I normally enjoy air travel.
There are only a few things about it that I don't care for.
And if you manage to forget about having to spend hours stuffed into a cramped seat with
some kid kicking your seat back, my only remaining issue is how low the temperatures in the passenger
cabin usually are!
So, is there an aeronautical reason for this suffering?
At first, I thought that by setting such freezing temperatures inside the plane, airline companies
were just trying to help passengers acclimate to different weather conditions.
After all, the weather might be way colder in the place they're heading to.
Well, I was wrong.
Despite how ridiculous it may sound, chilly winds are blowing through the passenger cabin
to provide you with maximum comfort!
Wait, what?
First, the temperature in the cabin isn't as cold as it may seem.
It's normally kept between 71 and 75 degrees, and rarely drops lower than 64 degrees.
In fact, that’s the average temperature in most office buildings; so what's the problem?
Don't forget that while traveling by plane, you don't get up from your seat and move around
very often.
As a result, your body doesn't produce enough heat to warm itself, and you feel colder than
you would under different circumstances.
On the other hand, if the cabin is fully occupied, the passengers themselves give off enough
heat to significantly warm the cabin.
Anyway, it turns out that there’s a connection between the pressure and temperature in the
passenger cabin, and people fainting mid-flight!
First and foremost, passengers tend to lose consciousness in the air more easily than
on the ground, due to a special condition called hypoxia.
It occurs when the body tissues (including the brain) don't get enough oxygen and can't
work properly.
But if the temperature on board the plane is too warm, and the pressure is higher than
normal, these factors can worsen and increase the probability of a negative reaction.
Of course, in different people, body temperatures vary, and the temperature that’s comfortable
for one person may seem too hot or too cold for another.
But just to be on the safe side, airline carriers prefer to keep temperatures in the passenger
cabin a bit lower than normal.
And if you put it this way, I'd rather wear several additional layers of clothing than
allow that poor guy next to me to black out.
However, you’re not as likely to be shivering throughout the flight if the plane you've
taken is new.
The thing is that newer aircraft have more advanced thermostats, which can regulate cabin
temperature more precisely.
And even though it's impossible to adjust the temperature around individual seats, flight
attendants can regulate it by zones.
By the way, cabin crew members will usually only raise the temperature after passengers
ask them to, because they don’t usually have an issue themselves with the chilly temps.
After all, flight attendants are constantly working and moving while the passengers stay
in a relaxed state, and that's why their perception of a comfortable temperature is very different
from yours.
And finally, have you noticed how hot it is on the plane before it takes off, especially
in contrast to the mid-flight chill?
The thing is that the air conditioning on the aircraft is always turned off to save
fuel until the plane leaves the ground.
As a result, the combined body heat of all the people onboard, plus the absence of the
air conditioning, can warm the cabin up to an uncomfortable temperature.
The maximum temperature on the plane shouldn't be more than 90 degrees, but luckily, you're
unlikely to experience such heat while flying.
Ok, now it's clear that the passenger cabin is so cool for your own comfort.
But what about its dryness?
Is this gripe unreasonable as well?
Nope, even pilots admit that the average passenger cabin is incredibly dry and, thus, dehydrating.
It has just 12% humidity, which is way drier than most deserts!
Unfortunately, airplane manufacturers can’t do much to solve this problem.
The dry air is a byproduct of flying at extremely high altitudes, where there’s almost no
moisture whatsoever.
Of course, humidifying equipment in the cabin could partially deal with this problem.
But that equipment is pretty expensive, and the results wouldn't be worth the money.
What's more, the increase in moisture levels on board could cause the guts of the airplane
to corrode.
By the way, what's the most comfortable temperature for you on board the plane, and how do you
deal with the chill in the passenger cabin?
Let me know down in the comments!
Anyway, now the temperature inside the plane makes sense to me.
But what about the cargo hold of the airplane where your dear pets travel?
What are the conditions in there?
Many people are surprised to know that the hold is pressurized, just like the passenger
cabin.
On top of that, to air-condition the cargo hold, they use the same air as in the cabin.
However, since this air is directed from somewhere else, it ends up a bit cooler when it reaches
the cargo hold, which is also less insulated than the passenger cabin.
That's why cargo hold temperatures, although varying depending on the plane type, normally
don't get higher than 45 degrees.
Isn't that too cold for the animals that are transported in the cargo hold?
No need to worry: the bulk area where they’re kept is heated up to 64 degrees.
And finally, if a plane is transporting goods that are sensitive to temperature, there are
special cargo bins with temperature controls inside.
But if the temperature inside the cargo hold isn't that freezing, and the air is pressurized,
why do stowaways rarely survive this experience?
The problem is that these people don’t hide in the cabin or hold, but in the wheel arches.
And those are fully exposed to the elements.
And as you know, the higher a plane climbs, the colder it gets.
If the temperature before take-off is about 70 degrees F, then at the altitude of 35,000-40,000
ft, which is the usual cruising altitude, it can drop to -70 degrees F!
Very few people are prepared enough to hold out in such low temperatures, even for an
hour.
By the way, do you know why airplanes leave white trails, also called contrails, in the
sky?
To tell you the truth, I've always thought it was some sort of emission, just like those
produced by old cars.
But it turns out the contrail appears for the same reason you can see your breath in
cold weather!
The exhaust from the plane is humid and hot, and when it mixes with the frigid air and
low pressure at cruising altitude, the water vapor not only condenses, but can also freeze.
This process looks exactly like streams of white smoke in the sky, just like your breath
on a cold day.
Contrails can vary in their thickness and duration, depending on the humidity and temperature
of the atmosphere, as well as the plane's altitude.
And that's convenient, because you can look at a plane’s contrail and predict the weather!
Keep in mind that if a white trail left after a plane is thin and short-lived, it means
that up there, the humidity is low.
Therefore, the weather is most likely going to be clear.
But once you see a thick and long-lasting contrail, prepare for a storm - such a trail
indicates high air humidity.
From time to time, you might notice previously straight and strong contrails become wavy,
or even leave bizarre rings floating in the sky.
It means that up there, a plane is either experiencing turbulence, or flying through
air with different density and temperature.
Another surprising phenomenon you've probably witnessed is two planes flying nearby, but
with one of them leaving behind a thick, long trail, and the other - an almost invisible
one.
The reason may lie in the fact that different planes have different engines.
For example, if a plane has a newer engine, its exhaust might have a lower temperature,
so the contrail will differ dramatically from the one left by a plane with an old engine.
Besides, the length and thickness of the trail depends on a plane's power settings and cruising
altitude.
In this latter case, you might think that the two planes are flying side by side, but
in fact, that's just a visual effect, and they’re in different layers of the atmosphere.
And since one layer can be way more humid than the other, the planes leave different
trails.
So I’m done now, and it’s time to hit the trail.
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