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Reason For The 737 Higher Front Windows?  
User currently offlinePs76 From , joined Dec 1969, posts, RR:
Posted (7 years 6 months 2 weeks 4 days 16 hours ago) and read 5785 times:

Was just wondering what the reason was for the higher windows in the Boeing 737. What would a pilot need to see from the perspective - Maybe for light/general visibilty? Traffic?

40 replies: All unread, showing first 25:
 
User currently offlineCanadianNorth From Canada, joined Aug 2002, 3389 posts, RR: 9
Reply 1, posted (7 years 6 months 2 weeks 4 days 16 hours ago) and read 5790 times:

They are called "eyebrow windows" I believe.

The original nose design of the 737 is basically the same as the 727, which is basically the same as the 707. Back in the day when the 707 was brand new, these windows were useful for spotting traffic, and they also could potentially help with weather, and if things were really bad help with navigation.

However, with todays technology the 737NG can do all that via computer faster, easier and more reliable. Thus, they have been eliminated on 737s currently in production, and it is an option to remove them on 737s made with them.

707:

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727:

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737 with:

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737 without:

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CanadianNorth



What could possibly go wrong?
User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 2, posted (7 years 6 months 2 weeks 4 days 15 hours ago) and read 5775 times:

Good for keeping an eye on the runway during turns in a visual landing pattern, I'd say... until someone who has flown'em chips in and says otherwise.

Their main purpose seems to be storing newspapers though.  Wink



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineAero145 From Iceland, joined Jan 2005, 3071 posts, RR: 21
Reply 3, posted (7 years 6 months 2 weeks 4 days 14 hours ago) and read 5705 times:

Quoting CanadianNorth (Reply 1):
They are called "eyebrow windows" I believe.

That is true...

I find it however funny that the new 737s or old modified 737s which do not have the eyebrow windows don't get my attention, they look somehow normal without them.

What do you think, guys?


User currently offlineCovert From Ghana, joined Oct 2001, 1450 posts, RR: 2
Reply 4, posted (7 years 6 months 2 weeks 4 days 9 hours ago) and read 5614 times:

It made it easier to navigate by the stars in the 707 and 727, now it just lets too much light in.


thank goodness for TCAS !
User currently offlineMohavewolfpup From , joined Dec 1969, posts, RR:
Reply 5, posted (7 years 6 months 2 weeks 4 days 8 hours ago) and read 5588 times:

how are they a maintenance issue? I think I saw a post in a thread they have maintenance issues. leaky? or just antiqued?

sadly, if I was a pilot I would mourn the loss of being able to see stars out them, but I am really cheesy and like stuff like that.

nothing beats being at 37,000 feet hauling 100+ people to their futures, destinations,marriages,family,vacations,hopes and dreams, etc and looking at stars wizzing by at 500 mph.

okay, i'll cut the sap :p

it also shows how much more reliant we are becoming on computers also to do the work of what pilots had to do in the past manually (finding the north star)


User currently offlineN231YE From , joined Dec 1969, posts, RR:
Reply 6, posted (7 years 6 months 2 weeks 4 days 8 hours ago) and read 5576 times:

Quoting Mohavewolfpup (Reply 5):
how are they a maintenance issue? I think I saw a post in a thread they have maintenance issues. leaky? or just antiqued?

The eyebrow windows added "unnecessary" weight, and I believe the maintenance issues included lamination problems (?).


User currently offlineN243NW From United States of America, joined exactly 11 years ago today! , 1624 posts, RR: 20
Reply 7, posted (7 years 6 months 2 weeks 4 days 7 hours ago) and read 5557 times:

Quoting CanadianNorth (Reply 1):
Thus, they have been eliminated on 737s currently in production

 checkmark 

Quoting CanadianNorth (Reply 1):
and it is an option to remove them on 737s made with them

 checkmark 

Same story with the 717. Is there an option offered [yet] from Boeing to fill existing windows with this model as well? Or is the demand (fleet size) too small to make such a retrofit cost-effective?


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-N243NW Big grin



B-52s don't take off. They scare the ground away.
User currently offlineNonfirm From United States of America, joined Sep 2005, 434 posts, RR: 0
Reply 8, posted (7 years 6 months 2 weeks 4 days 3 hours ago) and read 5517 times:

Quoting Mohavewolfpup (Reply 5):
how are they a maintenance issue?

The removal of the eyebrow windows is very helpful for maintenance.First off there are four less windows that need to be attended to also they have a problem with delamination.If the delam is out of limits then they need to be replaced.I have found with our fleet of 737-400's that almost all of the eyebrow window's are on defferal for delam also with the hud's installed on the Capt's side they are almost useless.As stated most of the time they are blocked anyway with window shade's or paper.  airplane 


User currently offlineMohavewolfpup From , joined Dec 1969, posts, RR:
Reply 9, posted (7 years 6 months 2 weeks 3 days 21 hours ago) and read 5439 times:

Quoting Nonfirm (Reply 8):

what's the worry with the delam? decompression issues, or just visual issues?

and how are they blocked off? just a metal plate welded in?


