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Why So Few Exits?  
User currently offlineNitepilot79 From Turkey, joined May 2008, 308 posts, RR: 0
Posted (5 years 5 months 2 weeks 1 day 10 hours ago) and read 4729 times:

I just saw a picture of an Air Canada 762; and happened to notice that it had 6 total exits . 2 over-wing and 4 full-size exits. My question is: why on earth does the 734 have 2 more exits with less passenger capacity? Perhaps safety standards changed as the 734 is a bit younger than the 762, even still, the 732 has the same # of exits as the 762. Seems to me the increase of pax capacity(762) should have warranted more exits than a on 732. PS- Not trying to cry over spilled milk, just curious.  eyebrow 


En Buyuk Turkiye, Baska Buyuk Yok!
24 replies: All unread, jump to last
 
User currently offlineLY777 From France, joined Nov 2005, 2744 posts, RR: 2
Reply 1, posted (5 years 5 months 2 weeks 1 day 9 hours ago) and read 4684 times:



Quoting Nitepilot79 (Thread starter):
I just saw a picture of an Air Canada 762; and happened to notice that it had 6 total exits . 2 over-wing and 4 full-size exits. My question is: why on earth does the 734 have 2 more exits with less passenger capacity? Perhaps safety standards changed as the 734 is a bit younger than the 762, even still, the 732 has the same # of exits as the 762. Seems to me the increase of pax capacity(762) should have warranted more exits than a on 732. PS- Not trying to cry over spilled milk, just curious

I aked myself the very same question, and in fact, there are 2 main reasons:

- the 762 has 2 aisles, so evacuation would be easier
- the doors of the 767 are much wider than the 737

Hope this helps!



אמא, אני מתגעגע לך
User currently offlineUal747 From , joined Dec 1969, posts, RR:
Reply 2, posted (5 years 5 months 2 weeks 1 day 9 hours ago) and read 4662 times:

Wider doors, twin aisle aircraft. Basically, it's two RJ's wide. One a CRJ and one an ERJ on either side of the aisle, with bigger doors.

All of these evacuations have been timed and are in full compliance with safety standards. You won't find manufacturers putting on any more doors than they need because of the weight.

The 763 with only 2 doors and 2 over wing exits is a bit of a stretch to me personally, but I guess it works the same way.

UAL


User currently offlineHAWK21M From India, joined Jan 2001, 31712 posts, RR: 56
Reply 3, posted (5 years 5 months 2 weeks 1 day 9 hours ago) and read 4607 times:

Evactuation Tests are carried out to determine the speed of the Evacuation of the main pax cabin.If not within the permissible timeframe,the regulatory authority would insist addition of exits to fulfill that requirement prior to certification.
regds
MEL.



Think of the brighter side!
User currently offlineBMI727 From United States of America, joined Feb 2009, 15836 posts, RR: 27
Reply 4, posted (5 years 5 months 2 weeks 22 hours ago) and read 4467 times:



Quoting LY777 (Reply 1):
- the 762 has 2 aisles, so evacuation would be easier

Aren't the certification tests done using the exits on only one side of the aircraft?



Why do Aerospace Engineering students have to turn things in on time?
User currently offlineKELPkid From United States of America, joined Nov 2005, 6428 posts, RR: 3
Reply 5, posted (5 years 5 months 2 weeks 22 hours ago) and read 4458 times:



Quoting BMI727 (Reply 4):

Aren't the certification tests done using the exits on only one side of the aircraft?

Technically, with only 50% of the exits operable....Airbus chose to disable all of the slide packs on one side for the A380 evacuation test  Wink They could have just as easily randomly chosen which exits would have worked and which ones didn't and been in full compliance of the letter of the law. The test subjects, however, can't know what's going on, IIRC...



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offline2H4 From United States of America, joined Oct 2004, 8956 posts, RR: 60
Reply 6, posted (5 years 5 months 2 weeks 21 hours ago) and read 4446 times:
AIRLINERS.NET CREW
DATABASE EDITOR



Quoting KELPkid (Reply 5):
The test subjects, however, can't know what's going on, IIRC...

