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JEP
9th Apr 2002, 21:25
I hope, this is the right place to ask a this question.

How is the temperature in the passenger cabin adjusted / controlled og jet-airliners (B767, Airbus etc) ??

I have spend several nights on flights from West Africa to Europe on various european airlines flying B767 and A310 (no Boeing vs. Airbus issue), freezing under the thin blanket usually provided, and I wonder if anything could be done. I know several people who have been freezing during night flights too.

Is the cabin temp. controlled
-from the cockpit (by the pilots, who probably have no idea of the cabin comfort except from a temperature readout, as they are supposed to stay up front),
- a galley (by cabin crew) or
- is it a fixed setting.

I know it is impossible to adjust the cabin temp. to suit 2-300 people, but if you want to try - where is it done ??

trapped off
9th Apr 2002, 21:45
it is done from the cockpit by switches just above the F/O's head (757/767),there is no provision for adjustment by the cabin crew. some aircraft such as the 777 allow the cabin crew a small amount of adjustment, about 5 degrees as i remember.
Hope this helps.

basil fawlty
9th Apr 2002, 22:04
Cabin air temp is preset on the flightdeck and then regulated automatically. The correct temp is achieved by mixing hot engine bleed air with cold (1-2 deg C) air from the air conditioning packs. the cabin is usually divided into zones, with each zone having its own temp preselect. The temp range can be from a few degrees above freezing (set on freighters when carrying perishable goods) up to 40 degs C. The reason it is kept cool on nightflights is that the pax will then not keep demanding drinks from the cabin crew!

JEP
10th Apr 2002, 05:45
I thought it worked that way - thanks a lot.

I once told a cabin attendant I was cold, and after a while it became warmer. She might have asked the flight deck to add another degree on the thermostat.

Feret
10th Apr 2002, 10:57
There is a little more to cabin temp control than has been previously mentioned. I recommend that next time you have a long flight, especially at night, you opt for centre seating, on the 767 at least. Stay away from the sidewalls!

I can offer this info based on my experience with B762's. during cruise I used to run the mid and aft zones at 22 - 23 indicated initially then try to get the aft zone up to 24 when all down the back were supposed to be asleep. A quirk of the system on some aircraft (later, not earlier models) is such that the only way to increase the pack outlet temp when cold soaked is to crank up the cockpit temp and thus increase pack outlet temps which in turn gives warmer air down the back. Sometimes, heaven forbid, even "MANUAL" has to be used in lieu of "AUTO"! As a bonus though it means better cockpit service 'cause it is much warmer than the fwd galley and FA seating. The descent cabin temp control? Now there is a challenge! Anybody remember how well it all worked before that inflight low idle mod? Before everybody jumps in here with their own theories, we had access to the ECS page, on ground and inflight. That lets the cat out of the bag to those in the know! :-)

Just to sidetrack for a moment, years ago I had the experience of doing a few sectors with Boeing contract boffins on board who were troubleshooting an on-going random pack trip problem and I can tell you now that there is a lot more to the way the system operates than what's stated in the pilot's operating manual and maintenance manuals. Delve into the pack controllers etc and you will see what I mean. (FYI, a wire trace found that somebody had drilled through a loom!)

Go for it Ted!

Cheers.

GlueBall
10th Apr 2002, 18:39
In the tropics on the ground NO airplane has adequate cooling cabability. A comfort issue that Boeing and Airbus need to address. Maybe a supplemental pack just for use on the ground. Pax are not happy campers in a full cabin when temperature quickly creeps above 75F during boarding and taxi. Aircraft envirnmental control systems are deficient in places like BKK, DEL, DXB, MIA... when OAT is 90+ Fahrenheit. :(

basil fawlty
11th Apr 2002, 00:03
Feret,
I think JEP was asking for an explanation of the fundamental principles......the system schematic on every aircraft type is different, and has its own quirks with regards to practical day to day operation. Also, I think you'll find the sidewall on most types a bit on the cold side. I'm not being antagonistic honest, but you talk of the 767, I could go on about the 747, 727 & L1011, but it doesn't explain the way it works........

JEP
11th Apr 2002, 06:56
Mr. Fawlty (I just love that show - have seen the same episodes lots of times and they still almost kill me - danish and english humour are pretty much the same).

Acutually Ferets explanation helps a lot.
I have noticed the cold draught (hope it is spelled correct) comming down the side walls.

I just wanted to know, if it was just a matter of turning af knob a bit or there were some technical / operational explanation for it.
I understand that the various types might have a few individual quirks and as an enginner I can imagine the challenge it is to design a system that can maintain a comfortable temperature in an aircraft having all temperatures from -50 to +50 dec C on the outside.


