Why are airplane seatbelts different from car seatbelts?

March 13, 2009 8:20 AM

Why are airplane seatbelts different from car seatbelts?

It seems odd that we would have these two totally different designs for seatbelts. If the airplane one is better (safer, easier to unlatch in a hurry, whatever), why don't we use them in cars? If not, why do we use a design that has to be explained to people? Is there something about the two designs that makes one better in a plane and the other better in a car?

posted by gleuschk to travel & transportation (14 answers total)

Cars most often hit things frontally, hence the shoulder strap. Planes tend to jerk around in three dimensions, hence the need to focus on keeping someone strapped to their seat.
posted by General Malaise at 8:25 AM on March 13, 2009

I would think it would have to do with the physics of how cars would crash versus the turbulance one might experience on a plane. (If you're in a plane crash, a seatbelt isn't going to be a great help, I don't think.)
posted by roomthreeseventeen at 8:25 AM on March 13, 2009

You're asking about the buckle, rather than the belt per se, right?
posted by box at 8:26 AM on March 13, 2009

Sorry, I should have been more specific: why are the buckle mechanisms different?

You're both right, of course, about the different needs for shoulder restraint etc.
posted by gleuschk at 8:27 AM on March 13, 2009

The flight attendants get extra money every time they explain to you how to fasten and unfasten the seatbelt. If the belts were just like the ones on cars, no explanation would be necessary, and the flight attendants would all quit. Thus, they make them differently...

Seriously though, this thread will tell you more than you ever wanted to know about airplane seatbelts.
posted by zachlipton at 8:27 AM on March 13, 2009 [1 favorite]

Car seatbelts used to be the same as airplane seatbelts, at least in my '73 International Travelall. I think that the problem is that the mechanism on those seat belts tends to wear out very quickly (especially after those interial, tensioned belt reels were introduced), it becomes a safety hazard, and after a few years the whole buckle mechanism needs to be replaced. On an airplane that's no problem - the maintenance schedule on any part of an airplane is relatively short. For a car, it makes more sense to sacrifice the few seconds it takes to unbuckle the belt/slice through the webbing for added security in the buckle latch.

I can't count the number of times I was driving around in that Travelall and discovered, incidentally, that the buckle had come undone.
posted by muddgirl at 8:37 AM on March 13, 2009

A fairly recent BBC program on how to survive air crashes included an interview with Professor Helen Muir at Cranfield University - she is a specialist on passenger behaviour following air crashes. I believe it was she who remarked on the number of people who die because, after a crash landing, they panic and try to open their seat belts as they would do on a car.

So there is definitely a potential down-side to the difference. Her page lists a number of publications if you wanted to dig further.

I believe I can remember car seat belts from the early 1970s which opened in the same manner as today's plane ones. Does anybody else?
posted by rongorongo at 8:53 AM on March 13, 2009 [2 favorites]

Just to add more confusion to the mix. I'm a helicopter flight instructor, and the helicopter seat belt is a cross between a car and a plane, but somewhat different.
Helicopter seat belts (when able, i.e. not a middle seat) have a 3 point (or more) restraint system (like a car) but often have a latch similar to a plane with the exception that the latch release must be lifted more than 90 degrees to release the seat belt from the latch.
Helicopter restraint systems with more than three points, tend to use a central latch/buckle (centered about the chest) like a race car.
posted by blackout at 9:03 AM on March 13, 2009

The three point belt like cars have now is significantly better at preventing facial and chest injuries (steering wheel/dashboard) than a simple waist belt - which is one reason you're advised to bend over and brace prior to crash in airplanes. Bracing is not quite as practical for car-drivers prior to impact. It's hard to do a three-point belt without putting it to the side, rather than the middle.

Aircraft belts with the centre buckle are easier to access and release, especially for someone helping the beltee, but as rongorongo points out, unfamiliarity with them can actually make them harder to get out of under stress.
posted by ArkhanJG at 9:43 AM on March 13, 2009

And a little more confusion. The passenger seats in a C.O.D. face backwards and have a full five point harness like a race car.
posted by Confess, Fletch at 9:54 AM on March 13, 2009

My wild guess is that they are different because it is harder to get a new aircraft buckle design approved than it is a car buckle (or rather, more expensive), and the improvements to car design were driven by market forces (people wanting more convenient, more comfortable belts) that are not as strong with aircraft (the owners, the airlines, don't care as much).

In other words, aircraft and car buckles were the same at one point, but the economic and regulatory forces affecting aircraft buckles have slowed aircraft buckle evolution relative to car buckles.

end wild guess mode
posted by zippy at 10:45 AM on March 13, 2009

My guess is that the relatively unsophisticated design of the commercial aircraft seatbelt is a tacit nod to the fact that, due to the overwhelming forces involved, the belt won't help you much in an aircraft crash other than one gentle enough to be survivable with or without a chest restraint. On an airliner, the seatbelt's function is primarily to keep you from flying around the cabin when the plane experiences turbulence severe enough to produce a negative-G situation, not to provide protection in the event of an accident.
posted by killdevil at 12:24 PM on March 13, 2009

I'm with killdevil, but also consider that the action of opening an airplane seatbelt (pulling the tab up and away) versus the car (pressing down on a button or latch) is much easier to fumble open correctly, especially if the person opening it is the flight attendant instead of the user.
posted by odinsdream at 12:57 PM on March 13, 2009

They're the same as my car.

Though they were probably remodeled in the same year too.
posted by Ookseer at 2:36 AM on March 14, 2009