Didn't Airbus gather a bunch of college students and offer some kind of monetary bonus if they all get out in time for the A380 tests? A stroke of brilliance, if you ask me. They could improve the times even further if a few hundred kegs of beer and swimsuit models were awaiting the college kids.

2H4



Intentionally Left Blank
User currently offlineHAWK21M From India, joined Jan 2001, 31712 posts, RR: 56
Reply 7, posted (5 years 5 months 2 weeks 18 hours ago) and read 4375 times:



Quoting BMI727 (Reply 4):
Aren't the certification tests done using the exits on only one side of the aircraft?

50% are supposed to be randomly deactivated.
regds
MEL.



Think of the brighter side!
User currently offlineBMI727 From United States of America, joined Feb 2009, 15836 posts, RR: 27
Reply 8, posted (5 years 5 months 2 weeks 17 hours ago) and read 4353 times:



Quoting KELPkid (Reply 5):
....Airbus chose to disable all of the slide packs on one side for the A380 evacuation test

This seems like it might be the most realistic scenario for having fewer exits available, like having a fire on one side or something.

Quoting 2H4 (Reply 6):
They could improve the times even further if a few hundred kegs of beer and swimsuit models were awaiting the college kids.

They could better simulate typically stupid pax by making them take the beer and models out of the overheads and carry them out with them.  Smile



Why do Aerospace Engineering students have to turn things in on time?
User currently offlineViscount724 From Switzerland, joined Oct 2006, 26021 posts, RR: 22
Reply 9, posted (5 years 5 months 2 weeks 16 hours ago) and read 4342 times:



Quoting Nitepilot79 (Thread starter):
I just saw a picture of an Air Canada 762; and happened to notice that it had 6 total exits . 2 over-wing and 4 full-size exits.

Some 762s operated by charter carriers with very high-density seating configurations were built with 4 over-wing exits to meet evacuation requirements, for example those ordered by Britannia Airways which had very tight 8-abreast seating with about 29 inch seat pitch and probably at least 100 more seats than the typical 7-abreast mixed-class 762 operated by most scheduled airlines. Not sure if any other carriers ordered 762s with the 4 overwing exits. Photos of two Britannia 762s with the additional over-wing exits below. (Britannia is now Thomson Airways and they no longer operate 762s.)


View Large View Medium
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Photo © Koksy
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Photo © Jordi Grife - Iberian Spotters



User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 10, posted (5 years 5 months 2 weeks 15 hours ago) and read 4326 times:



Quoting 2H4 (Reply 6):
Didn't Airbus gather a bunch of college students and offer some kind of monetary bonus if they all get out in time for the A380 tests?

That probably wouldn't have passed certification...the passengers used in the evacuation test are supposed to be a representative sample (age, size, fitness, gender, etc.). Just because 850+ money-starved college students can get out of an A380 in time doesn't mean a real passenger load could.

Tom.


User currently offlineMarkHKG From United States of America, joined Dec 2005, 960 posts, RR: 2
Reply 11, posted (5 years 5 months 2 weeks 14 hours ago) and read 4313 times:



Quoting KELPkid (Reply 5):
Airbus chose to disable all of the slide packs on one side for the A380 evacuation test

Actually, Airbus doesn't get to choose I believe - the monitoring regulatory agencies specify which exits are to be "deactivated". However I find that for whatever reason most of the evacuation certifications are done with "right" or "left" side only. In fact there are some mumblings that if you attempted to block off all the floor level exits on the A320 or B737-800 and made people go through all the overwings, they couldn't make the 90 second time limit even though all 4 overwings would still count as 50% of exits if the four Type I doors are blocked. I don't think an evacuation certification has ever attempted this.

