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Why Seat Belt On Planes Not The Inertia Type?  
User currently offlineBA747 From Venezuela, joined Sep 2005, 107 posts, RR: 1
Posted (6 years 1 month 1 week 2 days 18 hours ago) and read 13341 times:

Hi, I was wondering instead of the seat belt that one have to adjust, why airlines don´t put the car type?


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35 replies: All unread, showing first 25:
 
User currently onlineB747forever From Sweden, joined May 2007, 17155 posts, RR: 10
Reply 1, posted (6 years 1 month 1 week 2 days 18 hours ago) and read 13322 times:



Quoting BA747 (Thread starter):
, I was wondering instead of the seat belt that one have to adjust, why airlines don´t put the car type?

I wonder that too. The car belt type seems much safer.



Work Hard, Fly Right
User currently offlineCaryjack From United States of America, joined May 2007, 338 posts, RR: 0
Reply 2, posted (6 years 1 month 1 week 2 days 18 hours ago) and read 13313 times:

I'd guess higher weight, cost and maintenance with lower reliability.  Smile
Cary


User currently offlineBoeing767mech From United States of America, joined Dec 2000, 1031 posts, RR: 3
Reply 3, posted (6 years 1 month 1 week 2 days 18 hours ago) and read 13303 times:

Quoting BA747 (Thread starter):
Hi, I was wondering instead of the seat belt that one have to adjust, why airlines don´t put the car type?

Two words:

weight and cost. the reels for the seat belts weight about 2 pounds more than a normal seat belt. Also is take 5 mintues to change a seat belt now, with a reel it would take longer and would casue delays on turn arounds.

David

[Edited 2008-11-19 15:36:10]


Never under-estimate the predictably of stupidty
User currently offlineOvercast From United Kingdom, joined May 2005, 161 posts, RR: 0
Reply 4, posted (6 years 1 month 1 week 2 days 18 hours ago) and read 13293 times:

I think Inertia Seat Belts are good at locking in a certain plane, i.e. They will lock when you hit a wall. But not that good if the car gets drops 20 feet vertically.

So in aviation terms they may be ok when you crash land and hit something, but probably won't stop you hitting the ceiling in turbulance.


User currently onlineB747forever From Sweden, joined May 2007, 17155 posts, RR: 10
Reply 5, posted (6 years 1 month 1 week 2 days 18 hours ago) and read 13292 times:



Quoting Boeing767mech (Reply 3):
weight and cost.

Well is weight and cost more important that safety??



Work Hard, Fly Right
User currently offlineWN700Driver From , joined Dec 1969, posts, RR:
Reply 6, posted (6 years 1 month 1 week 2 days 18 hours ago) and read 13293 times:

Not 100% sure, but I'll make like OJ and take a stab at it. It probably has something to do with the fact that seat belts are more to keep you from banging your head into the overhead or PSU's (during severe turbulence or rough landings) than keep you alive through a wreck. Even on our deminuative Dash 8-300s, in a collision at speeds of over 180 per, belts wont do much for you, inertia or otherwise.

Edit: The shoulder straps up front (Pilots, observer's and FA's) are inertia types. But only the shoulder parts. The lap sections are still the manually tightening type. Can't believe I forgot that.   

[Edited 2008-11-19 15:36:41]

[Edited 2008-11-19 15:37:44]

User currently offlineDL767captain From United States of America, joined Mar 2007, 2539 posts, RR: 0
Reply 7, posted (6 years 1 month 1 week 2 days 17 hours ago) and read 13185 times:

It seems to me the seat belts are there for if the aircraft plunges (like the Qantas A330) to keep people in their seats, I can't really imagine any type of seatbelt keeping passengers alive in an actual crash

User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 8, posted (6 years 1 month 1 week 2 days 17 hours ago) and read 13129 times:



Quoting BA747 (Thread starter):
Hi, I was wondering instead of the seat belt that one have to adjust, why airlines don´t put the car type?

I'd agree with weight and reliability.

Quoting B747forever (Reply 5):

Well is weight and cost more important that safety??

Not more important, but when safety is equal, you don't go for more weight and less reliability. An inertia reel isn't really safer than a regular airplane belt, if you're wearing the airplane belt properly.

Also, there is *always* a tradeoff between cost (weight, reliability, etc.) and safety. This rubs a lot of people the wrong way, but it's true. You could make airplanes much safer than they are, but it would drive the cost of flying so high that nobody could afford it, so there's no point. It's the same reason that the FAA doesn't mandate that all AD's be done right away, even though they have that power.

Tom.


User currently offlineCrjfixer From United States of America, joined Mar 2008, 172 posts, RR: 0
Reply 9, posted (6 years 1 month 1 week 2 days 16 hours ago) and read 13099 times:

The Crew seatbelts on most aircraft are the inertia type, but not for the pax. And as DL767 said the seatbelts are mainly for turbulence and the like. In an actual crash a seatbelt wont help much no matter what type sadly.

User currently offlineUAL Bagsmasher From United States of America, joined Sep 1999, 2148 posts, RR: 10
Reply 10, posted (6 years 1 month 1 week 2 days 16 hours ago) and read 13031 times:

To change a pax seat belt takes about 30 seconds. To change the inertia reel on a pilot seat (on a CRJ-200) can take over a half hour depending on how any times you've done one.

User currently offlineVV701 From United Kingdom, joined Aug 2005, 7743 posts, RR: 17
Reply 11, posted (6 years 1 month 1 week 2 days 16 hours ago) and read 13025 times:

The functions of a car seat belt and an airlimne passenger seat belt are entirely different.

A car seat belt is designed to minimise injury when the car is in a full head-on crash. If you have a full head-on crash in an aircraft . . .

An aircraft seat belt is designed to minimise injury during severe turbulance (be it turbulance caused by a natural atmospheric phenomena, by aircraft performance or relatively low stability during take-off and landing).

Hence the requirement is to wear a car seat belt whenever the car is in motion. But airliners are fitted with "fasten seat belt" signs as it is not required to wear them at all times that the aircraft is in motion.

Clearly if fitting lap belts instead of inertia chest belts is a cost saving exercise designed to save installation costs and weight then the airlines are missing a lot of opportunities. Why go to the bother and cost of fitting the seat-belt signs when they could save that cost and weight simply with a safety instruction card that told the passengers to keep belted up at all times?

Other possible cost savings they could consider would the cost and weight saving of getting rid of WCs and galleys. If passengers had to remain belted-up at all times when the aircraft was in motion they clearly could not use the WCs and serving food and drink during a flight would cause passengers significant problems. So would we need FAs? Or is their safety unimportant? After all if they and the passengers had to remain belted-up throughout the flight what would they do?

Yes. It is all prertty ridiculous. But think about it. Is it any less ridiculous than suggesting airlines are putting cost savings before passenger safety by using lap belts and not inertia reel chest belts?

And a final thought. You are in an airliner and wearing an inertia reel, car-type, crash (not safety) belt. The aircraft is in trouble and is going to crash land. So what do you have to do? First you release the seat belt catch. Only then can you adopt the position recommended by all airlines' safety cards in the event of a crash. So your inertia reel belt would actually be a safety hazzard as on impact you will now be thrown about the cabin.


User currently offlineDfwRevolution From United States of America, joined Jan 2010, 1001 posts, RR: 51
Reply 12, posted (6 years 1 month 1 week 2 days 16 hours ago) and read 13001 times:



Quoting B747forever (Reply 5):
Well is weight and cost more important that safety??

Yes, there is a cost/benefit ratio to everything. Contrary to what we tell our children, life is not "priceless."


User currently offlineNWADC9 From United States of America, joined May 2004, 4898 posts, RR: 9
Reply 13, posted (6 years 1 month 1 week 2 days 16 hours ago) and read 12978 times:



Quoting WN700Driver (Reply 6):
Edit: The shoulder straps up front (Pilots, observer's and FA's) are inertia types. But only the shoulder parts. The lap sections are still the manually tightening type.

What about the front seats on RJs like the Do328 where they have a shoulder strap along with the lap belt? Are they inertia types too?



Flying an aeroplane with only a single propeller to keep you in the air. Can you imagine that? -Capt. Picard
User currently offlineSPREE34 From United States of America, joined Jun 2004, 2266 posts, RR: 9
Reply 14, posted (6 years 1 month 1 week 2 days 15 hours ago) and read 12954 times:



Quoting B747forever (Reply 5):
Well is weight and cost more important that safety??

Who says they are safer?



I don't understand everything I don't know about this.
User currently offlineTZTriStar500 From United States of America, joined Jan 2004, 1460 posts, RR: 9
Reply 15, posted (6 years 1 month 1 week 2 days 15 hours ago) and read 12908 times:



Quoting WN700Driver (Reply 6):
It probably has something to do with the fact that seat belts are more to keep you from banging your head into the overhead or PSU's (during severe turbulence or rough landings) than keep you alive through a wreck. Even on our deminuative Dash 8-300s, in a collision at speeds of over 180 per, belts wont do much for you, inertia or otherwise.



Quoting DL767captain (Reply 7):
It seems to me the seat belts are there for if the aircraft plunges (like the Qantas A330) to keep people in their seats, I can't really imagine any type of seatbelt keeping passengers alive in an actual crash



Quoting VV701 (Reply 11):
An aircraft seat belt is designed to minimise injury during severe turbulance (be it turbulance caused by a natural atmospheric phenomena, by aircraft performance or relatively low stability during take-off and landing).

While this may seem logical, this is not true. Airline seat belts are designed to regulations to restrain a 50th percentile male in the seat to the same crash and/or dynamic conditions as the seat itself (e.g. a 9g seat requires a 9g seat belt and a 16g seat requires a 16g seat belt). They are dynamically tested with and considered an integral part of the seat and must also meet TSO C22. Seat belts are really designed for crash conditions along with the seats and anything else in the passenger cabin as this is the most critical.

I can recall that mandatory seat belt use used to be only during takeoff and landing, but about a decade or so ago with the increase in turbulence related injuries, airlines have been requiring them more during flight. FAR 121 only requires a seat and seat belt be available for each occupant, but is only required to be secured during movement on the surface, takeoff, and landing.



35 years of American Trans Air/ATA Airlines, 1973-2008. A great little airline that will not be soon forgotten.
User currently offlineMir From United States of America, joined Jan 2004, 21882 posts, RR: 55
Reply 16, posted (6 years 1 month 1 week 2 days 14 hours ago) and read 12801 times:



Quoting B747forever (Reply 5):
Well is weight and cost more important that safety??

There is always a tradeoff. In this case, an inertia seatbelt is not going to be much safer than the standard seatbelt, if at all. Therefore, weight and cost are big considerations.

-Mir



7 billion, one nation, imagination...it's a beautiful day
User currently offlineCaryjack From United States of America, joined May 2007, 338 posts, RR: 0
Reply 17, posted (6 years 1 month 1 week 2 days 12 hours ago) and read 12669 times:



Quoting SPREE34 (Reply 14):
Who says they are safer?

I don't. In fact I don't see how they could be. Inertia types are designed to reel and unreel seat belt fabric for comfort while locking for safety as required. If they fail to reel it in or lock, the belt won't hold and if they fail to reel it out the belt will become too tight. There are just too many moving parts to be as reliable, therefore safe, as the belt now being used.
Cary


User currently offlineWNCrew From United States of America, joined Jun 2006, 1485 posts, RR: 10
Reply 18, posted (6 years 1 month 1 week 2 days 11 hours ago) and read 12660 times:

Also, aircraft seats aren't designed to stay stationary (like that in a car) but they are designed to collapse and to be impacted by the human body. Were you to install an inertia reel seatbelt or shoulder harness-strap on an aircraft seat, the seatbelt would pull the seat with it instead of letting it do it's job of absorbing the impact of the occupant behind you. This is something I learned from my FAA training.

When pax say "Why do you get the harness and we just get the seatbelt?" I just say 'We can hardly get you to wear the seatbelt, muchless a harness..." They usually realize my point and smile. I find it funny that pax get up when they see FA's get up regardless of turbulence OR the seatbelt sign, yet FA's stay buckled until taxi-in and Seatbelt sign is extinguished and pax unbuckle as SOON as we land...huh



ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
User currently offlineLarSPL From Netherlands, joined Apr 2002, 473 posts, RR: 0
Reply 19, posted (6 years 1 month 1 week 2 days 7 hours ago) and read 12475 times:

i don't know why the safety card is played here.
even on a car seat belt the part around the middle is not inertia.
only the shoulder is an inertia system.
that inertia system is there because if you would have a belt around your shoulder which would not give in during a crash it would lead to more damage than an inertia belt (because of the inertia lock the amount of crash force is absorbed by the inertia reel.).
however: you dont want your waist to move during a crash nore is the inertia system necessary at the waist.
the crash position in aircraft for pax is designed to do the same as a inertia reel; absorbe the crash force.



facebook.com/ddaclassicairlines
User currently offlineBill142 From Australia, joined Aug 2004, 8467 posts, RR: 8
Reply 20, posted (6 years 1 month 1 week 2 days 7 hours ago) and read 12470 times:



Quoting VV701 (Reply 11):
If you have a full head-on crash in an aircraft . . .

