -- Screaming and crying
Extreme -- Praying