Long ago I was junior counsel to a large airline.
I travelled quite a bit but never once did I see an incident on board attributable to a passenger's seat belt being unfastened.
Funny thing, though, back at the office part of my daily work was to review reports (which you may be sure would be followed by claims for damages) of "in-flight incidents".
"Operations" copied me in on these in live time as and when received from the aircraft en route ..... medical emergencies, reports from physicians if one was on the passenger list, babies gone unconscious, passengers falling, scalds, choking, and of course "turbulence incidents", flying objects, bruises and claims of worse. No day passed without a crop from somewhere in the system, which ran from Los Angeles to Vienna, with North-South variations.
That is, even though I -- or you -- did not see them, someone did. They were routine spectatcles daily to stewards and stewardesses, as they were then known, somewhere in our business.
My practice in all flights was therefore to fasten the seat-belts, save when I was actually up and doing something.
The other determinant was my experience as a pilot when the vertical catches on the seat once became disconnected. At each little bump in turbulence I would shoot up to the top of the track with my bone-dome bumping off the canopy and the control column down by my ankles, or plunge into the bowels of the cockpit with the firing button opposite my nose, whence I would peer over the edge of the coaming. It was all the more exciting because I was in formation at the time. Not for long, though.
You have to experience unexpected unrestrained even modest +/- G-forces to appreciate just how unrestrained you really are.
I suggest you fasten the seat-belt.
P.S.
Years later I was with an airline that flew hard-rock miners into the Great North and out again after months of isolation. We flew DC-4s. We briefed lady cabin staff recruits were briefed that the lads had been away from the gentle refining influence of woman for some, perhaps many, months, and we recomended that they not fall in the aisles. If they absolutely could not avoid falling, we counselled, try not to fall on your back.
Last edited by Davaar; 21st Feb 2009 at 00:45.