Quoting 2H4 (Reply 6):
Didn't Airbus gather a bunch of college students and offer some kind of monetary bonus if they all get out in time for the A380 tests

No, competitive evacuations are not used during evacuation certification. Cranfield University conducted their own research after the Manchester Air Disaster using monetary compensation but it is unrelated to certification.



Release your seat-belts and get out! Leave everything!
User currently offlineMarkHKG From United States of America, joined Dec 2005, 960 posts, RR: 2
Reply 12, posted (5 years 5 months 2 weeks 14 hours ago) and read 4312 times:



Quoting Nitepilot79 (Thread starter):
4 full-size exits

To give you an idea of how dual lane versus single lane doors result in:

The Boeing 737 has a type I door. The FAA allows for 45 passengers per one pair of Type I doors.

The Boeing 767 has a type A door. The FAA allows for 110 passenger per one pair of Type A doors.

This is described in FAR 25.807



Release your seat-belts and get out! Leave everything!
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17185 posts, RR: 66
Reply 13, posted (5 years 5 months 2 weeks 14 hours ago) and read 4307 times:



Quoting MarkHKG (Reply 11):
Cranfield University conducted their own research after the Manchester Air Disaster using monetary compensation but it is unrelated to certification

They used monetary compensation to make people more motivated. It was thought that this more accurately modeled real conditions, since of course if the plane is in a real emergency people are more motivated to get out than in a simulated one.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offline2H4 From United States of America, joined Oct 2004, 8956 posts, RR: 60
Reply 14, posted (5 years 5 months 2 weeks 14 hours ago) and read 4305 times:
AIRLINERS.NET CREW
DATABASE EDITOR



Quoting Starlionblue (Reply 13):
They used monetary compensation to make people more motivated. It was thought that this more accurately modeled real conditions, since of course if the plane is in a real emergency people are more motivated to get out than in a simulated one.

That's what I thought. It makes sense...the cost of motivational compensation pales in comparison to the cost of treating all the burns and settling all the lawsuits when utilizing fully realistic motivational techniques.  Wink

2H4



Intentionally Left Blank
User currently offlineMarkHKG From United States of America, joined Dec 2005, 960 posts, RR: 2
Reply 15, posted (5 years 5 months 2 weeks 11 hours ago) and read 4265 times:

Quoting 2H4 (Reply 14):
treating all the burns and settling all the lawsuits when utilizing fully realistic motivational techniques.

To be clear, Airbus did not use monetary bonus incentives for the A380 evacuation. The only compensation was 60 Euros and a free lunch.

Cranfield University on the other hand, has used a system of monetary bonuses to increase competitive behavior in some of their studies. One study design for a 737 mockup involved the first 50% passengers off the study aircraft getting 5 British pounds. (Some studies later involved the first 75% passenger off). The results were somewhat horrendous: the addition of the monetary money resulted in bottlenecks at the bulkhead partitions and people getting stuck in the Type III overwing exits, while non-competitive (i.e. no bonus money) evacuation trials did not demonstrate this behavior.

And all for just 5 pounds!

[Edited 2009-07-14 23:36:58]


Release your seat-belts and get out! Leave everything!
User currently offlineFlyingColours From United Kingdom, joined exactly 11 years ago today! , 2315 posts, RR: 10
Reply 16, posted (5 years 5 months 2 weeks 7 hours ago) and read 4220 times:



Quoting MarkHKG (Reply 15):
Quoting 2H4 (Reply 14):
treating all the burns and settling all the lawsuits when utilizing fully realistic motivational techniques.

To be clear, Airbus did not use monetary bonus incentives for the A380 evacuation. The only compensation was 60 Euros and a free lunch.

Cranfield University on the other hand, has used a system of monetary bonuses to increase competitive behavior in some of their studies. One study design for a 737 mockup involved the first 50% passengers off the study aircraft getting 5 British pounds. (Some studies later involved the first 75% passenger off). The results were somewhat horrendous: the addition of the monetary money resulted in bottlenecks at the bulkhead partitions and people getting stuck in the Type III overwing exits, while non-competitive (i.e. no bonus money) evacuation trials did not demonstrate this behavior.

