View Full Version : Inertia reel seat belts

28th Jun 2004, 03:05
A recent posting on the general topic of seat belts / getting pax to use them made me think this: why aren't inertia reel belts fitted in a/c? Then it would be much more convenient for passengers to wear them all the time. Perhaps one of the "proper" users of PPrune could comment on this.

28th Jun 2004, 10:34
I would have thought that "time to lock" would be the problem here. Give a car seat belt a good hard yank, and see how much belt pays out from the reel before the reel locks.

With the current hard-fastened buckle system, seat belts stretch by up to 10% of their length in restraining the pax - one of two good reasons to make sure that when your belt is fastened for take off and landing, it is done up tight.

If you add to that much inherent "slack" in an emergency system the additional amount that would pay out from an inertia reel, you would be seriously eroding the safety margin.

28th Jun 2004, 12:24
Scot Airways Dornier 328s have 3-point inertia reel belts, lap strap and shoulder harness. They're the only commercial aircraft I have seen them on but they come over as much more professional than the lap-only belts (which were the standard fitting in US cars in the 1960s, but UK authorities wouldn't allow them).

Any other aircraft with such belts in passenger seats ? 3 point belts are standard in light aircraft, but no inertia reels, just lots of fiddling at the start !

28th Jun 2004, 19:13
The company I work for, operates 7 helicopters. 5 have standard lap belts for the pax, and 2 have inertia reel belts.
On average, we probably have 8-10 times more faults with the inertia belts, as there is very little that can go wrong with standard lap belts.
If on a large aircraft with 200-300 seats, this failure rate occured, I could see there being a lot more delayed flights.

29th Jun 2004, 00:48
Remembering that they work on a centrifugal weight system (for the fast pull) AND a tilt reactive device (for the out of limits angle lock) I think there may be some issue with the things locking constantly and no belt being able to be spooled out due to bank/climb angles and g-forces effecting the internal weights.

This may of course create a situation where the pax who has left their seat and returns as turbulence begins may not be able to spool out the belt in order to fasten it due to the a/c attitude.:uhoh:

Not an ideal situation if the turbulence is moderate and worsening!
Viscious circle, the worse it gets the less chance of getting the belt out and on!! Flying pax!

Smart move, just keep the static belt on ALL the time anyway. Dont cut yourself in half with it in the cruise, it just being there will keep the ceiling away from your head in unexpected turbulence.
Besides how much can you move in the average tiny a/c seat anyway, probably less than a tight static belt allows!;) :ok: