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Airplane Crash Safety Today Vs Past  
User currently offlinewdleiser From United States of America, joined Apr 2004, 961 posts, RR: 4
Posted (3 years 8 months 4 weeks ago) and read 5134 times:

Since the topic about aircraft age and the need to retire them got deleted, I had asked a question that I am very curious to find the answer too.

How does the safety of a new airliner compare to that of an old one?

I am talking about DC-9 vs a 2010 737.

We all know if you properly maintain a 1967 Mustang it will run just fine with minimal problems.
We also know if you properly maintain a 2010 Honda Civic it will run just fine too with minimal problems and far better fuel efficiency.

In 1967 there was no such thing as a crumple zone on a car. If you backed into a poll there would be a ding on the bumper or the bumper would bend. If you back into a poll with a Honda Civic the bumper essentially shatters.

Now when you get into a head on collision at 55mph in the 67 Stang, the engine is in your lap, the steering wheel in the back seat, and you are probably dead and at the very least severely injured with numerous broken bones and internal damage. Seatbelt technology has changed drastically over the years but those are easy to update.

In the 2010 Honda Civic, when you get into a 55mph head on collision, the frame above the doors buckle with the impact and absorb alot of the energy as does the hood and engine compartment. Everything around the passenger compartment crumples and absorbs as much of the impact as possible while trying to keep the passenger area intact and the passengers safe. The Civic may look like Godzilla ate it but the engine won't be in the front seat and the air bags will have softened the blow and the likely hood of survival would be much higher than the 67 Mustang.

What I would like to know is this: What have aircraft producers(Boeing, Airbus, Bombardier etc...) done to increase the structural safety/integrity of the airframe in the event of a crash to try as much as it is feasible in a plane crash to reduce passenger injury and/or death. If they have made any improvements at all.



This is thread is not suppose to stir up any "Old Planes fall out of the Sky and no matter how much maintenance they receive, they are still dangerous and new planes don't crash". I am simply wanting to know if there has been any improvement in crash safety like the car industry has done.

13 replies: All unread, jump to last
 
User currently offlinem11stephen From United States of America, joined Aug 2008, 1247 posts, RR: 1
Reply 1, posted (3 years 8 months 3 weeks 6 days 23 hours ago) and read 5075 times:

Well old airplanes have to meet the same standards as new planes for the most part. For example older planes have been retrofitted with floor level escape lights. However, newer planes may have 16G seats and less flammable materials where as older planes may not have these.


My opinions, statements, etc. are my own and do not have any association with those of any employer.
User currently offlineHAL From United States of America, joined Jan 2002, 2558 posts, RR: 53
Reply 2, posted (3 years 8 months 3 weeks 6 days 23 hours ago) and read 5049 times:

Most of the crash safety improvements over the past few decades have to do more with the interiors & seats than the structure of the airframe.

The airframes in use today aren't much different than those of the 1960's in terms of safety design. They have to be light enough for fuel economy, and if your plane turns into a lawn dart, no amount of structural reinforcement will keep you from turning into strawberry jam. The structure is already strong enough to protect passengers against most moderate accidents such as runway overruns. And in reality what killed a majority of people in 'survivable' crashes over the years was smoke inhalation, and inability to exit the aircraft. The first part (smoke) has been worked on through the use of fire retardant materials inside the cabin. The other part was addressed by making the seats more crash-worthy. In years past a crash may have been survivable, but the seats either buckled (causing people to be trapped) or didn't budge at all, causing spinal injuries that prevented people from escaping the burning wreckage. Also, improved escape lighting allows people to find the exits better, even in a smoky cabin. Today passengers are more likely to survive the impact, and find their way out, which does increase the survival rate.

But by far the biggest reason for lower accident death rates these days is simply the lack of accidents. That comes from years of effort on the part of governments, manufacturers, and other interest groups (such as the Airline Pilots Association) being able to examine accidents in great detail to understand what went wrong, and how to prevent it from happening in the first place. CVR's and better forensic examination procedures brought about changes such as Windshear alerts, GPWS, TCAS, Crew fatigue rules, and more. This is by far the biggest reason we have safer flying today. Yes, the changes in the construction of the planes themselves has helped a little, but not as much as with automobiles.

(Note, I am a member of my airline's accident investigation team, and have been through extensive training in the subject)

HAL



One smooth landing is skill. Two in a row is luck. Three in a row and someone is lying.
User currently offlinespacecadet From United States of America, joined Sep 2001, 3611 posts, RR: 12
Reply 3, posted (3 years 8 months 3 weeks 6 days 21 hours ago) and read 4921 times:

In addition to the seats, the design of the floor and the floor supports has been improved as well. Many early jet crashes involved severe floor buckling and failure of seat supports that led to fatalities in what were otherwise survivable accidents.

Another thing that hasn't been mentioned is the overhead bins. Don't forget that in the early days of the passenger jet, there were no bins - just overhead racks, like on a train or a bus. In an accident (or even in turbulence), you'd have objects flying all over the cabin, turning into dangerous projectiles. The bins themselves are a safety feature.

There have been some specific improvements to the external aircraft structure, but mainly as a result of specific problems that either led to accidents or made them worse. There hasn't been a wholesale strengthening of the overall structure. For example, engine pylon design has improved over the years to make engine detachment less likely and safer if it does happen (and sometimes you actually want it to, but you want it to happen in a safe manner). T-tails are less common these days, but any new t-tail design takes into account the deep stall characteristics of these planes, which was a pretty inexact science when the early t-tail jets were developed. I guess you'd put this kind of thing under "accident avoidance" rather than "accident survivability", but the point is these are improvements to aircraft design and structure that make flying safer.



I'm tired of being a wanna-be league bowler. I wanna be a league bowler!
User currently offlineMarkHKG From United States of America, joined Dec 2005, 960 posts, RR: 2
Reply 4, posted (3 years 8 months 3 weeks 6 days 19 hours ago) and read 4828 times:

Another innovation are aircraft seat-belts that have an airbag in them, which are now being installed with increasing frequency, particularly on unusually configured business class seats.

http://amsafe.com/products/detail.php?id=4&type=categories

Quoting wdleiser (Thread starter):
What have aircraft producers(Boeing, Airbus, Bombardier etc...)

You might be interested in this fascinating article that discusses what Boeing engineers had to do to ensure the 787 met crash-worthiness requirements (in effect, ensuring that there was an aircraft-type crumple zone)

http://seattletimes.nwsource.com/htm...hnology/2012201098_787tests27.html

Quoting m11stephen (Reply 1):
However, newer planes may have 16G seats

I agree this is a key safety innovation. The law went into effect in Oct 2009 but aircraft manufacturers have been building new aircraft to this standard for several years now. Essentially, the FAA regulation stipulates that everyone should be able to survive a 16G impact regardless if they are the pilot, flight attendant or passenger. Building impact-absorbing seating, include designs which absorb head impacts, are key to meeting this requirement for the economy-class passenger.

You can read about this here:

http://seattletimes.nwsource.com/htm...oors/2002571372_webairseats19.html



Release your seat-belts and get out! Leave everything!
User currently onlineSEPilot From United States of America, joined Dec 2006, 6837 posts, RR: 46
Reply 5, posted (3 years 8 months 3 weeks 6 days 11 hours ago) and read 4590 times:

The biggest change has been in training and procedures, as well as better understanding of dangerous weather phenomenon (such as microbursts), technology to detect and procedures to avoid them. The safety record of the DC-9 today is just as good as the latest models designed recently, which shows that it is not the airframe that is responsible for the tremendous increase in safety. Crash survivability is a moot point if you avoid the crash in the first place, and the FAA and the airlines working together have done an absolutely outstanding job of doing just that. The biggest change, and probably the biggest contributor, to this has been CRM, which has revolutionized cockpit culture and removed the "captain as god" syndrome.


The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlinerfields5421 From United States of America, joined Jul 2007, 7607 posts, RR: 32
Reply 6, posted (3 years 8 months 3 weeks 6 days 9 hours ago) and read 4477 times:

Quoting spacecadet (Reply 3):
Another thing that hasn't been mentioned is the overhead bins. Don't forget that in the early days of the passenger jet, there were no bins - just overhead racks, like on a train or a bus. In an accident (or even in turbulence), you'd have objects flying all over the cabin, turning into dangerous projectiles. The bins themselves are a safety feature.

I would disagree from my experience.

I flew on many of the aircraft with open overhead racks. You were simply not allowed to put anything heavier than a book up there. It was hats and coats only. Your carryon went under the seat in front of you or was taken and placed in the baggage compartment.

Today with overhead bins, I see something fall out of a bin on average 1 out of 3 flights I take. Either while in flight or upon landing - relatively normal landings. The bins today do not have latches strong enough to hold them closed in a rough impact scenario.

Every survivable accident we hear about today, several bins come open and objects strike people in seats, impede the safe, quick exit from the aircraft.


User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9511 posts, RR: 52
Reply 7, posted (3 years 8 months 3 weeks 6 days 3 hours ago) and read 4270 times:

Quoting wdleiser (Thread starter):
I am simply wanting to know if there has been any improvement in crash safety like the car industry has done.

Structure is not getting stronger. In some cases, it is getting weaker since the stress calculations are becoming more accurate and material properties are more predictable. Everything has a design load and it is designed to that with little extra margin. There is tremendous pressure to keep weight down on a plane,so overdesigning parts for ultimate strength is not adventagious.

Airplanes are designed not to have failures that would result in a loss of control. Safety has improved in the cabin as previously said. Insulation has to survive 4 minutes exposed to jetfuel fire. Seats now are designed to as many as 16Gs. All fabrics are flammability tested. Smoke tests have improved.

As far as other safety improvements go, the whole certification process is bigger than it ever was before. Everything is certified and tested.

Quoting rfields5421 (Reply 6):
Today with overhead bins, I see something fall out of a bin on average 1 out of 3 flights I take. Either while in flight or upon landing - relatively normal landings. The bins today do not have latches strong enough to hold them closed in a rough impact scenario.

On new airplanes they are tested to remain secure at 16G with maximum design load. However, a broken or damaged latch may not be strong enough.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 8, posted (3 years 8 months 3 weeks 6 days 1 hour ago) and read 4178 times:

Quoting rfields5421 (Reply 6):
The bins today do not have latches strong enough to hold them closed in a rough impact scenario.

Older ones are grandfathered in (like virtually everything else in certification). New stuff couldn't be certified unless it stays closed under the design loads (which include impact). As RoseFlyer said, if the latch is damaged or broken or (really common) no properly closed in the first place, all bets are off.

Quoting rfields5421 (Reply 6):
Every survivable accident we hear about today, several bins come open and objects strike people in seats, impede the safe, quick exit from the aircraft.

Which is why the evacuation test requires that blocking luggage and personal effects be placed around the cabin...the whole interior is designed so that you can survive the crash and escape before the fire burns through, including all the real world factors like darkness, blocked exists, old/young/large/small people, luggage & bins blocking paths, etc.

Tom.


User currently offlineVV701 From United Kingdom, joined Aug 2005, 7403 posts, RR: 17
Reply 9, posted (3 years 8 months 3 weeks 6 days ago) and read 4157 times:

The Aircraft Crashes Records Office in Geneva has analsed 19,632 accidents to aircraft configured to carry 6 or more people.

