Career Pilot: Turbulence reports

According to my company’s operations manual, which borrows nearly verbatim the language of the Aeronautical Information Manual, light turbulence is described as “slight bumpiness and/or momentary erratic changes in altitude/attitude:

“Drinks occasionally splash out of cup.

“Little or no difficulty in walking.

“Occupants may feel slight strain against seat belts.”

The manual describes moderate turbulence: “A harsher ride than light turbulence with changes in altitude and/or attitude, but the aircraft remains in positive control; typically causes variations in indicated airspeed:

“Drinks splash out of cup with consistency.

“Standing or walking is sometimes difficult or impossible without holding on to a part of the aircraft.

“Occupants feel definite strain against the seat belts.”

I always have a water cup next to me when I’m flying at work, and I typically use water splashing out of the cup as my primary indication of the type of turbulence to report. No drops of water around my cup holder equals light turbulence or less. On the flight into Denver, this was the case. In addition, my rear end was firmly planted in the seat, indicating that there was no “strain against seat belts” either.

However, my captain focused on the statement regarding difficulty walking, while keeping in mind our three flight attendants in the back and any passengers who might have been ignoring the illuminated seat belt sign. Sure, I get that. There’s no better way to get on the wrong side of your cabin crew than not knowing when to tell them to strap in for the rough ride. After all, those of us in the cockpit are always safely strapped into our seats, while our flight attendants are standing or walking in an attempt to secure galley equipment or check passenger seat belt compliance.

So is there a problem with the definitions, or a problem with pilot perceptions of turbulence? I’ve always been of the opinion that pilots tend to overstate turbulence. I understand that the invisible menace can be annoying and often more than a little unnerving when the bumps really get going. But I take evasive action when the airplane in front of me reports moderate or severe turbulence. ATC takes moderate to severe reports seriously, as well, so it is critical to report the conditions accurately. If the reported moderate doesn’t even meet two of the three criteria for light, then it becomes a classic boy-who-cried-wolf scenario.

So who’s right, the captain or me? In a way, both of us. This is where the definitions may need a little revision. Perhaps the definitions should be modified for passenger carriers, as opposed to cargo haulers or GA airplanes. After all, if the human occupants are unable to get out of their seats because of cabin size, such as in GA airplanes, and are always strapped in, the walking criteria are essentially eliminated. Or if there’s only cargo in the back, the lines regarding walking also don’t apply.

Most turbulence-related injuries involve flight attendants, and it’s a serious concern for passenger carriers in terms of both safety and liability. In this case, the captain’s assessment that it was not safe for flight attendants to move around in the cabin would classify our turbulence as moderate that day, despite meeting only one of the criteria. My assessment was made by the fact that the other two criteria for light turbulence—drinks splash out of cup and slight strain against seat belts—weren’t met.

In the interest of flight-attendant safety and to cover our rears, I think it would be best to consider moving the “walking” definition of moderate turbulence to the light category when it comes to passenger carriers. Interestingly, the walking criteria also appears in the definition for severe turbulence, which is defined as: “Turbulence with large, abrupt changes in altitude and/or attitude and the aircraft may be momentarily out of control; typically causes large variations in indicated airspeed:

“Unsecured items are tipped over or tossed about.

“Standing or walking is impossible without holding on to part of the aircraft.

“Occupants are forced violently against seat belts.”

Yes, severe turbulence is really bad, and crew action should be taken immediately to avoid it if an aircraft ahead has reported it—for the reasons stated previously. But if unsecured items are “tossed about,” wouldn’t that also apply to humans? Anyone standing or walking in severe turbulence as defined by the other two definitions is ripe for an injury. Perhaps it’s time for another look at how these terms are defined.

Pete Bedell is a pilot for a major airline andco-owner of a Beechcraft Baron and Cessna 172.