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Exit Limits on 737 and A320

Posted: Mon Mar 15, 2021 6:39 pm
by VirginFlyer
In the thread Boeing nears 737 MAX order from Southwest worth billions, there is some discussion about exit limits for passenger seating:
DenverTed wrote:
I believe 150 seats needs two over wing exits per side. If they disable one, they can seat 149. The potential benefit being, using the space for a seat where it is missing on the -8, and potentially maintenance savings on the exit.
Just speculating at the configuration.
The -7 is 154" shorter than the -8. Five rows at 32" is 160". An extra 6" to use somewhere on the -7, like have the last row have extra pitch and recline.
175 seats minus five rows is 145 seats. Add in two missing exit row seats is 147.

barney captain wrote:
Everything we've heard is it will seat 150 with 3 FA's. I don't think there's any requirement for the number of overwing exits per side, just the time to evacuate by whatever means.

DenverTed wrote:
Based on observation of the exit limits of the 737-300,-600,-700 at 149, and I think the 720 with one overwing at 149, I just assumed it was some type of prescriptive rule. Same with 179 or 189 for double over wing, 239 for a 757. Kind of a mystery to me as to where those numbers come from or why they were chosen.

orlandocfi wrote:
Your observations are correct. The high-density A319, for example, has 4 over wing exits to allow it to seat up to 160. I think the -7 will max out at 172. The numbers are based on the type and quantity of exit door, as well as distance to exits. Not sure how they get to the exact numbers but I’m sure it makes sense to them!

VirginFlyer wrote:
The rule is in the aircraft certification requirements under FAR Part 25: https://www.ecfr.gov/cgi-bin/text-idx?n ... .1.25_1807

(g) 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

With two pairs of Type A and one pair of Type III, you get a limit of 55+55+35=145 seats. A second pair of Type III exits then gives 180 seats (and actually that poses a question - where does 189 for the 737-800 come from?)

Armadillo1 wrote:
2*110 = already 220

Polot wrote:
The 737 main exits are Type I. I’m not sure there is any narrow body with Type A exits, those are usually the main exits on wide bodies.

Armadillo1 wrote:
https://aviation-safety.net/airlinesafety/exits/exit.php?type=103-8
https://aviation-safety.net/airlinesafe ... type=022-0

still something unclear about 738

VirginFlyer wrote:
D’oh! I meant to type Type C. But if they are Type I, I’m not sure how the numbers add up: 45+35+45=125 for a 737-300/700?


Is anyone able to explain how these exit limits are applied to get the maximum seating capacities of the A320 and 737 families? I can’t make heads or tails of where 189 seats on a 737-800 might have come from.

V/F

Re: Exit Limits on 737 and A320

Posted: Mon Mar 15, 2021 9:18 pm
by Woodreau
I don't know anything about 737s, but our 319s are limited to 145 instead of 156 because of life raft considerations.

Re: Exit Limits on 737 and A320

Posted: Mon Mar 15, 2021 9:24 pm
by unimproved
IIRC, the "service" side has smaller doors than the pax side.

Re: Exit Limits on 737 and A320

Posted: Wed Mar 17, 2021 5:22 am
by zeke
VirginFlyer wrote:

Is anyone able to explain how these exit limits are applied to get the maximum seating capacities of the A320 and 737 families? I can’t make heads or tails of where 189 seats on a 737-800 might have come from.

V/F


If you look at the EASA TCDS explanatory notes it may help answer your question

Image

From https://www.easa.europa.eu/sites/defaul ... S%2011.pdf

Re: Exit Limits on 737 and A320

Posted: Wed Mar 17, 2021 10:17 am
by VirginFlyer
zeke wrote:
VirginFlyer wrote:

Is anyone able to explain how these exit limits are applied to get the maximum seating capacities of the A320 and 737 families? I can’t make heads or tails of where 189 seats on a 737-800 might have come from.

V/F


If you look at the EASA TCDS explanatory notes it may help answer your question

Image

From https://www.easa.europa.eu/sites/defaul ... S%2011.pdf

Thank you very much Zeke, appreciate it

V/F