Pressurisation

[bubblesqueaker]

Hi,

I was wondering if you experts could answer a question for me?

We flew home on a 747-400 from the US this morning followed by a domestic flight on an E195. the 747 flight was fab although on the E195 final descent my husband had awful pains in his face which resulted in us having to go to hospital.

The Dr had suggested that it was most likely due to pressurisation and lack of oxygen. Is this common and do you think I should contact the respective airline?

It may be totally irrelevant but I did notice midway that at one stage the air conditioning and overhead blowers were blowing out hot air.

Thank you in advance :-)

[CHfour]

I think we can rule out lack of oxygen. I'm not familiar with the 195 but used to operate the 135/145 and they had excellent pressurisation controllers and ear discomfort was never an issue even if you had a cold. Very occasionally the automatic system can fail and then the standby or manual system would be used as a back up. It's 100% safe but can cause ear discomfort if mis handled. If, for example, the crew were given a last minute descent clearance and were slightly late reconfiguring the pressurisation panel then you could have ear problems. I'm only speculating, of course, and am not criticising the crew.

[bubblesqueaker]

Totally understand! The crew did a fantastic job. I just wanted to check that it wasnt anything to worry about and could cause a problem for other people.

Many thanks for your time!:)

[SNS3Guppy]

The pain experienced during descent is the result of a pressurization change, and it's taking place in the sinus cavities. I've been hospitalized several times as a result of sinus blockages. In each case, I wasn't even aware I had a blocked sinus. It's seldom a problem when climbing; typically as the air in the sinus expands and cabin pressure drops, it vents out of the sinus easily enough. However, on the descent, it won't re-enter the sinus, and there's a low pressure in there.

If you've ever watched a water bottle on the ride down from altitude, you probably saw the water bottle slowly collapse and crush...the sinus cavity is experiencing something similiar. While the cavity itself doesn't collapse, it can do damage to the soft tissue lining of the sinus, which can separate, and cause an enormous amount of pain.

The rate at which the cabin pressure changes has a lot to do with it, but the overriding factor is the condition of the patient, in this case, your husband. A technique known as the "valsalva maneuver" is sometimes used to allevaite this condition, but it's not always successful. In a nut shell, one takes a deep breath and closes one's mouth, then pinches the nose while attempting to "blow." This pressuirzes the sinus cavities and may help inject some air, to alleviate the condition. Sometimes placing a warm, moist towel over the face can do it too...and back on the ground at home it's often helpful to take a warm shower and let the steam go to work.

A sinus blockage is one of the most painful things I've ever experienced, and had I not felt it first hand, I wouldn't have believed it. It can be completely debilitating. The first time I experienced it, I hear a bang and felt as though someone had smacked me in the head with a cricket bat. It really hurt. I ended up in the emergency room at the hospital twice as a result of that incident. On another occasion, also as a passenger, I was having headaches for a month, and was deaf for that month, too.

I didn't feel sick at the time, before the flights, but it's a good reminder to never fly sick...there's an increased possibility of ear blocks and sinus blocks if one is flying when sick. If it doesn't go away right away, visit a doctor.

[Microburst2002]

No matter how sophisticated an aircraft pressurization system is, if you descend too late and to quickly the cabin can only descend quickly, therefore causing ear disconfort. It is simple maths, elapsed time since begining of descend till landing.
If you add a cough or congestion, you can have your ears damaged.
Many crew members have had problems because of that.
In an airline, many cabin atendants will use the flu as an excuse for not working on a given day (sunday morning, tipically) and many others will have ear problems because they do not want to earn less money or have problems with the company.

[muduckace]

This is no fly call that more should be informed on.

People have suffered due to congestion, blown out eardrums and possibly worse results are possible. I used to push myself when required by my previous employer to fly as a flight mechanic/maintenance rep. The last straw... I was cracking my jaw trying to clear my ears and found myself unable to equalize during descent, I staggered for several hours (equilibrium).

