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While I understand that at very high altitudes the ambient air temperature is extremely cold outside the aircraft (-56 F), it always bothers me that I find myself sneezing and genuinely uncomfortable once I'm about 30 minutes into my flight.

The question I am specifically asking is, why is the chosen temperature inside the cabin low as opposed to high? Surely it could be set a few degrees higher to a "warmer" temperature?

Kxy
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  • Have you looked for any information on this subject? A quick search turns up lots of reading material. Perhaps you could make your question more specifically applicable to available information. – Peter Schilling Jul 16 '17 at 02:19
  • Thanks for the link, very Interesting... I was not actually aware the cabin crew could adjust the temperature of the cabin, almost every flight I've ever been on (in the 10's) has been extremely cold, and they have all been on different airlines. I assumed this was due to way the air-con worked on airliners – Kxy Jul 16 '17 at 02:44
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    Typically the cabin temperature can be changed and is at the discretion of the Purser (Chief Flight Attendant). Also, generally speaking it's easier for those who are cold to get warm using blankets, but there is no such remedy for those who are hot. Do you really want the cabin temp turned up so that fat old men who heat up with all their personal insulation start taking their shirts off. Aslo, while the passengers may be sitting down, the flight attendants are working their asses off, and for male flight attendants carriers often have a rule that they must wear t-shirts. Foolish rule IMHO. – Terry Jul 16 '17 at 03:26
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    I actually prefer it cooler, as I get very sweaty as it is on long flights. I think airlines can cater to all preferences best by keeping it cooler -- if you are cold you can put something on; the reverse doesn't work. – Thomas Jul 16 '17 at 03:33
  • @Terry Sorry for misunderstanding but what is it you find foolish about the male attendants having to wear t-shirts? – Kxy Jul 16 '17 at 03:37
  • @Ksery Just my opinion, but the airline I retired out of had that rule, which meant male flight attendants were dressed unnecessarily warm in the hot, humid summers of the east coast, in the heat of the middle east and the heat of Africa, India, Indonesia, etc. We were a "low cost" carrier, so it was not like we were carrying upscale pax. And certainly the old men who would take off their shirts for their prayers on the Tel Aviv flights certainly didn't care. The unfairness, again IMHO, was that the airline didn't enforce that rule for pilots, and few of us wore t-shirts in the heat. – Terry Jul 16 '17 at 04:51
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    @Terry I believe he means undershirts that are half sleeve, thus adding an extra layer of clothing to exacerbate the heat. They are often worn in hot environments to stave off sweating (and sweat marks). – Burhan Khalid Jul 16 '17 at 05:25
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    Voting to close as opinion based, since in many hundreds of flights, I've never been too cold. – Simon Jul 16 '17 at 08:46
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    @Simon I think the question is valid. I've always remember flights as being cold since childhood. I always wish they'd just turn up the temperature 1~2 C. – kevin Jul 16 '17 at 09:45
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    @kevin But then I would be too warm. You say "too cold", I say "too warm". There is no "correct" temperature, therefore, it can only be opinion. – Simon Jul 16 '17 at 10:55
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    To prevent closure or reopen, you may change your question into How is the temperature selected in the cabin? and whether there are different policies among airlines (if not already answered elsewhere). Just for information, on most airliners air doesn't come directly from the outdoor, but is tapped at some stage of the engines, where it is compressed and very hot. It is then cooled and the temperature is adjusted by mixing with hot air, again from the engines, and air from the cabin. So in the end it is more costly (more fuel) to produce cold air than warm air. – mins Jul 16 '17 at 11:37
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    I think this question would be a better fit for travel.se. It's about CAT from the point of view of a passenger, and it's entirely a matter of policy, nothing to do with the flying itself. – Dan Hulme Jul 16 '17 at 11:51
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    I'm voting to close this question as off-topic because it is about commercial air transport from a passenger point-of-view. – Dan Hulme Jul 16 '17 at 11:52

2 Answers2

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On the 737, I can make the cabin as hot as I want to; the challenge is more often adequate cooling if the aircraft got hot on the ground. With the insulation that the aircraft has, the generated heat of 100+ people in a confined space overwhelms the cooling of the outside air. (Yeah, it's utterly counter-intuitive, and I can't explain the why, but that is the way it goes. With the loss of all bleed air, the cabin will get hot -- although that's at 10,000', where you descended after the depressurization.)

I've never been told to run the temperature hot or cold as a fuel-saving measure. In theory, you save a little gas by not running the AC packs in "High", but again, that's mostly used to get more cooling air. Or to quickly warm a jet that sat unheated all night in freezing temperatures.

If the cabin was unbearably cold on a particular flight, somebody just wasn't attentive to the temperature. On any modern airliner, we have the tools to warm things up. Maybe the flight attendants prefered a cold cabin & had sweaters to wear; maybe "really cold" to the OP is actually pretty comfortable to others; maybe the thermostat was indicating erroneously high temperature in the cabin so the automatic system kept putting out cold air; or, maybe the pilots were being jerks and "freezing out" the flight attendants (and passengers) for some reason. Unlikely, that last, but not impossible or unheard of.

As far as a preference to run slightly warm or cool, cool will generally win, simply because warm tends to make airsickness worse, while cool has the opposite effect. On a bumpy flight, the last thing you want is a warm cabin; the saying goes that "popsicles don't puke," and it is accurate.

Ralph J
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I feel with you. I have the same problem and actually take ski underwear with me for intercontinental flights. Makes you look foolish when standing in line at some terminal in tropical latitudes …

Cabin air is bled off the engine's compressor and first ducted through a heat exchanger to cool it down. It then is mixed with hot bleed air to adjust its temperature and humidified as desired. Then it enters the cabin through grilles in the ceiling and removed by further grilles near the floor.

As you can imagine, the engine loses some thrust when it is robbed of the air it would normally use to propel the aircraft forward. Therefore, in order to save fuel, cheap (= all) airlines try to reduce bleed as much as they can. In consequence, the heat entering the cabin by means of fresh bleed air is limited, while the outside air cools the whole cabin down continuously. After all, you sit in a tin can, the outside of which is flushed with super cold air at Mach 0.8!

Peter Kämpf
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