Temperature on night flights
 

Can anyone tell me why it is so difficult maintaining comfortable cabin temperatures on night flights?
I have just returned on a long-haul flight in Business Class and we were all cooking!! I have heard that the cabin crew turn the temp up because they think that will make people sleep. Does anyone know if there is any truth in this? If so, why can't they realise that it has the opposite effect? They DO seem to be able to control this because when I was wandering around, another passenger said that he couldn't sleep because he was too hot and I agreed. A member of cc overheard and said that he would turn the temp down which he duly did and we all seemed to get to sleep!!
Yet I have had the opposite problem in Economy where the blankets are thinner and it often seems to be too cold.
Can't airlines maintain optimum temperatures on-board?

Yes, but optimum for who?

Airliners have different zonal heating systems. This means that the whole cabin is often divided into two, three or four separate zones for automatic heating purposes. Given that any one zone may contain over a hundred passengers, it is impossible to find a temperature that will satisy or be optimum for everybody.

Where individual overhead blower vents are installed, the passenger has some small control over their own environment to the extent that they can cool themselves in a warm cabin, but these are by no means universal and even where fitted they don't suit everyone.

Automatic heating controls don't differentiate between night and day, they simply regulate to a set temperature at the location of the thermostats, much as the heating in your home does. People who are tired, or at the low point of their circadium rythmn will usually feel colder even though the ambient air temperature hasn't changed. On a night flight this often results in an increase in the number of people seeking an increase in temperature. Of course not everybody is affected by this and some will also find the increase uncomfortable.

Often (but not always) the temperature is controlled from the flight deck, and there can be few pilots who aren't just as frustrated at constant requests for temperature adjustments, often in reversal to a request made just a few minutes earlier that wouldn't have had time to take effect.

So to answer your question, the airlines usually do maintain an optimum temperature on board. It is normally around 24c. It is requests from passengers and crewmembers that results in alterations to this. With hundreds of individual comfort criteria to consider, and only two or three automatic thermostat zones, you begin to see the difficulty. Nevertheless we still try, and await advances in technology.

I fully understand the problems involved in satisfying 250+ pax, but I would have thought 24C is on the high side to begin with. Would 20-21C not seem more appropriate perhaps?

Just me maybe but I prefer the cabin to be cooler not warmer - lets say 22oC / 23oC. I can cover up, grab a blanket if chilly but for the sake of others in the cabin I don't think getting naked is the solution to feeling too hot and stuffy.
However I sympathize; many Asian mates who have been used to hot and humid temperatures since the day they were born and who have BMI figures that near zero freeze up & hibernate if the temperature goes below 25.

I, too, am one of those that believe in cool temps rather than hot (my car ac is set to 18 degrees, and I sleep with windows open even when it is subzero outside)

As wassaid above, if you are cold you can always add a layer to be warmer, but if you are too hot there is nothing you can do.

My belief is that the cabin crew set the zonal temperatures based on their own comfort levels - bear in mind they are normally seated next to the doors, which will be cooler than elsewhere.

Therein lies the problem.

On the two Boeing types I fly, there are either 3 temperature zones (including the flight deck) or four. The temperature selection range is from 18c to 30c marked in 2 degree increments, although it can be set to any temperature in that range. Obviously the mid-point temperature is 24c.

The actual temperature set will depend on many variables. If the aircraft has been sitting for some time in very warm or very cold ambient conditions then the cabin will be often be set at one or other extremes in order to achieve a rapid warm up or cool down as may be required. Much as you might do in your car in similar circumstances.

Similarly, if it is daytime in a warm country where people are used to air conditioned buildings and transport, then a cooler environment may be set to reflect the expectations. During the flight the temperature may well be raised to reflect the change from day to night, or peoples greater sensitivity to cooler temperatures as a result of inactivity.

Truth is, if you leave the temperature at a mean average, you can bet that someones request for an increase will becomes someone elses request for a decrease without any change occuring at all.

With three temperature zone controllers, you can guarantee three people being happy. The rest will either be happy or unhappy to varying degrees depending on their own circumstances. Perhaps we should fit those placebo type thermostats you often find in hotel rooms, where you can move the dial to convince yourself that something is happening, but nothing actually is.

Even if you could get the temperature just right for the majority, there will be variations where it is warmer near the inlet ducting. Cooler near the windows, unless the sun is streaming in. Cooler near the door frames. Warmer near the galleys.

Best to take a personal mini fan and a blanket and modify your own micro climate.

Cabin crew usually don't set them (although they may on certain aircraft types, and I wish they did!) In fact the cabin crew are only seated near the doors for a short period during take off and landing. Normally they are very active and working in galleys. Generally they request cooler temperatures for these reasons.

I think there's an element of exaggeration in some of the reports. I routinely monitor the cabin temperature and the only time it ever goes above 25C is at the start of the flight when the aircraft has been baking on the ground. In flight a typical temperature is around 22C. If I see it anywhere above 24C I'll turn the master control down to reduce it to a sensible temperature. The temperature in the cabin is routinely managed by flight crew in this manner.

By that comment, it would appear that you are a shorthaul person.

What we are talking about here is long overnight flights, by definition longhaul flights.