User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 10, posted (7 years 6 months 2 weeks 3 days 21 hours ago) and read 5431 times:

Quoting FredT (Reply 2):
Good for keeping an eye on the runway during turns in a visual landing pattern, I'd say

That would sure be a diving turn to keep the runway in sight out the eyebrow windows!  eek 

I like the no eyebrow look on the 73's.



Any views shared are strictly my own and do not a represent those of any former employer.
User currently offlineAero145 From Iceland, joined Jan 2005, 3071 posts, RR: 21
Reply 11, posted (7 years 6 months 2 weeks 3 days 21 hours ago) and read 5426 times:

Quoting Mohavewolfpup (Reply 9):
just a metal plate welded in?

Probably...


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User currently offlinePilotaydin From Turkey, joined Sep 2004, 2539 posts, RR: 51
Reply 12, posted (7 years 6 months 2 weeks 3 days 15 hours ago) and read 5352 times:

Quoting FredT (Reply 2):
Their main purpose seems to be storing newspapers though.

bingo, a klenex box fits RIGHT into the damn thing, and i can pull one out during meal times and i love it LOL

it's so annoying though when the sun is high up, it really bakes you sometimes



The only time there is too much fuel onboard, is when you're on fire!
User currently offlineNonfirm From United States of America, joined Sep 2005, 434 posts, RR: 0
Reply 13, posted (7 years 6 months 2 weeks 3 days 9 hours ago) and read 5300 times:

Quoting Mohavewolfpup (Reply 9):
what's the worry with the delam? decompression issues, or just visual issues?

and how are they blocked off? just a metal plate welded in?

The problem with the delam is when it grows beyond the limit from the corners of the window and the sides you are only allowed a few inches if it's beyond then you need to replace the window.Here is the link of the mod.

RE: 737 Eyebrow Mod (by ZANL188 Nov 26 2006 in Tech Ops)?searchid=174667&s=737+eyebrow+window#ID174667  airplane 


User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 14, posted (7 years 6 months 2 weeks 3 days 7 hours ago) and read 5270 times:

This all may have been mentioned to some degree, but I will condense it:

- Eyebrow windows were originally installed so a sextant could be used...

- The maintenance bonus comes from the elimination of a heated piece of glass...

- The new structure keeps the cockpit cooler (huge for glass tube a/c), is lighter, stiffer, more fatigue resistant, and completely eliminates a part number.

Good deal all around!

(And if you are a manufacturing guy, the last thing you do is cut out a piece and then weld in a blank...you just eliminate the stamp that cuts out the window in the first place!!!)

[Edited 2007-01-09 06:07:38]

User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 15, posted (7 years 6 months 2 weeks 3 days 7 hours ago) and read 5259 times:
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Quoting EssentialPowr (Reply 14):
- Eyebrow windows were originally installed so a sextant could be used...

Are you sure about that? If that is indeed the case, why would the VC-137C have had an entirely separate sextant port installed?

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2H4





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User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 16, posted (7 years 6 months 2 weeks 3 days 6 hours ago) and read 5250 times:

B/c a VC 137C uses celestial as a secondary nav to this day... not so the 737, and a dedicated port is not nec in the first place if you've ever used a sexant...an eyebrow window will work, but even from the 707 days Boeing projected that electronic, ground based nav eliminated celestial nav. Old habits die hard in the mil and the Nav in particular...

User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 17, posted (7 years 6 months 2 weeks 3 days 1 hour ago) and read 5203 times:

Quoting N231YE (Reply 6):
The eyebrow windows added "unnecessary" weight, and I believe the maintenance issues included lamination problems (?).

Don't forget cockpit noise reduction.
regds
MEL



Think of the brighter side!
User currently offlineBAe146QT From United Kingdom, joined Sep 2006, 996 posts, RR: 0
Reply 18, posted (7 years 6 months 2 weeks 3 days ago) and read 5193 times:

Quoting HAWK21M:
Don't forget cockpit noise reduction.

Forgive me if this has been asked before, but it strikes me that a thick piece of glass would be a better sound insulator than a few mm of sheet metal and a plastic facade.

So does the noise reduction come from that fact that you're losing four panel lines and a row of rivets/bolts?



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User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 19, posted (7 years 6 months 2 weeks 2 days 23 hours ago) and read 5175 times:

Quoting BAe146QT (Reply 18):
So does the noise reduction come from that fact that you're losing four panel lines and a row of rivets/bolts?

Addition of Vortex generators too.
regds
MEL



Think of the brighter side!
User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 20, posted (7 years 6 months 2 weeks 2 days 15 hours ago) and read 5119 times:

Quoting BAe146QT (Reply 18):

So does the noise reduction come from that fact that you're losing four panel lines and a row of rivets/bolts?

Absolutely; removal of the window results in a more continuous piece of metal. Any seal b/t a window and the frame will eventually leak somewhat, and therefore hiss, over time...


User currently offlineKELPkid From United States of America, joined Nov 2005, 6343 posts, RR: 3
Reply 21, posted (7 years 6 months 2 weeks 2 days 14 hours ago) and read 5102 times:

Quoting Mohavewolfpup (Reply 9):
and how are they blocked off? just a metal plate welded in?

