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readytotaxi
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Cabin Air, From Which Direction?

Sun Feb 15, 2009 8:29 pm

The refreshing of cabin air, how does it enter the aircraft?
Does it enter at the front and work its way backwards?
Does that mean that First Class get the "Fresh air" first?  Big grin

It the air better by an exit door where it is cooler?  Confused
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avt007
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RE: Cabin Air, From Which Direction?

Sun Feb 15, 2009 8:33 pm

It enters from everywhere, through the vents above you, the floor level vents, all over the place. It then exits through the floor typically, and goes overboard through the outflow valves, typically at the aft pressure bulkhead. There's no advantage to sitting in any area in the cabin.
 
airbuster
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RE: Cabin Air, From Which Direction?

Sun Feb 15, 2009 9:33 pm

Depens on design but on my aircraft de outlets are all over place but the air is comming from the front though...so i believe the air pressure might be less at the end but correct me if i'm wrong, freshness of air shouldn't be any problem.

rgds

AB
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tdscanuck
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RE: Cabin Air, From Which Direction?

Sun Feb 15, 2009 11:36 pm



Quoting Readytotaxi (Thread starter):
The refreshing of cabin air, how does it enter the aircraft?
Does it enter at the front and work its way backwards?
Does that mean that First Class get the "Fresh air" first?

It varies a lot by aircraft. On a Boeing, it enters at the ceiling and flows down to the floor, through the vent grills by your feet into the area behind the cargo sidewalls, then out the outflow valve. Recirculated air is pulled from the mix bay (just behind the forward cargo compartment), mixed with fresh air from the packs, then distributed to all the a/c zones. So, within the passenger compartment, there's no fore/aft difference in air quality. Flight deck is a little different, and has their own dedicated air ducts.

People bitch a lot about air recirculation but, in addition to lowering the load on the packs and saving fuel, it's the only thing to humidify the air. If they ran 100% new air all the time, most people would have terrible headaches from dehydration, have much more problems with illness due to dry mucus membranes, and generally be more miserable than they already are.

I have heard complaints from flight attendants of poor air quality in the aisles of 777's, primarily due to the airflow hugging the signature interior walls and causing low air changeover in the aisles...I have no idea if this is true or not though.

Tom.
 
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HAWK21M
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RE: Cabin Air, From Which Direction?

Mon Feb 16, 2009 6:29 am

On Most aircraft, Air conditioning airflow enters the flight deck from louvers in the cockpit,normally equally distributed to circulate airflow evenly.In the Pax cabin its through the ceiling duct,above the windows in the ceiling corners or through the PSUs.most Pax air is 50% recirculated too.

regds
MEL.
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readytotaxi
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RE: Cabin Air, From Which Direction?

Mon Feb 16, 2009 4:55 pm

Many thanks for the insight people,  Smile
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avt007
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RE: Cabin Air, From Which Direction?

Tue Feb 17, 2009 3:37 am

The Dash 8 has floor level vents as well. There are many mods (well over a hundred service bulletins in ATA21) but some had a switch for the FA to select where the air came out of. Upper vents, floor vents, or both. The idea was to use the lower vents in winter, since hot air rises. Conversely, cold air settles, so the upper vent was better for summer ops.

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