On these flights the cabin crew spend a lot of their time inactive by doors while the passengers attempt to sleep, after the service is complete.

The flight crew set basic temperatures which are then varied by cabin zone by the cabin crew. In my extensive longhaul experience, they usually complain during the service that the temp is too high (often as a result of inadequate cooling capability on the ground) and then after the service ramp the temps back up from the achieved 21-22deg to 25deg after the service when they themselves are inactive.

The sectors I fly vary in length from 2 hours to 13 hours. Day and night. I think I have a reasonable idea from 28 years of doing it, how to define it.

As I stated earlier, there will be differences on aircraft types, but the two I currently operate only permit temperature control from the flight deck. So any request for variations must come from the cabin crew.

In my experience, if the cabin is either too warm or too cold, it is unlikely to result in the crew achieving much rest (wherever they may be sat) due to call bells going off or frequent passenger visits to the proximate galleys.

Your doctor should frown at this, mine did when I said something similar. It is, I was told, very unhealthy to breath very cold, sub zero air into ones lungs, can lead to serious problems later.

I found that the CC set the temp according to what they thought was normal, as they were all delightful young ladies from Singapore anything under about 28C was considered 'too cold'!

At home, I prefer a warm bedroom, the window slightly ajar. When on long haul - I accept whatever the cabin is set to. If it's cooler than I like, I get an extra blanket. I have never asked CC about cabin temp but then, I've only been a long haul pax since I was nine and I'm now in my 50s.

I have to concur with you, except my experience was actually in Economy on a BA flight back from Boston. The temperature was far too hot, so much so that my wife said she'd never fly BA again. However, I'm assuming from all the comments that this situation isn't just limited to BA.

moleytt

I think there have been some studies on this. This isn't one of them but an interesting article nonetheless...

Best Temperature For Sleep, Effects of Temperature on Sleep

Perhaps it's where you are sat in the cabin. In Economy on 20 trips to Australia I've always travelled shirt sleve order. (short sleeves) I've often been too hot when when others, usually in the centre isles, are wrapped in blankets.

You can't please all the people all the time.

> You can't please all the people all the time.

I typically find flights warm and if there's no overhead vent to open - stuffy as well.

My wife sitting beside me will typically be wrapped up and wearing a pullover and complaining it's cold.

It's a no win.

My inclination would be to avoid choosing to travel with a carrier for more than a few hours if I knew they had no overhead vents.

A bit of info on a/c type...

On small turboprops, you opened the door on the ground= A/C
Passed out blankets to the pax= heating :p

737: Too cold, call flight deck. Too hot, call flight deck, fan self with safety card

767: Close/open vents as required, pass out blankets, call flight deck

A330: Crank the temperature up/down in a zone as much as we liked; it would only go 2'C above or below whatever the flight crew set it to. So even if it said 25'C, if the F/D set it at 21'C, it would only go as high as 23'C or as low as 19'C, no more than that.

So, if you had a captain who was a reptile (i.e. cold-blooded) then too bad for you, you all froze!!

Some Airbus have the heated floor panels adjacent to the doors, the temps of these could be controlled as well for those pax & crew sitting there. Depended on the operator though, as to whether they installed and/or used them

Thank you all very much for your responses. Very enlightening. And not really any support for the theory that cabin crew believe that the higher temperatures make people sleepy!! Or that they have much control!! Shame - as that might be easier to rectify if we can just get the message across that most people find it too hot and will sleep better (and thus stay out of the galley and therefore out of their way!!) if it's cooler. But it does seem like it's horses for courses and if they turn it down, they will have complaints from those who are cold!! So I guess I'll just have to strip off!! That should make them turn it down!!

Could I ask any engineers out there another question.

I like individual overhead air jets. The cabin can then be on the warm side, but if the jet is cool the desired temperature can be maintained by adjusting the strength of the air jet. Unfortunately many aircraft such as BA LH no longer have individual jets. Presumably the reason for this is economic - we all know about airlines cutting requesting pilots to turn off packs to save fuel.

My question is: how much fuel is actually saved by not having individual air jets. Studies must have been done. Is it significant?

Another, related, question comes to mind. The rear of a 747 is always stuffy on the ground, prior to start up, even with the APU on. If the APU is unservicable conditions are generally very uncomfortable even when it is not too warm outside. Presumably this is due to the limited capacity of the APU and the way that air is distributed along the cabin. I have found that when there is an a ground pre-conditioned air supply - almost universal in the USA, also at LHR T5 - conditions are much more comfortable. Presumably this supply is more powerful than that from the APU?

There is another variable which effects one's perception of temperature aboard. I continue to experiment however the basic conclusion is:

Drink full bottle of red (or equivalent) = It's too hot. Kick off duvet, blanket or whatever.

Drink no alcohol = It's too cold. Tuck duvet, blanket in tighter. Add sweater.

Somewhere in between there is the right balance for each individual; but each individual will of course be different...

Part of the decision to not fit individual air vents will be the fit-out cost to the company that specifies it. This is capital saving, but operational savings will also follow.

In some cabins, the jet is very far above your head and you have to have it turned up really high to 'reach' you. So that is another reason for not having it - because it just doesn't do the job.

I must state a preference FOR individual vents.