And all for just 5 pounds!

I believe that was after the Manchester Air Disaster of 1985, they wanted to conduct a study into evacuations since so many people lost their lives in that accident due to not being able to get out before being overcome by smoke & fumes before the cabin flashed over 90 or so seconds later.

Quoting Viscount724 (Reply 9):
Some 762s operated by charter carriers with very high-density seating configurations were built with 4 over-wing exits to meet evacuation requirements, for example those ordered by Britannia Airways which had very tight 8-abreast seating with about 29 inch seat pitch and probably at least 100 more seats than the typical 7-abreast mixed-class 762 operated by most scheduled airlines.

At one point we operated 3 ex BY 767-200s, G-SATR, G-BNYS & G-BOPB, all were fitted with 290 seats and 4 main exits and 4 overwings. I wouldn't say the seating was too cramped, sure on a long haul flight (BGI-LGW - I did it once, because a 763 went tech) it would be unbearable but it's not as bad as some would think, though if you are 6 feet tall then it's a different story....

A bit of history here, TR became a freighter years ago (incidentally it clipped a Bmi Baby 737 tail at Manchester), YS went to Air Seychelles and was supposed to be coming back to us in the winter, but due to our bankruptcy did not and has now been scrapped. "Papa Bravo" as the company preferred it to be called (we preferred "Pile 'O B&llocks" spent many months stored after XL's Bankruptcy but is now operating for Yemen Air (in our full colours), I believe alongside the ex Silverjet birds in their old liveries (incidentally all ex BY machines).

Quoting MarkHKG (Reply 11):
block off all the floor level exits on the A320 or B737-800 and made people go through all the overwings, they couldn't make the 90 second time limit even though all 4 overwings would still count as 50% of exits if the four Type I doors are blocked.

Not mumblings there, its true, one main benefit of the large doors is that an evacuation if handled correctly by crew (crowd control) will be able to flow through the doors at a rate of one passenger per second, overwings do not offer this as huge bottlenecks occur both at the exits and in the cabin as all the exits are in the same area of the aircraft. To add to that passengers would have to step out of the aircraft and either stay on the wing or come off the wing depending on the evacuation (water or land).

Phil
FlyingColours



Lifes a train racing towards you, now you can either run away or grab a chair & a beer and watch it come - Phil
User currently offlineDynamicsguy From Australia, joined Jul 2008, 887 posts, RR: 9
Reply 17, posted (5 years 5 months 2 weeks 5 hours ago) and read 4208 times:



Quoting MarkHKG (Reply 15):
And all for just 5 pounds!

My old boss used to work in the area and knew some of the people who ran that study. Apparently they were originally going to offer a larger sum, but discovered that 5 quid is really all the motivation people needed.

I wonder if any commercial airliner would pass the certification tests if they were done with such a motivation. I've seen footage of some of the above-mentioned study, and it was truly chaotic (and frightening).


User currently offlineMarkhkg From United States of America, joined Dec 2005, 960 posts, RR: 2
Reply 18, posted (5 years 5 months 2 weeks 3 hours ago) and read 4175 times:



Quoting Dynamicsguy (Reply 17):
with such a motivation

I always thought German people angrily shouting "RAUS RAUS RAUS" would be motiviation enough. Big grin

Seriously though, I think it has to be said that evacuation trials do generate motiviation of a different sort - a team mentality - to get off the plane as quickly as possible. I remember watching videos during the Boeing 777 trial in which one pax tries to help with opening one of the main doors - and has to be pushed back since he could have fallen out of the exit before the slide deployed. Then again, the same trial had one participant who was also so scared she refused to jump onto the slide...