Of these accidents technical reasons (where the age of the aircraft could possibly be a factor) were determined as the prime cause in just 20.7 per cent. For 67.6 per cent of all accidents human error was determined to be the prime cause while other major factors were the weather (6.0 per cent), sabotage (3.3 per cent) while 2.5 per cent were attributed primarily to 'other' causes.

More at:

http://www.baaa-acro.com/Statistiques%20diverses.htm

Interestingly the number of years reported by the ACRO where deaths exceeded 1,000 in each decade is:

1940s: 2
1950s: 0
1960s: 5
1970s: 9
1980s: 5
1990s: 3
2000s: 0

With the growth in commercial air travel over the last 20 years the recent record is commendable.


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 10, posted (3 years 8 months 3 weeks 5 days 8 hours ago) and read 3938 times:

Quoting VV701 (Reply 9):

With the growth in commercial air travel over the last 20 years the recent record is commendable.

I've heard it said that the industry has to improve safety at something like 10% per year just to hold the accident rate per year constant. If we just held the rate per flight hour constant, you'd end up having a major accident about once a week within a few years.

Tom.


User currently offlinespacecadet From United States of America, joined Sep 2001, 3611 posts, RR: 12
Reply 11, posted (3 years 8 months 3 weeks 5 days 6 hours ago) and read 3841 times:

Quoting rfields5421 (Reply 6):

I flew on many of the aircraft with open overhead racks. You were simply not allowed to put anything heavier than a book up there.

In an accident, a book is a dangerous projectile.

Anyway, I think this photo speaks for itself:


View Large View Medium
Click here for bigger photo!

Photo © Stefan Ottosson



Everything up there is a dangerous projectile during an accident. All that crap is coming down in an accident. Yes, it's hard to tell what everything up there is, but that is a rack literally overflowing with junk. And every one of those objects has kinetic energy that's going to be uncontained in an accident. Even coats have kinetic energy. A coat with a strap and buckle on it flying around the cabin could knock a person unconscious if it hit them the wrong way.

[Edited 2010-11-09 12:21:59]


I'm tired of being a wanna-be league bowler. I wanna be a league bowler!
User currently offlineNZ001 From UK - England, joined Nov 2010, 59 posts, RR: 0
Reply 12, posted (3 years 8 months 3 weeks 5 days 6 hours ago) and read 3822 times:

Don't forget that with every plane crash, the producers learn something new.
You can learn a lot from watching Air Crash Investigation  

Think of last April when the skies over Europe were forced to close for a month costing the industry billions...
That was due to the famous events of speedbird 9 - otherwise who knows what could have happened last April.

So I like to think that the aircraft producers have learnt a lot over the years from where they have gone wrong.


User currently offlinekaitak From Ireland, joined Aug 1999, 12411 posts, RR: 37
Reply 13, posted (3 years 8 months 3 weeks 5 days 5 hours ago) and read 3797 times:

I think that a major factor here is human factors; I'm not just talking about fatigue, but rather about psychology and the application of this to flying; fifty years ago, at the dawn of the jet age (and one could argue, up to recently - still, in many places), there was very little understanding of CRM; the approach was "I am the captain, this the cockpit, you (the FO) are the resource"; there was a military approach to flying, which left very little room for second guessing the absolute authority of the captain; a lot of that has changed now. Airlines like CX, for example, have introduced a safety process based on the Reason (or Swiss cheese) model, identifying latent dangers and how these can be addressed.

All of this is not to downgrade the importance of other issues, such as windshear awareness; let's not forget technology either - EGPWS, TCAS, etc.

I think that one of the major fears I have is that even though some airlines can spend billions upon billions on new aircraft, simulators, the best facilities etc, none of that is a substitute for a poor approach towards issues like confidential reporting; the airline's culture is as important as the hardware; if you have a pilot who is in the least bit concerned that his concern is going to result in an "invitation" to the chief pilot's office for a chat and biscuits (and a dressing down), then he won't submit a report and errors will go unreported.


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