Why You Get Dehydrated When You Fly | Airline Pilot Explains

Why You Get Dehydrated When You Fly | Airline Pilot Explains

why do you get dehydrated during or
after a long flight because you were drunk well not exactly I’ll explain it all coming up hey 74 Crew welcome back if you don’t know me
my name is Kelsey I’m a 747 pilot my channel 74 gear is all about aviation
today I’m in Seattle Washington I’m at the hotel that’s really close to the
airport to take the dreamlifter out so the view is not so great and it’s rainy
and a little bit cold so that’s why I have my sweater on after a long flight
you could get very dehydrated be thirsty have a headache all symptoms of
dehydration in this video I’m going to explain why your body dehydrates more
during a flight let’s get into it I pulled a few numbers off the internet
just so you have things to compare with how dry an aircraft is versus normal sea
level at sea level the average humidity in the air is 40 to 50 percent where in
an aircraft it can be as low as 10% if your body isn’t used to that level of
humidity you can rapidly dehydrate and a lot of people believe that the reason
the humidity is so low is because it’s just recycled air but that’s not the
case there is some air that is recycled but
there is new air getting pumped into the aircraft all the time that’s how it’s
able to be pressurized I bet that really blows your mind if you watch the video
where I explained how a jet engine works on a commercial aircraft you may
remember this picture right here in this section the engine here the air is
actually getting compressed before it is combined with fuel and actually used to
thrust the aircraft forward now a portion of that compressed air before it
arrives to the gas section of the engine is used to pressurize your aircraft that
means that compressed air is actually getting pumped inside the aircraft and
that’s actually how we stay pressurized in flight for a long time however that
air that being sucked in from outside the aircraft at 30 or 35 or 40,000 feet
in the air is very very dry so that air that we’re continually using to
pressurize the aircraft with is getting pumped in from 30 to 40,000 feet that
very very dry air is partially to blame for your dehydration if you’ve ever been
to Las Vegas on a weekend or you’ve ever been out somewhere in the
desert for a couple of days you’ll realize just how fast your body
dehydrates compared to when you’re in your hometown and it’s not all because
of your partying and drinking don’t know me but if you’ve been to Vegas before it
I know I’ve been there a few times I actually did part of my flight school
there the average humidity there on average is
about 25 percent so at sea level 40 to 50 percent Vegas could be 25 percent on
average and then in a plane it could be as low as 10% so if you’ve been to Vegas
before you know how fast your body could dehydrate especially during the
summertime and you have to stay hydrated it’s the same thing that happens on an
aircraft because of my job and doing long flights all the time my body’s a
climatic to that type of dry air I think and I’m often drinking water all
throughout the day if you ever see me walking through your city a lot of times
you’ll see me with a bottle of water in my hand because my body is used to
having that continual hydration which makes it so when I’m in flight I’m not
dehydrated I personally hate having a headache especially when I’m flying so
it’s important that I hydrate all the time and that’s why you’ll always see me
drinking water and it’s not like you can just get on the plane and to start
pounding water because what’s going to happen is you’re just going to be
bothering everybody in your aisle and getting up all the time to go to the
bathroom I would recommend starting to drink water a day or two before your
flight to actually start hydrating your body and that will help you prevent
headaches and feeling tired at the end of the flight you’re wondering just how
often I’m drinking water once in a Hollywood vs. reality video I was doing
on flight I was drinking water in the middle as soon as Denzel was drinking
liquor for some reason I just started drinking water if you haven’t seen that
video I’ll put a link to it right here I look forward to hearing from you
until then keep the blue side up

100 thoughts on “Why You Get Dehydrated When You Fly | Airline Pilot Explains

  1. I am terrified of flying to the point where I actually start to cry, and I have zero interest in planes. For some reason I ended up on channel, and I think I have watched about every video you've uploaded 😂 It actually calms me. And also, I really like your personality, so I have subscribed 👌

  2. Even a rookie flight attendant should be able to field first time passenger topics like this. I'd hope that Captain Nodsmirk could cover more serious and complicated topics for people who want in-depth discussion instead of a series of low effort twitter memes.

  3. I normally drink 60 – 70 oz of water per day. Leaving for Europe next month on longer than usual flights for me. Do I need to up my current consumption or make sure it doesn’t drop below that. Flying business class so alcohol will surely be consumed!

  4. Because I refuse to drink liquids before and while on a flight so I don't have to use those eensy weensy bathrooms.

    Only half true.

  5. Best flight I ever had was from Hong Kong to London. They dipped the cabin temperature enough that you could actually sleep and not wake up feeling hungover. I can never understand why the cabin temperature is always so hot – that's the biggest problem I've always had. Most of my long haul flights have been horrible – literally can't get out the door fast enough.

  6. I lost my job 3 times in the last 18 months due to company bancruptcy and I really can't find any energy to go for another job. I'm a good pilot but I really suck at those selections especially in the interviews. I watch your channel since day 1 and I wish I had 1% of your confidence and enthusiasm. God bless you Sir

  7. Misleading video because
    1) humidity percentage is meaningless without knowing the temperature and pressure of the air (it's the percentage of the moisture carrying capacity of the air, which is lower in lower temperature or pressure).
    2) the body doesn't work like that, although getting on a plane already somewhat dehydrated won't help.