Aircraft aren't exactly designed for head on crashes...


User currently offlineDocLightning From United States of America, joined Nov 2005, 20368 posts, RR: 59
Reply 21, posted (6 years 1 month 1 week 2 days 5 hours ago) and read 12115 times:



Quoting Overcast (Reply 4):
I think Inertia Seat Belts are good at locking in a certain plane, i.e. They will lock when you hit a wall. But not that good if the car gets drops 20 feet vertically.

Depends on the type. There is one kind of reel that locks if it starts to spin too quickly. So that would not depend on direction of force, just the force.

But that reel is heavier. And if you need the seatbelt to be a bit looser, just loosen it.

For those of you talking about crashes, a seatbelt is worthless when a machine made of thin aluminum hits the ground or water at a few hundred MPH. That's not what it's for.

It's to keep you from getting thrown around the cabin in a sudden extreme maneuver or during turbulence. That's why you should keep it on at all times. I've definitely been on some flights where the seatbelt was the only thing holding me in my seat.

Now, someone needs to throw a few million dollars at a grant to figure out why turbulence ONLY seems to happen 30 seconds AFTER you have been served hot coffee.  Wink


User currently offlineVoar From Canada, joined Jul 2008, 95 posts, RR: 0
Reply 22, posted (6 years 1 month 1 week 2 days 3 hours ago) and read 11664 times:

Seat belts on newer piston aircraft are generally of the inertial type for all occupants, so not sure about the weight argument. Some manufacturers even have airbags on the seat belts for increased protection.

I would think that on an airliner an inertial type seat belt would not be comfortable for passengers as it always is pressing against you, would make it harder to sleep for example. On a light aircraft that is not possible, passengers have to sit upright all the time.


User currently offlineGuth From Canada, joined Nov 2005, 15 posts, RR: 0
Reply 23, posted (6 years 1 month 1 week 2 days 1 hour ago) and read 10879 times:

I used to fly a Cessna 172R that had inertia reel belts. They were most annoying. As the belts aged they started to fray and would get caught up in the retraction mechanism. Just before I stopped flying the plane I would have to stick my fingers into the reel every time and manually rotate it to get the belt to retract or unlock or do anything.

I say keep the old style belts as the inertia reel type aren't worth the hassle.


User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 24, posted (6 years 1 month 1 week 2 days 1 hour ago) and read 10689 times:



Quoting B747forever (Reply 1):

I wonder that too. The car belt type seems much safer



Quoting BA747 (Thread starter):
why airlines don´t put the car type?

Very simple.... because with a car you have 3 point hard contact points with the floor/frame, the B Pillar and the Clip/Latch... with an aircraft passenger seat you have no way to add the third point.



"It's not the size of the dog in the fight, but the size of the fight in the dog"
25 VScaptain : VS have inertia type belts on there Upper Class Suites.
26 Boeingluvr : An Inertia harness/belt can cost in excess of 700-1000 dollars each! that's huge money when you think of an entire fleet, not to mention spares etc...
27 Ckfred : Here's something that's slightly off the topic. Why don't airplanes use car belt buckles? In a car, you push a button to release the seat belt. On an
28 Birdbrainz : This is off-topic, but I remember reading somewhere that most passengers are killed by fire, smoke, and fumes, and not the actual impact. This is esp
29 JOEYCAPPS : IMHO I believe that jumpseats in most aircraft are rear facing. The inertia seatbelts are a plus because as the aircraft takes off, pax are thrown in
30 OldAeroGuy : Plus the certification hassle. Please explain how the current airplane safety belts are unsafe.
31 Post contains images UniTED : I actually know of the Inertia type existing in passenger seats. In the new United First Suites, there are the shoulder straps. Interestingly enough,
32 TZTriStar500 : Because its likely the push button latch would not survive the 16g airline seat belt requirements. They are not as they meet current regulations. Bec
33 Bongodog1964 : The requirements for a car seat belt, and a plane seat belt are entirely different. A car belt has the requirements to allow movement of the upper bod
34 123 : In the SQ new C Class, you have two seatbelts: When the seat is in normal position, it´s a special seatbelt with an airbag (yup!) - normal locking/si
35 PGNCS : Correct me here if I am wrong, but for most airliners the LAP BELTS in the cockpit are NOT inertial. I have flown 8 types of airliners under FAR 121
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