When is an airplane pressurized

This story was made in partnership with Republic Airways. Check out the full series here. Ready to apply for a pilot slot? Submit your application here. Live from the Flight Deck. John Pozadzides. Bryan Burke. Ken Mist. Sign Up. Swayne Martin Swayne is an editor at Boldmethod, certified flight instructor, and an Embraer First Officer for a regional airline.

Recommended Stories. Would You Go? How DME Works. Fewer thunderstorms and less turbulence mean more days in the air for you. Here are the advantages of fall weather flying in a GA aircraft. Latest Stories Load More.

Improve your pilot skills. Get Boldmethod flying tips and videos direct to your inbox. Our mission has never been more vital than it is in this moment: to empower through understanding. Financial contributions from our readers are a critical part of supporting our resource-intensive work and help us keep our journalism free for all. Please consider making a contribution to Vox today to help us keep our work free for all.

Cookie banner We use cookies and other tracking technologies to improve your browsing experience on our site, show personalized content and targeted ads, analyze site traffic, and understand where our audiences come from. By choosing I Accept , you consent to our use of cookies and other tracking technologies.

Reddit Pocket Flipboard Email. A Jet Airways cabin crew forgot to pressurize the cabin, resulting in passenger nosebleeds and ear pain.

Getty Images The never-ending nightmare that is commercial flying just added a rather horrifying new potential mishap to its roster. How airplanes are pressurized All airplane cabins are pressurized to simulate the amount of pressure felt at 8, feet.

So what happens to your body when an airplane cabin is not pressurized? Next Up In The Goods. Delivered Fridays. Thanks for signing up! Check your inbox for a welcome email. Email required. By signing up, you agree to our Privacy Notice and European users agree to the data transfer policy. Because of the way the system is designed, it is very difficult for the air supply to become compromised.

Great article, Ken. On a recent flight to TPA on an older , ears were popping as usual on the way up and down. Return trip on a , the pressurization was so smooth the thing I noticed was the very little bit of ear popping I had. However, the pressurization system on the newer is an improved digital system that includes features designed to increase comfort.

The pressure changes, while still there, should be a little smoother and less noticeable, making the flight a little easier on your ears.

As you noticed, passengers like it. Very informative, thanks. Do you have any insight about how flying affects the brain and blood vessels and if there are any dangers? Hi Ken, Many thanks for your explanation because I recently traveled on an Australian domestic flight on which I experienced pain in one ear, and I was wondering how and at what level the pressure was maintained.

I also noticed that perfumes seemed to suddenly be detected in the cabin air. Can and do pilots inject perfumes or other chemicals into the cabin air stream? Thanks again. Aircraft pressurization systems generally maintain the cabin pressure altitude at about feet or about No aircraft that I am familiar with has that capability. Most likely, another passenger was putting on, or spraying perfume. You might also have been smelling a deodorizer in a lavatory which is far better than smelling the lavatory!

In this situation, the flight crew will begin an emergency descent. At lower altitudes there will be sufficient atmospheric pressure for normal breathing. Thanks Ken for your reply.. I mean fuselage is air tight right? Then how its done…? It surprises many people that an aircraft fuselage is not airtight.

Even with the outflow valve fully closed, air still leaks out of it. Window and door seals also leak a little bit of air. So, if the pressurized air source is interrupted, the fuselage will slowly lose pressure. This is why flight crews will immediately begin descending the aircraft if there is a serious pressurization problem. Pressurization systems on every aircraft are a little different. The valves are usually operated by an electric motor that receives a signal from the controller. So a balloon inflated with air will weigh the same on a scale as an unfilled balloon.

An easy way to think about this is to consider a helium-filled balloon on the surface of the earth. Helium balloons float because they displace more air-mass than the mass of the helium inside of them.

After an aircraft takes off, the pressure inside the cabin decreases at a slower rate than the pressure outside the aircraft as it climbs. Your posts are great and interesting for me and I always read it… I am Iranian and I translate your post to Persian for my channel in telegram…I learn so much information from your posts and thank you for writing these posts. I occasionally fly over southern Iran when flying from Dubai to Germany.

You have a beautiful country. Hello Ken, I have a billion questions coming more as a result of curiosity than anything else. Recently we had a little baby and wife and I were trying to fly but the airline told us baby needed to be at least a month old to fly but Google said otherwise, what is your proffessionl opinion on flying a week old baby?

Please ask your pediatrician. Hello Ken, Great stuff on pressurizing the cabin. Quick question. My guess this is where the compression of outside air to be vented through the cabin plays a role??? This percentage is roughly the same at all altitudes that an aircraft operates. At sea level, air molecules including oxygen molecules are close together. WOW Ken, the answer to the question I could not answer. So simple the way you described it.

Thank you again. Your answers are perfect: Ask your Doctor, ask the manufacturer, etc. Just to let you know you are very much appreciated.

Hi Herbert, I think most of them are honest questions. Sometimes they forget that a doctor, pharmacist, etc are great resources. Hi Ken, Thanks for a really informative article that answered all the questions that went through my mind on a flight from Singapore to Perth yesterday. My question is does using bleed off air increase fuel consumption? I was on a Royal Jordanian Tri-star some years ago and several passengers fainted including me and we were told that the pilots would turn down the air-con to save fuel.

Does that make sense? Does bleed air increase fuel consumption? The less bleed air we steal, the lower our fuel burn is. The amount of fuel is relatively small on any flight, but it all adds up at the end of the year.

A typical component of the air conditioning system is the recirculation or recirc fan. The fan takes air, usually from a lower compartment, and pumps it back into the air conditioning ducts.

The fans increase overall cabin air circulation while lowering the airflow required from the pressurization system. Even the most efficient aircraft pressurization system has more air turn-over than your home or office. Your last comment has me stumped. If the cabin pressure is reduced to a dangerous level, the oxygen masks will drop down. I have no idea what could have been going on in your Tri-Star one of my favorite classic jets! Hi Ken.

I came across your article while trying to research whether or not I can ship an exterior steel patio door by way of airfreight on a major passenger airline without any Argon gas escaping. I was told by the airline, after they checked with their Dangerous Goods DG Manager, that it was okay because it was not compressed. I am still concerned that the gas may escape under pressure in the cargo area and the door would be rendered useless once it gets to its destination, because once the gas escapes, fog, or steam, builds up between the glass and appears cloudy.

My concern arose when the shipping worker told this to me when he asked how I was shipping it. Thank you. You need to ask the door manufacturer. They will know if their doors can be safely shipped by air. My Question here is: 1. There are a lot of really bad incorrect responses in the Quora link. Hypoxia effects are the same on the body, day or night. At night, we may notice a difference in vision due to the way rods and cones in the retina work.

Most airliners pressurize the cabin slightly just before takeoff. This small amount of pressurization should theoretically cause gasses in the body to be reduced in size take up less space in the digestive system and sinuses. If this small amount of pressurization has any effect on the body at all, it would reduce gas pains the gas takes up less space.

Once airborne, the cabin pressure will slowly begin to drop cabin altitude climbs. The slow drop in cabin pressure causes bodily gasses to expand. I hope her next flight goes better! Field Elev. Setting During the descent the aircraft started to depressurize at 4,ft MSL. Is this normal due to the environmental conditions? Hi Ken, a first class article. I train commercial divers in the UK and often use the analogy of pressurised aircraft to help understand that the partial pressure of oxygen is what sustains life rather than the percentage of oxygen in the mix.

Your article helps make it very clear for many in the way you present it. Forgive me if I borrow some of your knowledge to educate the commercial diving community. A fantastic article, and very well presented, many thanks. I did have one question, however. So, instead of a psi between , it would maybe be even higher at and thus cabin altitude would be lower than k feet?

If the aircraft is cruising at a lower altitude, the pressurization system will provide a lower cabin altitude. A few nights ago we had a short hop on the Our cruise altitude was 24, I think our cabin was about 2, feet. First time reader and thoroughly enjoyed the article on pressurization. I especially appreciate the way you wrote if for fliers instead of engineers! We have the same problems that passengers have.

Same tricks apply to everyone. If your ears need a little help to equalize, holding your nose and gently blowing through the nose usually works for me. Chewing gum can also help. Very Interesting. I was looking for explanation of airtight strength requirements of Pa for High Speed Trains and landed up here. Great Explanation and Very Informative. Great article and conversation. I have been using and flying with an oxygen concentrator I have idiopathic pulmonary fibrosis but I can only get a decent blood oxygen level with it full on 5 litres a minute on short haul propeller flights.

Given that the battery life is limited at 5 litres I needed to know if I should have the POC working while taxiing and in ascent. It appears from the some of the submissions I will only need it at a low level — say, 2 litres a minute — or perhaps not at all.

Am I right Ken? I would feel terrible if I gave you wrong information. Contact your physician or specialist and talk to them about flying. They should be familiar enough with aircraft pressurization and your concentrator to help you make an informed decision. But if I could understand you better, you said aircraft is not airtight as we used to think.

My question is, why is it that an aircraft loses pressure and eventually get crashed when for instance something penetrate the fuselage? Aircraft can still be controlled and safely landed when depressurized.

If you maintain FL and change the cabin interior from feet to feet, you are increasing cabin altitude decreasing cabin pressure. This moves the pressure inside the cabin closer to the atmospheric pressure outside, thus decreasing your differential pressure less difference between inside and outside. The last time I flew was over 20 years ago and during landing the pressure got really bad. I could feel pins and needles all over and my head being squeezed. Is this normal or was there a problem?

Are there people with extreme sensitivity to the pressure and if so, is there anything I can do to make myself more comfortable? The water bottle thing is perfectly normal and will happen on every airline flight.

You drank the water when the aircraft was in cruise. The cabin altitude was probably 6, feet or so. Then you put the lid on empty the bottle. As the aircraft descended, the pressure increased inside the cabin. As the cabin pressure increased, it crushed the bottle.

As for your personal symptoms, I have never experienced them. I would recommend asking your physician. They will be familiar with the effects of altitude changes. Sure Captain I just want to ask you! Can a APU pressurise the aircraft on ground without your engines running. The cabin pressure will never decrease before takeoff.

There are negative pressure relief valves on the fuselage to keep this from happening cabin pressure psi can never be lower than ambient outside pressure.

On some aircraft, the pressurization system will increase cabin pressure lower cabin altitude slightly before takeoff to seal all the doors and increase comfort as the aircraft begins to climb. You can feel this small increase in your ears just before takeoff. As the aircraft climbs to cruise altitude, the cabin altitude climbs pressure decreases at a slower rate so when the aircraft reaches cruise altitude ex: 37, feet the cabin reaches its target altitude of about feet. Opposite happens when descending.

As aircraft altitude decreases, cabin altitude also decreases so the cabin reaches airport elevation at about the same time as the aircraft. I think the Boeing and some newer Airbus models have lower cabin altitudes at cruise. Great article. It is rare that puts Internet in a really good use. Please keep it up! All the best! I am hoping that you can help me find a solution to the following.

I have to fly a lot. However, I have been suffering from barodontalgia [tooth squeeze] on an increasing basis during ascents — not descents over the last 18 months-2 years. Thus I have now been grounded for several months.

By studying altitude graphs, I have noticed that the pain seems to start when the aircraft is climbing and attains 25, feet — at about 15 minutes after take-off and continues for about 30 minutes thereafter whilst the cruising height of about 35, feet is achieved.