  8. But how do you keep the balance on the plane between drinking and need to urinate? I can imagine it's not convenient to head over to the bathroom multiple times with today's' security measures in effect. Likewise, I still remember how I didn't drink enough water when doing long 3-4 hours flights during flight training lol

  9. Well, I get dehydrated and tired afterwards when I fly little airplanes that are not pressurized. Is there a reason for that?

  10. I once used my airline miles to fly around the world over a 4 day period. I've never been so dehydrated in my life and it was miserable. The next time I fly long haul I'm definitely going to heed this advice of hydrating starting a couple of days before.

  11. A couple things: do commercial or cargo plane have counter measures or any other defense against missiles and have you ever done a video on flame-outs. I watched a video on a citation jet that lost both engines due to fuel contamination. Able to glide 16 miles to a safe landing. See Baron pilot.

  12. I suffer this a lot down here in south florida, and on my first long XC to naples I completely forgot water, absolute nightmare

  13. If all that new air is pumped in the plane from 40,000 feet isn't it low in oxygen?
    Is the O2 level monitored in the plane and supplemented by oxygen stored in tanks?

  14. I brought a hygrometer on a flight from Stockholm to Bangkok. It was very interesting to see the humidity on the plane decrease over time, and it took quite a few hours before we reached the low of approx 20% (hygrometer was cheap, so wouldn't trust it to be more exact than +-10%).

  15. I'm a long haul trucker and driving 11 hours with the AC keeping my windshield clear makes me so dry my hands crack and bleed, especially during winter. Even without the ac system running, just the air blowing will dry the air around me. I feel your dry, flaky pain!

  16. Thank you Kelsey for the insight especially when I'm going from my former job as an English professor to a Flight Attendant (training next month). I never thought about how my new office space (an airplane) would differ and impact my body so much from old office (university classroom). Great topic & love the knowledge!

  17. I'm from Louisiana. I'm used to heavy humidity.

    this tells me is if I take a flight (like the one I dream to take but can never afford)
    Is drink a lot of water.
    Which may be hard as I'm a big soda and juice drinker.

  18. Thanks for all the video's I enjoy them, I have a question about the differences in airlines and their pilot's. What's the advantage of flying a budget airlines as opposed to flying a more expensive airlines, and are the budget airlines pilots less qualified than a more expensive airlines?

  19. Is that the reason why evaporative coolers don’t work in Las Vegas because the humidity is not high enough

  20. Hey buddy I have a question for youwhy would they let a jetliner go through Iran air space when there was tension going on with the US.. knowing they might be shot down

  21. Im not afraid to be an airline passenger, I just dont like the idea of it. Ive been on 4 planes in my lifetime. A metal tube flying 6 miles in the sky, going 400mph. I have no control over any of it. But… I love planes, and I would have to seriously consider doing it again if I knew Captain Kelsey was my pilot.

  22. Can you give, as per Las Vegas, an average humidity level in a commercial airliner?
    Also, what it might be dependant on?

  23. Hi, Kelsey! I have a couple of questions for you – is there any way at all that the people who build the planes could create a way to humidify the cabin air to make it more breathable or is that just something that's impossible to accomplish at those heights? If so, why? Thanks a lot, and hope you had a great Christmas and New Year's!

  24. Hey Kels, semi-related question. What would happen with a dual engine flame out or fuel exhaustion at say, Flight level 410? (Air Canada 143 for example). How would the cockpit and cabin stay pressurized? Could the APU run without much fuel? Does it have an auxiliary tank of it's own fuel? Or would the masks drop and you would have to get to FL150 or lower in a big hurry to avoid a slow loss of cabin pressure? In the case of the Gimli Glider they had a long distance to cover so losing altitude quickly was not favorable. How does a plane maintain pressure without engines? APU? Or would it be inevitable?

  25. I recently flew in a crj on a 2 hour flight just after a front had passed North Texas. The cabin was so dry my tongue started sticking to my mouth and my eyes dried out almost hurt to blink. I'm not used to anything below gulf coast humidity.

  26. 74 Gear should collaborate with Modest Pelican Gaming, and dedicate an entire episode to the importance of staying hydrated 🙂

  27. Never happens.
    Start with a six pack in the airport before flight purchased at the tax free.
    On board eat what they serve with a water or soft drink.
    After food, continue with beer.

    Never dehydrated however important to have isle seat near a toilet.

  28. Hi Kelsey so often you hear travel agents say dont drink the tap water from the plane. You are safer to drink the water from bottles. Is this fact or an old wise tail. Dont forget rota wing flying vs fixed wing flying cheers Tim

  29. Random questions..: Do pilots keep track of random personal things like fastest flight speed, time between airports, highest altitude reached, ect? Or do things like that not matter because of the strict scheduling / rules in aviation? Btw, I am a little surprised they dont try to add a little more humidity to the cabins to avoid dehydration. Although I am sure part of that is to keep corrosion to a minimal.

