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25F
20th May 2004, 22:41
Just talked to a friend who flew Ryanair to Treviso last night, and she said that the cabin temperature was low enough to prompt complaints from the passengers. Is there an official minimum? Is a warm cabin another "frill" that has been done away with?

Engineer
21st May 2004, 00:15
Would not happen if there was a FE on board :ok:

Globaliser
21st May 2004, 00:23
Biscuit Chucker: failing that, grab an extra blanket before some other f**er takes them all..Blankets on Ryanair? I like the idea. :D

Anyway, can someone with technical knowledge comment on this: isn't it the cooling (ie air conditioning) which is energy-consuming, so that fuel would actually be saved by letting warmer air into the cabin?

BOAC
21st May 2004, 07:11
25F - as said above, it requires liaison between pax/cabin crew and flight deck. Flight deck indications are two-fold, supply temperature and cabin air temperature.

MOST pax seem to 'feel' the supply temp more than the cabin temp, largely because a lot of them do not bother to turn off the overhead louvres if they feel cold air, depsite the fact that the cabin itself may be hot. It is always a 'juggling act' to get it right.

A full cabin nearly always needs a significant cold flow, and it is complicated if the cabin gets hot on turn-round as the system will then go nuts trying to cool the cabin at first.

I'm sure the Ryanair crew were trying!

christep
21st May 2004, 14:26
As a pax I regularly have the opposite problem - cabins too hot, particularly on BA long haul. To me it is always better to err on the side of "too cold". It is much easier for a pax who feels cold to wrap up in a blanket than it is for one who feels too warm to do much about it (particularly now that a diminishing number of aircraft have individual air vents).

25F
21st May 2004, 14:42
Thanks for the replies, as always...

Just to clarify - I would have thought that at altitude the cabin would need heating, not cooling?

Globaliser
21st May 2004, 19:18
As I'd always understood it, the cabin air is bled from a point in the engine where it has already been significantly compressed by the compressor stages. Like a bicycle pump, this makes the air hot. That's why the aircraft has air conditioning packs to cool the air before it's fed into the cabin. The air conditioning, of course, requires energy to run, thus consuming fuel.

But it would be good if someone who actually knew what they were talking about came and posted the true answer.

TightSlot
22nd May 2004, 06:19
I'll try and drum up some technical support from a pilot or engineer for this thread - watch this space

Notso Fantastic
22nd May 2004, 09:45
There are many misconceptions still current about cabin heating and cooling and general airflow. Long ago, in the dim and distant past on the Classic 747, when pax loads were below a certain figure, it was normal practice to turn one of the three airconditioning & pressurisation packs off as the air demand was lower and they cost monsy to operate (drawing high pressure bleed air from the engines causing slight loss of efficiency). This has never been the practice on the 747-400, and I'm fairly certain nobody does this anymore.

As far as temperature control goes, don't even start enquiring about economy with hot/cold cabins. None of the crew are interested in whatever academic connection you think you may make. The crew actually want to be comfortable as well as they do vastly more hours in that aeroplane than you!

Many aeroplanes have command of cabin temperature on the flight deck. People set normal temperature positions and leave it for feedback from the cabin crew to adjust. Cabin temperature indicators are quite untrustworthy as they can get clogged up with fuzz- they rely on moving air for temperature measurement. Many aeroplanes have temperature controls in the cabin for cabin crew use. There is the rub. That cabin crew may have been working frantically in the galleys in front of hot ovens and getting hot meals out into trolleys. Not surprisingly, they feel hot. So they turn down the air temp! If they are not doing hot meals and are hanging around, if they feel cold, up it goes. Now this bit is controversial and only for MCPs like me. Like all women have trouble reversing and cannot work out which way to turn the wheel, have you observed women operating temperature controls on heating systems at home/office? They never tweak it- they tend to rotate almost fully up or down. My old fashioned view is to keep women away from temperature control systems!

alexban
22nd May 2004, 10:03
Globaliser:
Indeed the air conditioning system on a plane takes air from the compressor.The air is used for antiiceing systems in flight,for systems cooling,for pressurization (the cabin and all systems-for ex toilets,hydrulic sys,etc) and also for comfort in the cabin.The hot air is driven to packs (where some of it is cooled by use of heat exchangers,and air cycle machines-a compressor ,followed by a turbine which cools the air, then the cooled air is mixed with the hot air resulting the desired temperature) .
This packs are not mechanically conected with the engine.Of course they use some energy to run,usually electrical or blead air from engines.
A hotter seting of the cabin air will decrease the demand of cooled air,but with an insignificant value in flight.
The problem is like this:
If the plane is full,then we'll select a lower temp,to keep for ex 24 C in the cabin.If you have only half pax,then it's req a higher temp to keep the same 24 C .Normal.( on some planes all it's automatic,just select the desired temp)
The temp in the cockpit it's usually controlled by a diferent system then the cabin.Also,we have a lot of electronics that are also cooled,and they are also producing heat.So,my point is that a pilot will know the cabin temp only from the cabin temp indicator and also from the cabin crew.
The cabin temp sensor it's positioned somewhere in the cabin,not generally at an ideal position.On some of the planes I flew it's at a higher level,so at a higher temp,almost near the ceileing.
Also ,there are people that like 20C versus ones that like 28 C.
I usually try to keep the temp at about 24-26 C,but sometimes the temp indicator gives me a not so accurate value (for diff reasons,as I stated above)
You SHOULD tell the cabin crew to ask for or correct the temp in the cabin.Keep in mind though,that some of them may like a cooler temp (they are moving around,working),so ask another one if you feel uncomfortable.
I can assure you that we-the pilots- have no reason to keep a specific temp dictated by some fuel usage,economy bean counter,or whatever.
Brgds nice flights
Alex

