View Full Version : Cockpit noise

1st Sep 2010, 16:26
Hey guys!

I just have a question that had been haunting my mind last couple of weeks!

All boeing 737 NGs are fited with 10 tiny Vortex Generators near the front windshield and on the nose (not the aft VGs!). And Boeing says it reduces cockpit noise.

Another friend of mine said, it is to energize the airflow which may disturbe by the gap of the radome hing area.

Will anybody know what is the story behind this 10 VGs? and technically how it will reduce the cockpit "noise" ?. I appriciate a very discriptive one :)

Thank a lot!


3rd Sep 2010, 12:03
I also was advised those vortex generators immediately ahead of the #1 windshields was for noise reduction.
I assumed the parked wiper arms/blades were the main cause in that area.
Also, the deletion of the eye-brow windows happened at the same time in the production line.


3rd Sep 2010, 13:44
It's said they are installed for noise reduction. However not all 737NG's are fitted with the vortex generators. I believe it only makes a small difference, the 737 cockpit is just very noisy...
I don't exactly know the technicalities behind it, but I assume that the VG's guide the airflow away from the wipers and streamlining the airflow, creating less parasite drag and thus less noise.

3rd Sep 2010, 14:04
Warning Systems (http://www.b737.org.uk/warningsystems.htm#Noise_Levels)

Half way down - with my screen at least :)

3rd Sep 2010, 15:39
Thanks guys. I know it's kind of hard to understand exactly.

I don't get the point those VGs could reduce the noise of airflow hit the shield at the cruise velocity.

and also those VGs will energize the airflow, which makes the velocity further at a high number. Hense it will hit the shield at a more higher speed!.

I didn't know not all NGs are not fitted with these VGs, thanks for you info.

anyhow if really it reduces cockpit noise, why other airliners do not adopt that? is it Beoing patient?

I am still struggling to find the answers! but always end up with only with questions! :)

Thank guys



3rd Sep 2010, 16:40
my hearing has been deteriorating since my first flight~
5 years flying(riding on the right) cause my left ear hearing is worse than my right side one.
because the right ear is covered by the headset, the left ear is exposed to the open cockpit air( for the crew communication and aural warning).
does anyone has the same situation as me ???

3rd Sep 2010, 17:02
Red Herring. Boeing always caters to pilots, but 3dB? Those generators keep FOD off the glass, and bugs. Who wants to graduate to the Guppy and still fly a "BugSmasher"?

bear, disturber of airborne myth

3rd Sep 2010, 17:17
bearfoil, just for you. If nothing else you'll get to see a line drawing of an Armstrong Whitworth Argosy.

Considerations about forward fuselage design (http://www.scribd.com/doc/27851188/Considerations-about-forward-fuselage-design)

3rd Sep 2010, 17:20
Cant say the insect deflecting works well either. Both effects are rather small, but noticeable if you fly both types of NG (with and without the VGs).

As for your ear problems, i would suggest a good filter plug and/or a noise cancelling headset worn on both ears.

3rd Sep 2010, 17:52
Thanks foget! your link gave me lost of answers! that more than just enough! appriciate thisa lot! cheers!

Code 0

3rd Sep 2010, 18:06
thanks , denti
i`ll try~

6th Sep 2010, 06:20
I've personally always wondered what the 707 front office noise was like relative to the 732 and 737NGs, never having had the opportunity to see for myself.

6th Sep 2010, 09:50
I find the difference between 9 year old NGs and recently delivered models is pretty significant in terms of noise level. The VGs do their part especially during high speed flight while the redesigned fresh air ducting takes away a lot of the white background noise. Amazing how some old planes become almost silent with the recirculation fans off...

6th Sep 2010, 13:39
one of my college sometimes doing this (turn off the recirculation fan during flight which i never done)
he said it`s quite quiet~
and pull out one of the CB of the standby attitude indicator drum vibraration. it also reduce the cockpit noise:ooh::ooh::ooh:
i agree with the noise reduction, but i will never do this!

6th Sep 2010, 15:30
On the -800 we usually have the nr. 1 recirc fan off below FL100, on the -700 the only one, only downside is slightly higher fuel burn. Makes for a much less noisy cockpit environment. Thank god the good ol' standby altimeter vibrator is not an issue anymore with the ISFD, that was kinda annoying and some CPTs pulled the CB for that which i never really liked as there is a reason for the vibrator, however noisy it is.

galaxy flyer
6th Sep 2010, 15:49
You want to know noisy--ride in the front end of the old 727 at m.84! That was NOISE.


6th Sep 2010, 15:57
oooops, thanks denti
it`s the stby altimeter~

13th Sep 2010, 16:46
After 2 weeks I found the answer for this.

VGs over the nose of 737NGs are to reduce the cockpit noise. These VGs are totally different to the VGs you find near control surfaces.

these cockpit noise reduction VGs are blunt bodies. they blick the airflow so it reduces the local velocity near the windshield, hense the airflow hit the no.1 windshileds is slowed.

it is obvious that these 10 VGs produce some sort of drag but I guess it is neglegible.

Anyhow I havent come across anyother aircraft fixed with these kind of VGs for voice.



13th Sep 2010, 17:32
..... blick the airflow .....Sorry? :confused: