When is a plane pressurized

The airplane already has a huge hole in it called the outflow valve. And air marshals are reputed to be excellent marksmen. Continue or Give a Gift. Daily Planet. Flight Today. History of Flight. Virtual Space. Related Content What happens if an airliner suddenly loses cabin pressure?

Like this article? Comment on this Story. Last Name. First Name. The crew will likely turn on the APU as soon as they see the engines failing. In the meantime, the crew will have the aircraft in a controlled, gradual descent as they run through the engine restart checklist. Once the engines are running again, normal pressurization will be restored. The good news is that this has never happened on an AeroSavvy AS A very nice read. Ken…follow you on Twitter and enjoy your Tweets and these articles so much…I live my aviation fantasies vicariously through you…thanks so much…a Canadian fan.

Thanks Ken This article explains aircraft pressurisation so clearly. I have forwarded the link to my book group. One of the members wondered why her smuggled boxes of eggs burst in her hold suitcase.

Were they raw eggs? Eggs have very little air inside of them which should make them fairly immune to the pressure changes in an airliner. If she checked her bag, it was likely the baggage crews that caused the eggs to break. I recently flew on a for the first time. I was hoping that the extra cabin pressure on a would help my symptoms from sinus issues be less apparent.

By midway of the long flight I had all the various pain issues that I associate with sinus problems while flying. This made me wonder if the actually is flown at the advertised pressure you see in the literature or airlines can set the amount as they see fit? I also realize that my discomfort might be from something else; dehydration or just sinus problems not related to the pressure. Even though the system is an improvement over older systems, it still does not maintain a ground-level cabin pressure.

While a typical airliner might maintain a foot cabin altitude, the Dreamliner has a foot cabin. While this is a big improvement, someone with sinus problems will likely still have problems in a You might check with your doctor before flying again. He or she may be able to recommend something like a Benzedrex inhaler that will help relieve your discomfort. I see an aircraft pressurization system advertised as 5.

Is there a chart or formula which would indicate the cabin pressure versus sea level pressure at 5. Yet I have been unable to find a chart. If you were in a 5. If the 5. Airliners typically run about psi differential pressure at cruise differential pressure is the pressure inside the cabin minus the pressure outside. The various versions of the Piper Malibu it has a maximum cabin pressure differential between 5.

Because they fly at a much lower altitude the lower differential is not as much of an issue as in an airliner. Military tactical aircraft are typically pressurized to a 5. Great question, Ben! The very first aircraft with pressurization was the Airco DH. In , this redesignated aircraft, the US D-9A, flew the first high altitude pressurized flight. How are air crew and passengers in commercial airlines, without filtration or detection systems warned, protected and informed in the event of a fume incident from contaminated bleed air?

On the aircraft I fly, there are no detection or warning systems to let us know of contaminated bleed air. There are only a few things that can contaminate bleed air. Occasionally, deicing fluid can get into the system; we have procedures that we follow to minimize this risk. The very small amounts that get in the system usually through the APU inlet are not hazardous.

The large amount of fresh air flowing through the system quickly dissipates the residual vapor. Sometimes vapor from engine lubricants can find themselves in the bleed air system as the engines are started. Again, the small amounts of vapor are quickly eliminated from the system by the huge quantity of fresh air being moved through the aircraft.

The crew has a checklist for this and the system responsible for the problem will quickly be shutdown. 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.

That's why that negative pressure relief valve is much more sensitive. That's the negative pressure valve kicking in. In the rare event that depressurization fails during a flight, there are other safeguards, Horning notes. There's a sensor that detects when the pressure declines to the equivalent of 12, feet 3, meters in elevation. That switch automatically drops oxygen masks into the cabin, so that the passengers can continue to breathe without difficulty.

In some aircraft, the oxygen comes from cylinders, while others get it from generators that release oxygen through a chemical reaction. Sudden depressurization is depicted in the climactic moment in the classic James Bond movie "Goldfinger," in which the pressurized cabin is punctured and the eponymous villain gets sucked out a window to his demise.

That's going to create a pretty good disruption inside the cabin. You're going to be disoriented. The scene in the movie may have overdone it a bit, though," says Horning. Sign up for our Newsletter! Mobile Newsletter banner close. A plane-ful of panicking passengers, many of whom awoke from naps to discover intense pain in their ears, bleeding from their ears and noses, and a heck of a lot of confusion.

Air at higher altitudes is under less pressure and is therefore harder to inhale—the molecules of oxygen are literally farther apart. The same thing happens in reverse at the other end to bring everything back to normal.

Your body is really only designed to work within a small range of pressures pretty close to sea level, and when you go outside that zone delicate areas get damaged. Fluid and gas are both far more susceptible to pressure than solid flesh, so these bits go first. You actually experience a minor version of this in airplanes or even in fast-moving elevators: your ears pop. Changes in pressure can block the Eustachian tube, making a tiny, painful vacuum in that inner ear bubble.

Chewing gum or even sucking on a hard candy alleviates that issue because the act of swallowing opens up your Eustachian tube. All this is to say that your ears are very sensitive to pressure changes, so bleeding from the ears might not be all that surprising given the lack of pressure on this aircraft. Similarly, delicate blood vessels can rupture in the nose. Large aircraft are well equipped to handle this, because air masks drop and provide enough oxygen to for the pilots to get the plane down to 10, feet or below, where the air is dense enough to keep everyone alive and functioning.