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Some ?s About Emergency Exits  
User currently offlineAA777223 From United States of America, joined Feb 2006, 1235 posts, RR: 6
Posted (4 years 12 months 2 days 18 hours ago) and read 2285 times:

I am confused about exit designs and the regulations that govern them. For example, due to the recent CO 762 debacle, I got to llok at some photos.

The 762 has two main exits and one window exit on each side of the aircraft. This is the same as a 737-700, which in CO guise only seats about 125 people. The 762 seat 174 people. The 739 seat 173 people, 1 person less than the 762, yet it has 2 mian exits and 2 window exits per side, with most 739s featuring an extra main exit. (Why does CO have fewer exits on their 739s?)

Another example is AA 763s featuring two main and two window exits to evacuate 225 people, while their 738s, with the same xit configuration only have to evacuate 148 people. The 777 seat 224 people, one less than the 763, but it has 4 main exits per side.

Anyway, I know the 762 is a much more premium heavy aircraft, etc., but in an emergency, you have to get the same number of people out of fewer exits as compared to other aircraft. I think you see my point. More people, same number of exits, what are the rules? How do airlines get some aircraft with fewer exits certified (i.e. CO 739) or more exits certified (i.e. easyjet A319...I think).

Any info is appreciated.


Sic 'em bears
9 replies: All unread, jump to last
 
User currently offlineGT4EZY From United Kingdom, joined Dec 2007, 1781 posts, RR: 3
Reply 1, posted (4 years 12 months 2 days 18 hours ago) and read 2269 times:

Although I may be wrong, it has something to do with the maximum number of passengers per exit. What you also have to remember is that the 762 main exits have dual lane slides thus making evacuation quicker.

Everyone uses the Easyjet A319 (4 overwing exits) as a precedent but didn't Britannia have to have 4 overwings certified for charter configuration of the 762? It's capacity was 280!



Proud to fly from Manchester!
User currently offlineBMI727 From United States of America, joined Feb 2009, 15719 posts, RR: 26
Reply 2, posted (4 years 12 months 2 days 18 hours ago) and read 2219 times:



Quoting AA777223 (Thread starter):
More people, same number of exits, what are the rules?

The type of exit also makes a difference. The 762 has larger front and rear exits than a 737 so that helps. Part of it is how the plane is made. Extra exits have been added, but it is rare to deactivate an exit for a less dense arrangement.

An example of that would be CO's 739ERs, which of course have the additional exit, but it is not activated since they do not have extra seats.



Why do Aerospace Engineering students have to turn things in on time?
User currently offlineAA737-823 From United States of America, joined Mar 2000, 5731 posts, RR: 11
Reply 3, posted (4 years 12 months 2 days 12 hours ago) and read 1997 times:

Widebody aircraft feature "double-wide" exits. Hence the 747 only needs 5 sets of doors- they're actually quite large.
That said, something that the crash of Continental's 737-500 in Denver last winter taught us is that WE NEED MORE EXITS. People couldn't get out fast enough, as half of the exits were literally blocked by a continuous fireball. Now, the Fed requires half of the airplanes' exits be inop for evac certification, but still.... that's not a pretty picture.

Anyhow, something a lot of people don't know is that narrowbody exit doors are actually quite small. You can't walk through a 737 R1 door without stooping, and the same door on the DC-9 / MD-80 series is more of a window to open on a hot day.

Quoting BMI727 (Reply 2):
but it is rare to deactivate an exit for a less dense arrangement.

Not really; a lot of 747s had their overwing exits deactivated in the 1980s. United deactivated a bunch of 727 doors as well.


User currently offlineWNCrew From United States of America, joined Jun 2006, 1444 posts, RR: 10
Reply 4, posted (4 years 12 months 2 days 12 hours ago) and read 1989 times:



Quoting AA737-823 (Reply 3):
Not really; a lot of 747s had their overwing exits deactivated in the 1980s. United deactivated a bunch of 727 doors as well.

No, it was indeed rare and NOT common, there were not very many airlines which exercised this option.



ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
User currently offlineViscount724 From Switzerland, joined Oct 2006, 24906 posts, RR: 22
Reply 5, posted (4 years 12 months 2 days 11 hours ago) and read 1978 times:

Some 762s sold to charter carriers with very high-density seating, sometimes 8-abreast in Y class, were built with 2 overwing exits to meet evacuation requirements. Examples below:


View Large View Medium
Click here for bigger photo!

Photo © Jordi Grife - Iberian Spotters
View Large View Medium
Click here for bigger photo!

Photo © Giovanni Verbeeck



User currently offlineMarkHKG From United States of America, joined Dec 2005, 960 posts, RR: 2
Reply 6, posted (4 years 12 months 2 days 11 hours ago) and read 1933 times:

This is mostly answered in FAR 25.807

http://rgl.faa.gov/Regulatory_and_Gu.../rgFar.nsf/FARSBySectLookup/25.807

Type and number required. The maximum number of passenger seats permitted depends on the type and number of exits installed in each side of the fuselage. Except as further restricted in paragraphs (g)(1) through (g)(9) of this section, the maximum number of passenger seats permitted for each exit of a specific type installed in each side of the fuselage is as follows:

Type A....................................................................... 110
Type B....................................................................... 75
Type C........................................................................ 55
Type I......................................................................... 45
Type II........................................................................ 40
Type III....................................................................... 35
Type IV..................................................................... 9



Release your seat-belts and get out! Leave everything!
User currently offlineWNCrew From United States of America, joined Jun 2006, 1444 posts, RR: 10
Reply 7, posted (4 years 12 months 2 days 11 hours ago) and read 1911 times:



Quoting AA737-823 (Reply 3):
That said, something that the crash of Continental's 737-500 in Denver last winter taught us is that WE NEED MORE EXITS. People couldn't get out fast enough, as half of the exits were literally blocked by a continuous fireball.

The NTSB has not stated the need for more exits as a result of this accident. In fact it appears the exits were perfectly acceptable as everyone got out alive. Half of the exits were indeed blocked, but that's the point of the requirement of only half available exits during a certification evacuation drill. If anything, the CO accident showed us that even with a raging fire and unfavorable outside conditions, proper FA training, effective commands and the minimum compliment of exits, a safe evacuation of all pax is possible, in other words... our hard work over the years developing these rules and regs has worked!

Remember, the more exits, the more restricted the interior configuration of rows/seats and also the possible requirement for more crew depending on the exit type, location, and operation.



ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
User currently offlineAA777223 From United States of America, joined Feb 2006, 1235 posts, RR: 6
Reply 8, posted (4 years 12 months 1 day 19 hours ago) and read 1719 times:

I have flown quite a bit in my day, and I guess I just never really noticed the size differences of widebody vs. narrowbody large, medium, and small exit doors beyond the function of the obviously larger fuselage barrels. Thanks for the insight.


Sic 'em bears
User currently offlineBMI727 From United States of America, joined Feb 2009, 15719 posts, RR: 26
Reply 9, posted (4 years 12 months 1 day 18 hours ago) and read 1664 times:



Quoting AA737-823 (Reply 3):
Now, the Fed requires half of the airplanes' exits be inop for evac certification, but still.... that's not a pretty picture.

I think that this rule has been in place for longer than that.



Why do Aerospace Engineering students have to turn things in on time?
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