I made it to the bar to meet up with some friends I had planned on meeting and after about an hour (beer in hand) heard a squeel out of the pressurized ear and turned to my buddy and told him I just landed. After that I started rejecting flights if I was congested understanding the damage it can do.

This post was intended to be humorous and serious..

[SNS3Guppy]

This is no fly call that more should be informed on.



Say again?

[sb_sfo]

Maybe it should read as "This is a no fly call...:O

[toolowtoofast]

With a max cabin alt of 10000', and probably actually of only 8000', there is only a requirement to descend the cabin for 16-20 minutes, to keep it comfortable at 500fpm. It would be unlikely to have to descend it any quicker, and I would think most (except babies and the obviously unwell) would not be able to equalise. It is more than possible that you have had blocked sinus - not hard in the dry atmosphere of the px cabin. I always chew gum when I'm flying (and i do plenty of sea-level to 12000' and back) and don't have any trouble unless I have a hangover or a cold - then it hurts :( I do get very doughy though after a dozen climb/descent cycles

[Dimitris]

A technique known as the "valsalva maneuver" is sometimes used to allevaite this condition, but it's not always successful. In a nut shell, one takes a deep breath and closes one's mouth, then pinches the nose while attempting to "blow."

SLF here, a trick that works for me when one ear is blocked (usually the case), is to pinch the nose, and the unblocked ear with a finger and then ''blow''.

[GlueBall]

No matter how sophisticated an aircraft pressurization system is, if you descend too late and too quickly, the cabin can only descend quickly, therefore causing ear disconfort. It is simple maths, elapsed time since begining of descend till landing

This is true only in a non pressurized cabin where cabin altitude equals airplane altitude. When packs [Air Cycle machines] are operating normally, cabin altitude rate changes are controlled, typically at no more than 250 to 500 feet per minute. Even when the airplane descents at 4000 feet per minute, it wouldn't affect the cabin rate of change. In a B747 at 35,000 feet with 3 packs running, the cabin altitude would normally not be above 5000 feet. So, descending the cabin from 5000 feet cabin altitude to sea level altitude at 500 feet per minute would take only 10 minutes. A "late airplane descent" from FL350 would be inconsequential. :ooh:

[SNS3Guppy]

SLF here, a trick that works for me when one ear is blocked (usually the case), is to pinch the nose, and the unblocked ear with a finger and then ''blow''.


Dimitris,

That's the valsalva. Plugging your ear, however, won't make a difference, as there's no air passage through the ear, to block with your fingers. You can plug your nose and pressurize your sinus cavities and the eustachian tubes by "blowing," but plugging your ears shouldn't make any difference.

Don't rely on that technique to relieve a pressure imbalance, however. If you find yourself blocked, or your sinuses plugged or with ear pain, don't fly...the passage between the sinus and your airways, and the eustachian tubees are very, very small. They can easily become occluded when you're ill, and it's very possible to get to a point in flight where you can't relieve the pain. A blockage can become incredibly painful, and can cause separation of the lining of the sinus cavities as well as eardrum rupture.

The solution, of course, is to avoid flying if you're ill, or supsect you might be so (even if you don't feel it yet). Better safe, than sorry.

[Microburst2002]

GLUEBALL

Physics and maths apply to both unpressurized and pressurized airplanes.
If you have to lower the cabin (pressurized or not) from say 7,000 ft to sea level, the rate at which you do it depends solely on the time it takes, that is: the elapsed time since the TOD to touch down.
No matter if you use the most sophysticated pressurization system or are in a cessna C172.
If, instead of beginning descent at the computed TOD, you wait ten minutes and then you make an emergency descent at MMO/VMO with speedbrakes extended you will have very high a cabin V/S because the system has to reach sea level in less than half the time it had planned for a comfortable cabin rate. The rate will be twice as much!
Besides, you would probably "reach the cabin" before landing.

[GlueBall]

Are you a cadet pilot? Understand that there is no way, even for a test pilot, in a large transport category airplane to go from TOD at 35,000' to touchdown in only 10 minutes. You would need additional time to slow down, maneuver to line up, configure flaps. Even if this could be done, [airport and runway exactly where you want it] the cabin altitude would still be able to descent at a normal 500fpm from 5000' typical cabin altitude at FL350 to sea level in those 10 minutes; even during emergency descent at VMO and 6000' per minute. The cabin rate of descent has nothing to do with the airplane rate of descent, the packs don't stop working when the thrust levers are retarded and descent is initiated, the cabin rate can be manually set at whatever you want. As I said, you won't make it to touchdown in 10 minutes. But you can descend the cabin from 5000' cabin altitude to sea level at 500fpm in 10 minutes! Not an argument, just a statement of fact. :ooh:

[Old Fella]

In the "good old days" when they were still building aeroplanes with a F/E station, normal practice was to descend the cabin at, ideally, 300'/min. Among many things in which F/E's took pride one was to make the descent of the cabin altitude to landing field elevation, whatever that may have been, as indiscernible as possible. Most times when I have experienced discomfort from pressure changes it has been in aircraft with no F/E. BTW, this not a criticism of pilots, rather of "automation". Those who flew the B707 will especially know what I mean about the value of having a grey headed old bugger looking after the "Environmental Systems".

[Microburst2002]

Dear Glueball

The average cabin rate of descent during a descent exclusively depends on the cruise cabin altitude, the airfield pressure and the descent time.
No matter if you have packs or are flying in Von Rishtoffen's Fokker. In the 747, an automatic system will manage the outflow valves so that the cabin V/S will be confortable (typically 350 fpm). In Von Richtoffen`s Fokker it is the airplanes V/S which determines the cabin rate. In both cases, the TOD can be a factor affecting the location of the TOD, or the descent method.
From 7,000 ft to sea level in 20 minutes the rate is 350 fpm. If you descended those 7,000 in only 10 minutes (I know this would be quite a kamikaze descent, but please allow me such didactic treat) then the average rate would be 700 fpm. Many cadet pilots understand this the first time I say it.
No matter what you do or what kind of plane you are flying you have to reach sea level pressure before landing. You cannot land in 10 minutes and wait another 10 until the system reaches sea level pressure. That is the problem. That is a reason why some airplanes cannot descend at idle all throughout the descent but they have to maintain a given vertical speed or thrust setting until reaching a FL from which they can retard the throttle levers. If they didn´t the target average cabin rate would be exceeded.
It is a fact that if you descend too fast ( or faster than planned) you will have a higher cabin V/S than planned. Even at 500 fpm you may suffer pain if your ears are sensitive. In addition, when the average cabin V/S is high there are peaks, so an average 450 fpm descent can be 300 fpm in the beginning and over 550 fpm at the end (this is the moment when the little babies cry).

[deagles]

I seem to remember that the HS125 had a rotary selector for cabin descent rate. if you descended fast you might have to delay opening the door before shutting off the engines.

[minstermineman]

Quote:
SLF here, a trick that works for me when one ear is blocked (usually the case), is to pinch the nose, and the unblocked ear with a finger and then ''blow''.
Dimitris,

That's the valsalva. Plugging your ear, however, won't make a difference, as there's no air passage through the ear, to block with your fingers. You can plug your nose and pressurize your sinus cavities and the eustachian tubes by "blowing," but plugging your ears shouldn't make any difference.


Correct - wont make any difference to the equalising of air pressure - but plugging or sealing the UNBLOCKED ear will protect the eardrum of that ear from overpressure caused by the Valsalva maneouver being used :ok:

[BOAC]

It is a fact that if you descend too fast ( or faster than planned) you will have a higher cabin V/S than planned. Even at 500 fpm you may suffer pain if your ears are sensitive. - you are not reading Glueball's post correctly! The Rate of Descent of the cabin is FIXED by the manufacturers at a figure - 500fpm is typical. A rapid descent does NOT increase this. You can, however, change the rate of descent of the cabin by selecting a different rate on the panel if you wish. It doesn't matter if you come down from 35000' in 1 minute or 15 - the cabin will descend at 500fpm. What THEN happens is (as you say in one of your posts) - you 'catch the cabin' ie the cabin pressure is such that the INWARD relief valve opens (designed to stop the hull squashing like a coke can) and the cabin THEN descends at a higher rate (which is often painful to many) until it is back in 'normal' range.