  30. Hey bud can you try the app Aerofly 20 on iOS and make a video ? I would love to see what are your thoughts on the 747 cockpit there which is all functional!! Thanks for the great videos.. super informative and fun to watch !

  31. Naw I’m sure the dehydration and faintness I felt coming back from Jamaica had more to do with the 3 rum punches I downed before getting on the plane and a little less to do with the pressurization lol

  32. I run my AC all the time at home (i love the cold) so im pretty used to drier than normal environments. But i honestly dont mind the plane being that dry. i would MUCH MUCH rather it be dry than a warm humid disgusting mess. Would have issues of mold growing in planes too if it wasn't that dry.

  33. Hey man found your channel last week great uploads your a cool dude wish you every success for the future

  34. Hi Kelsey a random question for you airline pilot such as yourself get into say an F-35 or any other military jet and flight it not talking about firing missiles or dog fighting just take off fly about and land yes or no by the way not really bothered about airliners etc but like your channel and watch every time you post something cheers bye

  35. I work a quarter-mile behind SeaTac Airport. Any idea why delta airline pilots come in so low to the ground? I never see any other airline do this its always delta.

  36. It's not exactly that the air outside is dry. The air outside the plane is 40°C or less at high altitude. The actual % humidity might be quite high outside, even to the dew point (clouds forming – essentially 100%) However, when heated to body temperature, the % humidity is quite low. Your lungs operate on 100% humidity. There are pulmonary surfactants which promote good gas exchange to blood and prevent the tiny alveoli from collapsing due to water cohesion. The the low surface tension makes for instant evaporation until the inhalation can take no more water. That's why breathing in -40°C is almost painful; you can feel the evaporation in your mucus membranes; and if you breathe too fast, the cold burns. It's also why your nose runs when it's cold. Your body knows to react with high moisture production when it's cold.

    Recirculation of passenger exhalation is a way to increase the relative humidity inside the plane and ease your dehydration — airborne illness propagates easily in this environment, so people complaining about getting sick every time they fly is real. The "recycled air" crowd is diametrically wrong.

    Maybe Kelsey can tell us if ozone or UV air purifiers are in airplanes, today. I think that was one thing tried to lessen illness from airplane trips while allowing more recirculation to ease dehydration symptoms. Another method is to bring in a lot more air from outside and try to exhaust the contaminated air before too many passengers rebreathe it. Thus, if you find it's dry as a popcorn fart, your operator is just trying to keep you from airborne illness.

  37. Have you been to the navigator hotel in Everett? Not fancy, but it has a 727 wing and a Fokker f28 fuselage Over the lobby entrance. 😺

  38. Regarding the Dreamlifter. How do you find it to fly? It is an interesting beast and not quite ungainly looking as the various guppy incarnations most similar being the CL44-O swing tail guppy. All this and you can can claim you’ve flown part of a 747-SP as well. 😺

  39. I have read that the water fountain or dispenser that is accesssible by passengers is very often contaminated with norovirus, like the drinking water aboard a cruise ship, and not sanitized as often as it should be. So I hope the drinks trolley includes bottled water, or I'll have to buy bottled water in the departure area.

  40. Kelsey, I liked your video but you did not present the full explanation to the reason why people traveling in an aircraft become dehydrated. This topic is drilled into us flight medics in class and on our board exams.

    Pressurized aircraft while at cruise have a cabin pressure presenting with the relative altitude of 6,000-8,000 feet (we will assume 8,000 feet for the comment), which presents the occupants with an oxygen partial pressure of 77kPa compared to sea level which is 101 kPa. This means that while the atmospheric oxygen is still 21% of the total composition, the available volume of oxygen molecules to breath is only 76% of the oxygen available at sea level (Boyle's gas law). Also, the decreased pressure decreased the atmosphere's ability to retain water vapor.

    With the decreased oxygen availability, occupants within the aircraft must breath at an increased rate (mild hyperventilation) to maintain proper oxygenation.
    With every breath occupants in the aircraft expel water vapor, which during normal breathing at a lower altitude breath at 12-18 breaths per minute which causes a person to lose 7 milliliters of water per hour on average. By having the decreased oxygen partial pressure the occupants are forced to breath with an increased rate (greater than 20- 25 breaths per minute) to make up the oxygen difference, which results in an increased water vapor loss, resulting in headaches, dehydration, and crappy feeling after prolonged flights. These same complaints are also the beginning signs and symptoms found with the beginning stages of altitude illness seen in mountain climbing.

    Thank you for taking the time to read my comment, I really enjoy your channel.

  41. Hi, Kelsey! What can you say about the radiation during the flights? I know one pilot, and he told me, that after 2 flights (both last for 1.5 houses) his skin tanned really badly. Does your eyes get affected, and are there any chances of getting ill?

  42. I wonder why aircraft manufacturers didn't install any air hydration device on boards of their planes?

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