Boeing 737-800 Question (eyebrows thing)

[Leonvanos]

Hi,

after watching some pic's I got up with a big question.

The Boeing 737 series (300/400/500) have eyebrow above the pilot window.
But the 737-NG doesn't have them anymore, I tought. Cause I found 2 different examples.
First the Pegasus TC-APJ
Second the Sunexpress TC-SUH

Strange, but I am wondering why only these aircrafts have this extra thingy?

Anyone for an answer ????

greetz Leon van Os

[Delta12]

Im not sure, but it had something to do with maintenance costs.

From Airliners.net forum:

More info from the Boeing source.....the eyebrow windows were a hold-out from the 707/727 design and were originally intended for forward vision during a turn. Boeing's contention is that with TCAS technology and the recent 717 removal, that they may no longer be necessary, but wanted operator/pilot imput before proceeding. The production cut-in for no eyebrows was planned for the 3rd quarter this year. Eyebrow windows last about 7-9 years or 5000 hours and cost from $1800-2500 a piece. Weight savings would be approx. 25 pounds. I have not heard any more information whether this proposal will actually happen.

Oh btw I forgot the mention:

Airlines are also removing them, not only planes right from the factory leave without eyebrows.

Example:

PH-XRW 2003 with eyebrows: http://www.airliners.net/photo/Transavi ... 0355467/L/" onclick="window.open(this.href);return false;

PH-XRW last month without: http://www.airliners.net/photo/Transavi ... 1561700/L/" onclick="window.open(this.href);return false;

[Hurricane]

Hi,

after watching some pic's I got up with a big question.

The Boeing 737 series (300/400/500) have eyebrow above the pilot window.
But the 737-NG doesn't have them anymore, I tought. Cause I found 2 different examples.
First the Pegasus TC-APJ
Second the Sunexpress TC-SUH

Strange, but I am wondering why only these aircrafts have this extra thingy?

Anyone for an answer ????

greetz Leon van Os

Leon,

In fact all 737 have the eyebrows, it's up to the operator if he uses them (then there are windows installed; but due to intensive maintenance attention, most eyebrows are replaced with an sheetmetal repair (fillerplate) to solve this for good)

Guess PGT/QS have a reason for keeping them, although they are one of very few

Adios, Hurricane

[Bjorn320]

The eyebrow windows were originally installed for navigation aid, to navigate with the stars etc. But since GPS bacame more reliable and main navigation method the eyebrow windows were obselete.
In fact, on all new 737 NG aircraft the eye brow windows are not even installed anymore, if you look carefull the skin is completely flat when on retrofit aircraft you can see the blanking plates. The reason of replacing the eyebrow windows on older aircraft is indeed money, as the windows tend to delaminate under age they have toe be replaced in time, with a metal blanking plate this is not required anymore.

Plus it gives the aircraft a slightly better look...

[Key]

The eyebrow windows were originally installed for navigation aid, to navigate with the stars etc. But since GPS bacame more reliable and main navigation method the eyebrow windows were obselete.

Aren't you mixing this up with the fact USAF T-43's were used for celestial navigation training (among other things)? They had periscopic sextant stations to do this, according this page. The same page mentions the role of the introduction of GPS.
I would be surprised if stars were ever shot routinely through those 'eyebrows' in Boeing jet cockpits - though you never know. For instance, there may be situations where the stars you need are behind you, and therefore out of view through the eyebrows.

I think celestial navigation was last used widely in commercial aviation in the days of the great propliners - and they had special stations on top of the fuselage for this too. It was made redundant by the introduction of INS and the increase in available fixed navaids.
What did change too in commercial aviation, is the decrease in pure visual manoeuvring, due to high ILS availability, stricter procedures and simply more traffic. AFAIK, the main purpose of the eyebrows was to increase pilot visibility in turns. In light of instrument approaches being standard nowadays, with straight-in ILS being a major part of them, I can see a reason to get rid of the expensive eyebrows.


Erik