flapsforty
22nd May 2004, 14:34
Ryan Airs fleet is mainly 737-800s. The temperature is notoriously difficult to get right on this type. Yes Notso, even for male pilots. :rolleyes:
On the 800 there is a 'cold-trap' at about row 14 for example; never mind what the pilots do with the temp controls in the cockpit, walking to the back during flight you can feel a wall of cold air at row 14.

It takes a lot of fine tuning of the buttons that control the temperature of the inflow-air, to get it comfortable for the pax. With the locked cockpit door, this usually takes 3 or 4 calls between cabin and cockpit for that purpose alone.
Which is fine when you have the time.....
But flying with the Minimum Required Flight Safety Crew like many 737 operators in Europe do these days, cabin crew is always short staffed for the amount of service they are expected to provide. Companies calculate down to the minute what they can get cabin crew to do. And on short stretches (80% of what the 737 does) time is a scarce commodity for the cabin crew.

But you're the paying customer, so if you're cold, tell the FAs. And if you're still cold after 10 minutes, tell them again.
Cold air lies low, at about the level you are sitting as a passenger. Hot air rises up; to about the level wheere out heads are while we are running around like demented wasps.
We won't feel the cold the same way you do, so you need to tell us when you're freezing.

I spend way too much time both as a freezing-passenger and as a sweating FA on the 737 so this is a subject close to my heart :)

AIRWAY
22nd May 2004, 14:51
I spend way too much time both as a freezing-passenger and as a sweating FA on the 737 so this is a subject close to my heart



Sweating :confused: High cabin temperature or low levels of work :E

:ok:

flapsforty
22nd May 2004, 15:24
Airway, your bags packed yet? :E

25F
22nd May 2004, 18:21
Fantastic response, thank you everybody. I'll be doing my best to avoid row 14 on Monday (STN-VCE) and Thursday (TSF-STN) evenings!

Incidentally I was reading today that the 7E7 will not be using bleed air for the cabin, but will take air from outside and use electrickery to condition it.

AIRWAY
22nd May 2004, 20:45
Airway, your bags packed yet?

Lady Flaps,

You trying to get rid of me :ooh:

By the way it's half way there, just need to buy a few more summer items, but dont worry, i'll try not to forget your "postcard". :E

:O

mini
23rd May 2004, 17:20
Slight divergence,

Apart from providing cool air, overhead vents also provide a means of deflecting BO on flights eminating from places where such odours are accepted as natural, discretly of course...

Airbus, in its wisdom has deleted these items from many of its craft, much to my chagrin.

Is this an emerging trend?

:sad:

PAXboy
24th May 2004, 19:20
Airbus, in its wisdom has deleted these items from many of its craft, From an outsiders point of view (or should that be insiders point of view, if I am inside the cabin?:= )The only reason that a manufacturer leaves features and equipment out is to save money.

They have probably stated that they can save weight and cost and that their air handling system is 100% flawless and the carriers have agreed with them. Cynical? Me?? :hmm:

--------------------
"I tell you, we are here on Earth to fart around, and don't let anybody tell you any different." Kurt Vonnegut, Jr.

takenthe5thamendment
24th May 2004, 22:16
One thing that has always concerned me is the 'quality' of the air we PAX (and FA's) have to breathe and the 'sharing' of airborne bacteria.
Surely by increasing the temperature it provides an excellent breeding medium for bacteria - that's why we sometimes suffer colds after a flight.

I have just done a search and come up withTHIS (http://www.flyana.com/air.html)

See the section on SARS and TB.

Scary Stuff!

High Speed Descent
25th May 2004, 00:18
Hi Christep & 25F,

To add on from what's been said above;

The 747-400's have a system known as A.C.C.M. This automatically regulates the temp at 24C after an hour of manual intervention.

Scenario:- Flight deck set the temp on the dial at the one O'clock position (22C-23C) during preflight (assuming that is as comfortable as they felt when they walked up to the flight deck!).

If the purser now feels that say the Economy section is too hot he/she can adjust the temp accordingly at a panel near her/him.
About an hour in cruise the ACCM kicks in and re-adjusts the temp to 24C and stays there until re-adjusted then an hour later kicks in again...........and so on..

In my company when the load is high and esp during meal service, crew are encouraged to turn on a Higher Flow of air for a period at the descretion of the Crew. This however increases fuel consumption.

During climb and descent the rate of airflow as defaulted to high.