Next time I will go for an aisle seat in the center section or ask the cabin crew if something can be done - knowing it might not be possible unless you create a tropic environment in the flightdeck forcing the pilots to fly in their underwear.. - it might not be a pretty sight and cause unbearable working conditions for the cabin attendants looking after the flightdeck ;).

Flight Detent
11th Apr 2002, 13:29
Hi all,
The aircon temp control on a Classic B747 is quite simple, the cabin is divided into 4 sections, plus the upper deck.
When the system is normal, in auto mode, the three aircon packs are controlled to provide conditioned air to all sections of the cabin at the temp that is required to keep the warmest section at the selected temperature. (ie, the coldest requirement)
Then, all the other sections add hot air as required to maintain their selected temperature.
So all the pack outlet temperatures will always be the same.
So, on the FEs panel, one of the five hot air additive valves, one to each section, will always be closed, indicating that is the section requiring the coolest conditioned air!
We even have recirculation fans to help 'mix' the cabin air.
Of course, in the 3-man cockpits, someone is always watching all the systems, and any slight adjustments can be made easily, just ask a crewmember, and they will pass the message on to the FE,
no problem!
The system works well, even at flight idle.

Did anyone hear of the B737-800 recently that had a double trip-off of the overheat control valves at TOD, (with the corresponding failure of the aircon/pressurization), and NOBODY noticed until the cabin altitude horn sounded on the way down, (with the cabin on the way UP), guess nobody was watching the shop!
Cheers

Feret
12th Apr 2002, 15:17
Basil.

Sorry I must have misread JEP's post. I thought he was after info on B767 and A310's. As the Airbus experience I have is A300, not A310, I opted to mention my experience with the B762. I could have offered info on many other types/models and how the systems work. Some are getting a bit hazy though. :(

Remember the bunk in crew rest (next to the unheated cargo door) on a B707 when it was cold soaked? That was COLD!

Like you I was a FE before retirement caught up with me.

Cheers.

Flight Detent
13th Apr 2002, 03:11
Hi Feret,
Sounds like you flew the A300 (B4) and the B762 in Oz, as an FE.
Cheers

Jetlagged
13th Apr 2002, 21:11
Temp control for Pax on any aircraft is a bit of an art and needs to be moniterd and adjusted for the following circumstances
Are the Cabin crew doing a service, yes =slightly colder, at night the cabin crew request colder temps whilst they do the service because they get hot running around, but the temp must then be increased when the service is over and the pax are asleep.
Is it a daylight flight ?. pax dont sleep=slghtly colder
is the temp sensor next to a light, (dont laugh A300 actually had this problem), =slightly colder or manual control. (need feedback).
I too am amazed at how cold the cabin is regulated on some of these aircraft. many pax actually catch a cold during the flight. a comfortable night cabin sleep tempreture I was taught is 25-26 degrees (c). jeez guys warm it up a bit at the back after the service, and yes I am a Flight Engineer on classics

basil fawlty
14th Apr 2002, 16:28
No probs, Feret.
All the best to you for your retirement.
Cheers.:)

GoodToGo!
16th Apr 2002, 07:50
Feret,
I remember the aircraft, I remember the defect, I remember doing the wire trace with the TDR, I remember finding the drilled through loom in the fwd Cargo Compt. and I remember spending a f***ing-long time doing all the wire splicing!!!!
To this day I would love to know who the meathead who did it was....


Cheers!
GTG! :D

Fil
20th Apr 2002, 16:56
1. Temperature normally set at moderate setting by flight crew.

2. Temp constantly tweaks upwards due continual @I'm cold messages from the cabin crew (female).

3. Temp reduced when customers complain of sauna like temperatues via cabin crew (male)

4. Goto 2.



So in reality the temperature in the cabin usually whatever the cabin crew want it to be.

Barbers Pole
25th Apr 2002, 23:25
We have a naughty Flight attendant who will march into the cockpit with her breasts out & says "guess what the problem is down the back" !! :)

great lady....

BobTheRocker
28th Apr 2002, 08:38
Jetlagged, reference your quote on this subject:

"many pax actually catch a cold during the flight."

The Common Cold is a virus and one is not able to "catch a cold during the flight" from being cold. The reason so people catch colds while flying is dud to the fact that air in an aircrafts cabin is recycled and recirculated several times. Therefore anyone who has the airborne common cold virus will indeed more than likely pass it on to other passengers.

P.s. I realise this is not a medical forum, just couldn't resist!

Jetlagged
10th May 2002, 18:59
Well spoted BobTherocker, now see if you can spot the obvious mistake, clue (its technical in nature).;)