Release your seat-belts and get out! Leave everything!
User currently offlineKELPkid From United States of America, joined Nov 2005, 6428 posts, RR: 3
Reply 19, posted (5 years 5 months 2 weeks 3 hours ago) and read 4170 times:



Quoting 2H4 (Reply 6):
Didn't Airbus gather a bunch of college students and offer some kind of monetary bonus if they all get out in time for the A380 tests? A stroke of brilliance, if you ask me. They could improve the times even further if a few hundred kegs of beer and swimsuit models were awaiting the college kids.

2H4

One of the ways I used to get flying money in college was to volunteer as a test subject for psychology dept. experiments  Wink (sure beat selling blood plasma...).



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineDynamicsguy From Australia, joined Jul 2008, 887 posts, RR: 9
Reply 20, posted (5 years 5 months 1 week 6 days 11 hours ago) and read 4038 times:



Quoting Markhkg (Reply 18):
Seriously though, I think it has to be said that evacuation trials do generate motiviation of a different sort - a team mentality - to get off the plane as quickly as possible.

That was sort of my point (though I didn't express it very clearly). An evacuation trial creates that sort of motivation - to work as a team to meet the goal. There's no genuine danger and there's no benefit for you to get out sooner than the next person in front of you, so everyone's working to get everyone off.

The 5 pound incentive provides a more realistic motivation - to get yourself out of the plane as quickly as possible for the individual rather than the team. I think the latter is more representative of a real life evacuation, and I'm not sure that a planeful of people working as individuals like that would get out in 90 seconds.


User currently offlineZappbrannigan From Australia, joined Oct 2008, 247 posts, RR: 0
Reply 21, posted (5 years 5 months 1 week 6 days 7 hours ago) and read 4018 times:



Quoting Dynamicsguy (Reply 20):
That was sort of my point (though I didn't express it very clearly). An evacuation trial creates that sort of motivation - to work as a team to meet the goal. There's no genuine danger and there's no benefit for you to get out sooner than the next person in front of you, so everyone's working to get everyone off.

The 5 pound incentive provides a more realistic motivation - to get yourself out of the plane as quickly as possible for the individual rather than the team. I think the latter is more representative of a real life evacuation, and I'm not sure that a planeful of people working as individuals like that would get out in 90 seconds.

Agreed. They all know they're in an evac test, and what sort of "behaviour" is expected. And I'm sure they all want to do the right thing by the aircraft manufacturer - i.e. help them pass the test wherever possible. In addition, there's no real stress - no actual fear of injury or death, and no fight-or-flight response.

In my experience in various other areas, when you add actual stress into the equation, to a group of subjects who are not trained in a specific response to that stress (unlike, say, a pilot responding to an emergency with a procedural, trained response to stimuli under stress), the results will be a lot more chaotic. I imagine offering cash to the first X percent off would generate a similar response.


User currently offlineDitzyboy From Australia, joined Feb 2008, 724 posts, RR: 1
Reply 22, posted (5 years 4 months 2 weeks 3 days 5 hours ago) and read 3430 times:

The 767s have dual-lane slides at both the doors and off-wing. The 737s have only single lane slides.

User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 23, posted (5 years 4 months 2 weeks 3 days 2 hours ago) and read 3430 times:

A search of the TCDS would have revealed the following:

The number and type of doors determines the maximum number of passengers .

255 for a 767-200 equipped with 2 pair Type A and 1 pair Type III doors.

290 for a 767-200/300 equipped with 2 pair Type A and 2 pair Type III doors.

290 for a 767-300 equipped with 3 pair Type A and 1 pair Type III doors.

351 for a 767-300 equipped with 3 pair Type A and 1 pair Type 1 doors.

375 for a 767-400


User currently offlineTod From Denmark, joined Aug 2004, 1732 posts, RR: 3
Reply 24, posted (5 years 4 months 2 weeks 3 days ago) and read 3430 times:

For other Type Certificate Data Sheets, see the link below:

http://www.airweb.faa.gov/Regulatory...keModel.nsf/MainFrame?OpenFrameSet

Tod


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