Updated: Feb 16
The FAA’s new wording on clear air turbulence...
CAT is defined as “sudden severe turbulence occurring in cloudless regions that causes violent buffeting of aircraft.”
This definition from a recent circular implies that it rarely exists because it is now only deemed violent. Thus, when I fly to London, Heathrow tonight that light perhaps moderate chop/turbulence is no longer labelled CAT. I admit, Clear Air Turbulence is a misnomer because many, including the FAA’s definition, denotes it as only occurring in cloudless regions. We in Canada have a huge coast to coast chain store called Canadian Tire, but they sell more than tires. In fact, tire sales are probably less than 5%.
Cloudless sky? Sometimes, but certainly not all the time!
Clear Air Turbulence occurs in a Mackerel sky. That’s those high based cirrocumulus clouds roughed up by a jet stream that take on the appearance of fish scales. Then there is turbulence near jet stream cirrus and the back and north side of a developed low pressure called the deformation zone. It’s the top portion on the infamous comma cloud seen on satellite pictures I talk about in my books. CAT can also occur is thin wispy cirrus.
This nouveau FAA definition had me so rattled I contacted them. They did get back to me and stated they are rostering up some meteorologists to discuss things with me. Still waiting.
I noticed this bizarre definition made it into my companies FOM (Flight Operations Manual). Basically, it is a “cut and paste” job with few understanding this meteorological voodoo.
I like how Transport Canada acknowledges CAT (well at least they acknowledge light and moderate). CAT remains a problem for flight operations, particularly above 15 000 ft. The best information available on this phenomenon is still obtained from PIREPs, since a CAT forecast is generalized and covers large areas. All pilots encountering CAT conditions are requested to urgently report the time, location, flight level and intensity (light, moderate, severe, or extreme) of the phenomena to the facility with which they are maintaining radio contact. I talked to TC's meteorologist and he basically insinuated BIG brother does whatever they want so he ain't rattling their chain. I will!
To all you airline pilots or high altitude flyers...those light to moderate bumps you encounter is no longer CAT. You must be in severe turbulence with violent buffeting making you a scaredy cat in CAT.