Oddly enough, I have discovered that I have not experienced the same problem on inter-continental longhaul flights — for example, Boeing FX ER ]. However, I note that it flew at a slightly lower altitude, the lower 30s for much of the flight.

I am considering experimenting with a series of flights on a Bombardier Dash 8 Q because it only flies to 25, feet. I am guessing that the effects of cabin pressure will not be as severe.

I did a little bit of research and found that the Q cabin altitude at a cruise altitude of 25, is about 8, This is similar to most large airliners at cruise. You are correct that when an airliner cruises at a lower altitude, the cabin altitude will be a little lower.

Most aircraft pressurization systems are designed to keep the cabin at around feet. During an increase in altitude, gasses in our bodies expand which might explain why you have pain only during climb. When descending, those same gasses are compressed as the atmospheric pressure increases. I wish I had some advice to give you. Because you may have a medical problem, the best advice will come from a medical professional.

Unfortunately, they cannot locate the source of the problem, which may or may not be neurological in origin. My personal belief, based upon the fact of the same event happening on two consecutive days, at the same point on different flights, is that there are indeed gasses in my body expanding to cause me the pain — I believe that the condition is called barodontalgia. I have researched various academic articles online in the context of how it affects pilots and aircrews.

My reason for putting up my query on this website is to try and identify the precise trigger. In other words, might it be the rate at which the cabin pressure is changed or the amount by which it is changed, that is causing me the problems? If I may put it this way. You can feel the pen. You know how much pressure you are applying to hold it. It is not painful. You trip and fall forwards. You put out your arms and hands to stop your fall.

The surface on to which you fall is rough. The palms of your hands are grazed and, perhaps, slightly cut. You swear. Slightly painful but bearable. You know that the pain in your hands was caused by the pressure of the fall of your hands on to the rough surface and you promise yourself to try and be more careful in future. You are bound to a chair with the palm of your hand facing upwards. You scream because of the force of the drill going into the tissues of your hand.

You would not wish this experience on anyone. As I stated previously — by examining flight altitude and speed graphs, I have identified two specific points in time during the ascent namely, at about 25, feet during an ascent to 35, feet of two different types of aircraft, namely, the Airbus A and the Boeing F2, on two consecutive days.

Some invisible force then attacks the nerves in my teeth and it is like example 3 above and it lasts for 30 minutes in the whole of my upper right teeth.

I do not believe that the events are purely coincidental. Thus I believe that some aircraft system is engaged either by the pilot or an online computer at that point in the ascent. I understand your frustration. The pressurization system is automated on most every modern airliner. We set the destination airport elevation before we take off and the system takes care of the rest. Let me know how it goes. If not, is the rate of pressurization constant or does it happen more rapidly near the end of the process?

Since the cabin is not sealed, does the pressure fluctuate even minor fluctuations would not be a natural state for the human body , and if so is this more pronounced at altitude? The rate of pressure decrease cabin altitude increase inside the cabin is fairly constant throughout the climb — about feet per minute. If the aircraft makes an intermediate level off, cabin pressure will stabilize. When the aircraft resumes climb to cruise altitude, the cabin altitude will again start to climb at feet per minute.

If the aircraft climbs slowly, the cabin altitude will increase slowly; about fpm. If the pilots need to expedite the climb due to traffic or weather the cabin will climb more rapidly closer to fpm. Cabin pressure controllers have been around for years. The devices have been perfected and control cabin pressure accurately and smoothly. As for the natural state of the human body… Flying in an aircraft is most definitely not a natural state for our bodies.

Even a smooth, fpm climb can be uncomfortable for some. Thanks for breaking out the crayons on this! Heck some people even get altitude sickness in Denver.

But if the pressure of the cabin is equal to 6k-8k feet, some people should have the same effect? Aircraft cabins are maintained at around feet which is well below the altitude most people will experience negative effects. Thank you very much for the comments and the link. It is interesting that all the information on this page bears out what my neurosurgeon told me.

I wondered why he knew so much about aircraft pressurization.