If anyone suffers 'pain' at 500fpm then they are stuck because that is what they are going to get! There is little a crew can do to correct this rate. I once had to level off and select a lower cabin rate (and slower descent) to cope with a medical problem but it is unusual. There are other 'tricks' to help with rapid descents - but not for this forum.

Incidentally - the best way to cope with 'sticky ears' is to ensure you start Valsalva either just before or very early in the descent rather than wait until pressure has built up in your ears. If you remember that the cabin does not normally start descent until a thousand or so feet below cruise, then as soon as you hear the engines throttle back, start puffing! Yawn as well.

I am not convinced at all by 'minstermineman's' theory - the pressure Valsalva generates is insignificant.

I speak from a painful experience when as a young inexperienced QFI I agreed to do circuits (1000') with a bad cold due to shortages, thinking it would be fine. I can assure you the last 1000' is the worst - that is where my ears blocked:{

EDIT: Thanks to FE Hoppy I now know the AB programmes up to 750fpm max R of D.:ok:

[FE Hoppy]

Some more modern pressurisation controllers use a variable rate of climb and or descent depending on a number of factors including Take Off Weight, Take Off field elevation, Cruise altitude and landing Field elevation. With known time schedules the px controller will choose the appropriate rate from within a range. A typical maximum descent rate would be 750slfpm but more likely the rate will be less than 500slfpm. When this data is not available due to FMS failure or just not programmed the system will vary the cabin px depending on the outside px. This will give a varying rate of cabin climb/descent depending on the aircraft rate of climb/descent.

FE's do it manually with one hand. :)

This FE can generate enough pressure when valsalving to blow air out of his tear ducts. Very amusing when pressure breathing in the chamber.

Mate had blocked Eustachian tubes in the chamber one year and ended up with bi-otitic barotrauma. (both his eardrums burst). He had to have grommets fitted in his eardrums but it pretty much ended his flying career.

Otravine is very good if used 20 minutes before TOD but as pax you wouldn't know when that would be.

The finger in the ear (over the ear) does work and was told to me by an RAF aviation medicine specialist.

As for the OP I got the feeling this was a trawl for some ammunition to use against the airline (Flybe?). Sorry this isn't their fault. If you had brought it up at the time they could have reduced the descent rate to assist. And the system i described above is that used in the Embraer E-Jets.

[Capt Pit Bull]

BOAC / Glueball

The Rate of Descent of the cabin is FIXED by the manufacturers at a figure - 500fpm is typical. A rapid descent does NOT increase this

Of course it does. If you do a dirty dive the aircraft altitude can overtake the cabin altitude, at which point the inward relief valves will open and the cabin altitude will experience whatever rate of descent the aircraft is doing.

pb

[BOAC]

Cpt PB - you did not read our posts properly, did you? I and GB said a rapid descent does not change the manufacturer's FIXED maximum rate. Try my para 1 again, especially the bit after 'What THEN happens is....' ?

[Microburst2002]

BOAC
I understood GlueBall, only I disagree with him.
I know there are many different cabin pressure controlling systems for airplanes.
However, if it is required that airplanes reach field pressure before landing, the time to descend from crusing level to the airfield is the same as the time to increase the cabin pressure from its cruising value to airfield's.
So we have a time (descent time) and a pressure change requirement. These determine the average cabin rate of descent. Rapid descend, faster average rate. Slow descend, slower average rate.
As Captain Pitbull clarifies, if the cabin rate is fixed by the system and you dive like an Stuka, you will either reach the cabin (and from then on the cabin and airplane's rate are equal) or land with differential pressure greater than zero. I think that after touch down, the outflow valve will open in most airplanes, so in the latter case the cabin would unpressurize very quickly after landing.
The result would be in any case a faster average cabin rate of descent.

