747-400 noisier than others?

[Philip76]

I've just returned from my first Australia-UK return flight and I reckon the Qantas 747-400s I flew in were far, far noisier than any other plane I've been on recently. I compared the noise level with the Virgin Blue 737 and a Jetstar A3something I flew on this weekend and the latter two planes were far quieter.

Now I know the engines are twice as numerous and probably a lot more powerful on the 747, but does that really make all the noise? When I stepped onto the 747 in London I noticed that the ventilation system was making a hell of a racket and this never subsided for the duration of the flight. In fact the engines were a minor addition to this. My noise cancelling headphones did a good job of lessening the irritation but they don't work miracles.

Should I be aiming for Airbus flights in future on long trips? Like Emirates perhaps? Has anyone else noticed that the 747s seem to be very noisy?

I was in 47K by the way.

 

[Kiwi Flyer]

Not at all. The upper deck is a nice cocoon.

 

[serfty]

Tend to be relatively quiet in first 4 or so rows as well ...

In the first months of my QP membership I flew almost solely on the old Qantas Airbus' A300B4s; being mainly in the last row I became quite used to the noise. One day, out of the blue, as a QP member I was upgraded to Busines class in row 4 and was quite surprised at the noise difference.

 

[NM]

In my experience, and certainly for anyone sitting forward of the engines, most of the noise in the cabin is from the air-conditioning and other passengers rather than from the engines.

AC noise varies by aircraft and if it was indeed making the racket you mention, then I suggest there was something lose inside the vents or ducts. Most of the AC noise is from the flow of air through the ducts and vents.

Note that Qantas 747 aircraft have individual movable air vents for each seat. These provide you with the ability to control your own flow of air, but do contribute to an increased air-flow noise when open. This is just due to the volume of air flowing through the constricted vent. You have the choice to turn them off if you want.

Some other airlines do not have individual personal vents (such as BA) on their aircraft. They have the air vent into the cabin from above the overhead lockers through larger vent grills. This results in less AC noise, but less individual control for the passengers.

I find my noise-isolation earphones (Shure E3) work way better than the best noise cancelling headphones.

 

[Philip76]

Yeah I'm convinced it was mainly ventilation noise, I was just amazed at how much noise could be made with air vents. There must be a very high speed/low cross section duct involved in creating the uniquely loud noise on the plane. And I guess some planes have different vent structures and therefore lower noise.

 

[NM]

Yeah I'm convinced it was mainly ventilation noise, I was just amazed at how much noise could be made with air vents. There must be a very high speed/low cross section duct involved in creating the uniquely loud noise on the plane. And I guess some planes have different vent structures and therefore lower noise.

Most of the AC noise comes from the airflow through the personal air vent located above each individual seat. When fully open, they probably have about a square centimetre space for the air to flow out. They are adjustable so the vent area varies down to zero. I find they are most noisy when almost closed and hence restricting the flow most.

So yes you will find less AC noise on a BA 747-400 flying the same route. But you won't have the personal air vent that you adjust for your own personal comfort. That is the trade-off.

So if travelling on a BA 747, you are reduced by one weapon on your personal defence coughnal against recliners .

 

[serfty]

... So if travelling on a BA 747, you are reduced by one weapon on your personal defence coughnal against recliners .

Also, don't forget the level of protection they afford against hygenically challenged fellow PAX.