Although it is now possible to weld aluminum (TIG and MIG), I'd put money on the mod being a sheet of aircraft-grade aluminum large enough to cover the hole and then some, placed inside the pressure vessel, and then rivited from the outside. Any mechanics want to comment on this? Also, do the interior panels receive an update at the same time to a part without the window cutouts?



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineZANL188 From United States of America, joined Oct 2006, 3500 posts, RR: 0
Reply 22, posted (7 years 6 months 2 weeks 2 days 14 hours ago) and read 5090 times:
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Quoting EssentialPowr (Reply 16):
B/c a VC 137C uses celestial as a secondary nav to this day... not so the 737, and a dedicated port is not nec in the first place if you've ever used a sexant...an eyebrow window will work, but even from the 707 days Boeing projected that electronic, ground based nav eliminated celestial nav. Old habits die hard in the mil and the Nav in particular...

The VC-137Cs are all in museums, modded to another type, or scrapped now so they are certainly not using celestial nav to this day.

So if somebody were to use the eyebrow window with a sextant how would that work exactly? If the pilot stood on the floor the yoke would be poking him in the groin -- I guess he could stand on the seat and do it that way. Just seems awkward to me.


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edit: add photo

[Edited 2007-01-09 22:50:22]


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User currently offlineN231YE From , joined Dec 1969, posts, RR:
Reply 23, posted (7 years 6 months 2 weeks 2 days 12 hours ago) and read 5043 times:

Quoting EssentialPowr (Reply 20):
Absolutely; removal of the window results in a more continuous piece of metal. Any seal b/t a window and the frame will eventually leak somewhat, and therefore hiss, over time...

Since the noise seems to be caused by some sort of disturbance in the airflow, would the removal of the window provide some sort of performance benefit?


User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 24, posted (7 years 6 months 2 weeks 2 days 10 hours ago) and read 5019 times:

Quoting ZANL188 (Reply 22):
The VC-137Cs are all in museums, modded to another type, or scrapped now so they are certainly not using celestial nav to this day.

The point is that a lot of mil a/c had them, to include P3s which are still on active service w/ the NAV.

Quoting ZANL188 (Reply 22):
So if somebody were to use the eyebrow window with a sextant how would that work exactly? If the pilot stood on the floor the yoke would be poking him in the groin -- I guess he could stand on the seat and do it that way. Just seems awkward to me.

Uhh... remaining seated?

Quoting N231YE (Reply 23):
Since the noise seems to be caused by some sort of disturbance in the airflow, would the removal of the window provide some sort of performance benefit?

Absolutely. Aside from the fact that the window is heavier than the blank aluminum that was there in the first place, any time a discontinuity in the a/c's skin is eliminated, the result is smoother airlflow. In short, eliminating the window enhances perfromance by:

1. reducing weight
2. " complexity, as those windows are heated and share a temp controller as well as have requisite wiring/circuit breakers/etc
3. reducing/removing spare parts from the inventory
4. reducing the build cost
5. smoother airflow over the nose section


25 N231YE : I see...I knew about the weight issues for the window itself, but did not realize the associated systems/items and parts inventory. Since nobody uses
26 RSBJ : I fly a 707 (KC-135) and 737's and I have to say I have never once in thousands of hours used the eyebrow windows; even in tight visual patters or for
27 Post contains images HAWK21M : You sure do.When you use the Newspaper to blank out the light. Amazing how these Windows are always Blanked out with Paper to stop the light. regds M
28 JBo : I'm not sure if Boeing would offer an eyebrow-removal program for the 717 as well. It appears the window design on the 717 (and DC-9, MD-80, et al) i
29 Gr8Circle : The old 707's used to have a sextant in the same position as shown in the pic of the VC-137C abvove...I have personally seen them being used during f
30 Post contains links and images KELPkid : I'm familiar with the Mark III Sextant, and it's usage in flight would depend upon a clear shot of the horizon and the aircraft's eyebrow would have
31 Post contains images ZANL188 : Not particular what star you're shooting then are you?
32 Post contains images N243NW : Thanks for the input. It makes perfect sense as far as costs are concerned. -N243NW
33 EssentialPowr : Out of an approx 6" x 10" window? Not a lot of field of view in the first place!
34 ZANL188 : Hence my point that using the eyebrows for sextants is rather awkward and unlikely.....
35 Post contains images 2H4 : That's what I was thinking.... So, forget about the reason for the installation of tiny eyebrow windows on the Boeings.....why the heck were tiny eye
36 Post contains images ZANL188 : Wasn't the JetStream originally a military design? In which case it would be easy to figure why they were removed for the commercial variants -- They
37 LongHauler : Canadi>n's arctic B737s were equipped with an Astro Compass, similar in use to a sextant. This was stored under the second jump seat behind the Captai
38 Post contains images 2H4 : Here's one in a B-25 cockpit: 2H4
39 Post contains images JetMech : The windows that I have seen blanked have always been on 747's. Most window cutouts in the pressurised skin will be re-inforced with a window forging
40 HAWK21M : Anyone aware of the entire Job of this Mod kit. regds MEL
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