I do Valsalva very often and always block the other ear, otherwise can be harmful. I prefer doing it very slowly, too.

[Microburst2002]

OK BOAC
The fixed max rate, now I got it. But things remain the same. You can hurt your ears descending late and fast.

[Capt Pit Bull]

BOAC,

You're correct, I didn't read the rest of your post. My apologies.

I don't think it makes any difference though; it is still factually inaccurate to state that the maximum rate is FIXED. It isn't.

pb

[BOAC]

No probs! I think we will have to agree to disagree there. Perhaps if I said 'normal programmed max rate'.............? I don't know of any a/c where if you start a screaming descent at 10,000 ft per minute the cabin instantly follows you down (screamingly:)) at a high rate. Maybe I'm out of touch.

[SNS3Guppy]

I don't know of any a/c where if you start a screaming descent at 10,000 ft per minute the cabin instantly follows you down (screamingly) at a high rate. Maybe I'm out of touch.


You're not out of touch. Excepting a massive breach of the pressure vessel (eg, missing door, hole in the fuselage, etc), even a rapid descent with bleeds off or power insufficient to provide adequate bleed, the cabin rate will not follow the aircraft rate. If it did, there's no way the aircraft could ever pass a leakdown test or be considered a pressure vessel..even with the dump valves open and/or negative pressure relief valves open.

Leakdown tests today are mostly performed on the ground, but certain older aircraft still use airborne leakdown tests at a specified altitude. With cabin pressure set to a known value, bleeds are shut off and the rate of cabin change timed. Even with the bleeds off, there's no instant dump. If there is, and if the pressure vessel is leaking so sufficiently as to allow the cabin to change rapidly (eg follow the aircraft rate of climb or descent), then there are serious problems with the sealing of the pressure vessel.

[BOAC]

SNS - my posts are about controlled cabin rates of descent, not 'leak rates'. I would have thought that any a/c that allowed a programmed high rate of cabin descent would cause significant complaints from our salary payers. The cabin crew would need earplugs to block out the screaming. :)

[Capt Pit Bull]

<nod> fair enough ;)

btw... to all concerned...

The valsalva can really mess you up. I'd been using for years. I eventually had a load of ENT trouble. When I went to see 'the man' and described my history he tutted a lot. Basically forcing pressurised air around those tubes and cavities is not recommended. Since I had festering puss emerging from my tear ducts I was forced to concede he might have a point!

pb

[Microburst2002]

Catpain Pitbull

So is there any solution for sensitive ears?
I do a lot of valsalva!:eek:

[BOAC]

Cpt PB - so glad I had finished my lunch:)

Micro - nasal spray, solid inhaler stick, don't fly with a head cold or sore throat if you are 'sensitive', learn to 'exercise' the openings of the Eustachion tubes in your throat (practice 'ear wiggling' until you hear the eardrums click - when you don't have a cold). None of them 'foolproof'. Check the med forum here for more on the topic. I fully endorse the warning CPB issues - frequent VS can force infection/germs into the tubes which are there purely to allow pressure equalisation. I have just finished 45 years of professional aviation having 'small' eustachion tubes (according to an RAF ENT specialist). There have been times when life has been difficult.

The primary secret is to keep the openings 'open', since like any 'soft' opening they tend to close up under positive external pressure.

The very worst is sinus blockage which is what I assume the OP's husband had on the second flight. VS does not normally help with this. The pain can be excruciating and can cause you to pass out. Repetitive cycles of 'ear problems' (and almost certainly dodgy sinus 'openings' at the same time) can cause scarring of the damaged sinus drain tissues and then they can definitely block. All good fun, yes (and VERY interesting when on your own with 10 minutes of fuel remaining....)?

[Microburst2002]

Thanks for the advice!

[SNS3Guppy]

SNS - my posts are about controlled cabin rates of descent, not 'leak rates'.


I get that.

My point is that not the cabin won't follow the aircraft down in a high rate, even with the bleeds off...it's going to lag. With a pressure controller doing the work, it's going to be a much slower rate of change.