Hope this helps Cheers.

TightSlot
25th May 2004, 00:18
takenthe5thamendment
With regard to air quality, I took this up with our Safety Team some time ago, following questions from customers, and was advised quite specifically that the air filters that we use in the cabin are equivalent/identical to those use in hospital operating theatres. As such, they provide a higher level of protection to customers than is available on say a bus, train or in almost any air conditioned public environment. SARS and TB are alive and well in some major cities, and there is no greater risk from being in an aircraft than from being in proximity to infected persons in these other locations, in fact, possibly less.

Aircraft cabins are commonly pressurised to some 6-8K feet, depending upon the actual cruising altitude. This, naturally, results in lower concentrations of oxygen than at ground level. This should not be confused with a deliberate attempt to induce hypoxia as a cost saving exercise. Diana Fairechild's symptom list includes:

. You are having difficulty concentrating on tasks such as reading or business work.

. Your lungs ache.

. Your skin feels clammy.

. You feel nauseated (and there's no turbulence).

. You have a headache.

Any or all of these symptoms are vague and subjective in the extreme, especially on a night sector, and it is entirely possible that they are unrelated to the Cabin Air supply. Her suggestion that customers should require the crew to make aircraft system changes based on these symptoms are unwise. Her other suggestion that customers should demand the use of an oxygen bottle is both selfish and misguided. The oxygen bottles provided on an aircraft are primarily intended for use either after a decompression or for passengers experiencing severe medical conditions. The use of oxygen to overcome a headache or an inability "concentrating on tasks such as reading or business work" might later deprive someone else in greater need.

Higher up this thread there are some explanation from pilots and Cabin Crew as to how the various systems work and are applied. Against that, we have Diana Fairechild, a lady who clearly has a vested interest in writing about a more sensationalist version of events. In her case, a little knowledge has clearly proved to be a dangerous thing.

I can only pass on something I've found to be the case in 24 years of flying - Not once have I met a pilot who admitted to switching off packs to save fuel, or to even feeling pressured to do so. In my experience of pilots, any corporate request to do so might well result in the opposite action. Neither pilots, nor cabin crew have any greater wish to work in an unhealthy environment than anybody else. Diana fairechild's suggestion that they would do so is crass.

takenthe5thamendment
25th May 2004, 02:52
TightSlot,

A very interesting, and reassuring response from you.

Thanks! :ok:

christep
25th May 2004, 04:46
HSD,

Thanks for that. Am I alone in thinking that 24 degrees is FAR too hot for a default cabin temperature, particularly on overnight flights? Do people normally keep their bedrooms at that? Personally I would prefer somewhere around 18 degrees - as I said, it's far easier for someone who's cold to get a blanket than it is for someone who's too hot to start stripping off.

GlueBall
26th May 2004, 20:48
"...Not once have I met a pilot who admitted to switching off packs to save fuel, or to even feeling pressured to do so...."

If you switch all the packs off you'd be blue in the face, as packs are not just for conditioned air, but primarily for pressurization.

:ooh:

moo
26th May 2004, 22:42
I believe the BA 747-400 target is 19 degrees celcius in all zones (or at least that's what EICAS says!) :ok:

TightSlot
27th May 2004, 03:05
Thanks GlueBall - point taken and grammar will be tightened :O

BahrainLad
27th May 2004, 08:19
I remember when BA first introduced "Sleeper Service" in First around 1993 they issued all passengers in the cabin with a luxurious filled duvet.

Thick duvet = hot and sweaty passengers. So the cabin temp was turned down.

Which meant that the punters in Club were shivering under their polyester blankets!

Teddy Robinson
28th May 2004, 16:08
....... Takenthe5th touched on a good point.

As the bleed air is taken, cooled, then fed to the aircon packs, a small but significant fuel saving is to be had by recirculating the cabin air.. ergo less bleed air required for a given cabin temperature, better fuel economy = happy accountants.

Its bad enough for a passenger knowing that you may well be breathing in the latest flu variants donated by a dozen transit pax from Hong Kong..

For the folks who fly up to 6 sectors a day looking after your comfort and safety, it becomes a real health issue, my take on using recirc is that it is very useful for keeping the (empty) aircraft cool on a long turnaround at a hot airport, or likewise warm during the winter months, pax on board = fresh air.


:cool:

flyblue
31st May 2004, 08:33
I am currently working on 737 and the A320 family. It is true that on the 737 (Flaps knows how much I love that plane :rolleyes: ) there is a temperature problem, especially at doors/ emergency issues level (the galleys are flying igloos:*) .
On the A320 family we never have that kind of problem, even if the Captain or FO (or both) is a woman :rolleyes:
The best solution however is on planes with cabin-controlled temperature. Less waste of time requesting adjustments and what's more, when you ask the F/D you never know the increase/decrease you are going to get, while, being on the cabin already, you are the best judge to decide the degree of change it needs. On those planes the minimum temperature is usually (on my experience) set around 18, with a 7-8 degrees range. Usually you get the less complaints at 24, with 20 being far too cold even for crew who are moving around.