What do you think of a graphic description of the effects of rapid decompression?

[pax domina]

I'll admit it, one of the reasons I read these forums is as a sort of ongoing therapy to combat a fear of flying. I've always been a "knowledge is power" type.

I was following the thread on the problems with the Payne Stewart Lear Jet at
http://www.pprune.org/ubb/NonCGI/Forum1/HTML/010172.html

After all, around here it actually is a *local* story. Halfway down the second page, SKYDRIFTER posted a graphic and gruesome description of death in an airliner by sudden decompression. Perhaps I am being overly sensitive - but I can't see how it added much of anything to the discussion, and in its own way was to me just as offensive as a link to an autopsy web site.

What was the point? To "educate" us that such a death is horrific? That being killed by a piece of flying metal would have been a kinder death? That if any of us are ever unfortunate enough to end up in a situation similar to the one described, we will *inevitably* all die a horrible death?

I considered writing the great gods about this, but figured that with all the brouhaha about the C4 documentary they've got better things to do than listen to the whinging of someone who is, after all, just a stupid passenger. In the past several months I can recall one person from the pointy end venturing down to the bargain basement (and posting amusing replies to queries such as "Why does the fasten seat belt sign always go on just when passengers are finishing their meals?").

On the 19th I've got to fly to ATL, spend 2-1/2 hours on the ground, and fly back to MCO. I have a boss who once announced to all the staff (other staff were on the same flight) that he was leaving early, in order to get to the airport early, to get the first choice of seats on Southwest, so he could sit in an exit row, because "I want to get the hell out while the rest of you are still sitting there burning up." Any wonder why it's *me* who's flying to ATL?

I found the decompression post so distressing that now I'm considering calling off a Spring trip to the Netherlands to visit some of the family who stayed on the right side of the pond. http://www.pprune.org/ubb/NonCGI/frown.gif I suppose I could just get the video of the North American family reunion converted to PAL, and mail it over there. Not quite the same as a visit, is it?

On a more positive note, I loaned my "All You Ever Wanted to Know About Flying, The Passenger's Guide to How Airliners Fly" to a co-worker who is a nervous flyer - she is off with her husband to DFW tomorrow, on a delayed honeymoon. The book certainly helped to turn some of my apprehension in to a fascination with how and why the airliner flies.

[This message has been edited by pax domina (edited 05 October 2000).]

[Herod]

Not a nice story, I agree, and totally unnecessary. Don't put off your trip, it's still the safest way to travel. The chances of an explosive decompression in an airliner are fairly remote, and my guess is you wouldn't know enough to suffer. The general thing is a much slower, and controllable loss of pressure. Unpleasant yes, but not as bad as painted there. Enjoy Europe !!

[Skylark]

Hi Pax
You wouldnt read the PPRUN forum to give you any confidence in flying. I hate getting in the air also. That site you mentioned is pretty ghastly.

[I'd rather]

Pax Domina - all I can say is that I sympathise. I use Pprune in much the same way as you do, and most of the time I find it reassuring. I have no idea what Skydrifter was trying to do with his post, unless it was to exorcise his own demons. Perhaps if he ventures down here sometime, he'll give us an explanation.

I have a constant struggle to stay logical about flying (think of how many people are flying, right now, and they're all just fine - they WILL get home safely, so why should it be any different when I get on an airplane?) Realistically, there are so few incidents and there are so many other, more likely, ways to die out there! Needless to say, none of this is much help when I wake up at 3am terrified because I know I have a flight booked in a few weeks.

I'm booked on a flight for a much-needed holiday in 2 weeks. It's an 8 hour flight, from London to the Caribbean. I soooo want to go, and at the same time, I'm absolutely terrified. Like your trip to the Netherlands, it's something I really want to do, but instead of looking forward to it, all I can think about is the flight. The trouble is, travel is important for me, both for business and pleasure. I'm scared of flying, but I'm even more scared of cancelling a trip, because, having done it once, I don't think I could stop myself from doing it again. And how limited would my life be if I gave into this fear? No more holidays anywhere out of Europe, until I'm rich enough to cruise everywhere?
(the ironic thing is, I'm a shipping lawyer, and I know FOR SURE that sailing is more dangerous than flying!)

Neither of us knows if one day we'll get on a plane that will crash. What we do know is that it's very unlikely. We know for sure that if we stop flying, we won't get to do some of things we want to do. On the other hand, if we do stop flying, there's nothing to guarantee that we won't be in a car crash tomorrow.

Thanks for your post - I feel better knowing there are other people out there that feel the way I do.

Good luck.

[Mycroft]

Apart from what has alraedy been said, that explosive decompression is extremely rare, the gradual reduction in cabin pressure being the problem with the Lear jet, ther is also the fact that it was flying 1t 50,000 ft+, where air pressure is only at 12% of sea level pressure, whereas an airliner flies around 35,000 feet, at 23%. Although this sound low, it would be no problem at all to PAX, as people have even climbed Everest (29,000 ft; 30% sea level air pressure) without oxygen and msot a/c are prssurised at 12,000 ft (60%). In fact as air only contains around 21% oxygen, if you had the masks on you would actually be getting more oxygen than sitting on the ground. I do not believe that any commercial airliner has ever crashed, or passenger died due gradual cabin pressure loss, and I am even aware of 2 explosive (ie sudden) decompression incidents where the a/c survived

[Groundgripper]

There has been one case of decompression that I can vaguely remember which involved a Hawaiian (?) Airlines Boeing 737. In this case a large section of the upper fuselage detached itself and the aircraft effectively became a cabriolet, at least the business class section did. You would imagine that the effect on the entire cabin load of passengers would have been catastrophic, being exposed sub-zero temperature air travelling at several hundred miles an hour. In fact there were surprisingly few casualties, mainly those not strapped in, such as the cabin crew.

I fully understand and sympathise with the concerns of those who do fear flying, luckily I do not - I love it - but do be assured these incidents are very few and far between, that's why they make the news when they do happen. For goodness's sake, don't give up visiting friends and relations or going on holiday just because air travel is involved, it is the safest way of getting around the world. As has been mentioned elsewhere, express your fears to the cabin crew, I'm sure they'll be able to help, you might even discover you've got PPRuNers flying you (now that is a frightening thought!!)

[This message has been edited by Groundgripper (edited 06 October 2000).]

[GalleyWench]

Groundgripper, On the Hawaiian accident only 1 crew member died, all the pax survived. Island hops are so fast they must travel at a much lower altitude. Amazingly, the female first officer was travelling on Uniteds flight 811 that the cargo door blew off !! So much for the odds!!!

[Skylark]

I'd rather,
Is travelling by ship more dangerous than flying? Didnt know that. Actually, I've just booked a train trip to Sydney, then I'm having a couple of weeks off. Its costing a heap, but I'm actually looking forward to the break without having to worry non stop about flying there than flying home again.
I want to go to Europe next year and I have been trying to find a way I can sail from Australia and back again without having to get on an aircraft.

[RossMiles]

Pax Domina,

You know for what it's worth I've been flying (only lt. a/c mind you) for some time now. It's certainly a LOT safter than most other means of transport. And the ATCO's are really clued in you know the chances of any sort of accident are tiny and those a/c esp. the large ones can take a real bashing anyway. I was nervous to begin with but they really are safe. Honest.

Ross
[email protected]

[ExSimGuy]

Pax D,

You've probably heard it before, but I think it may be worth saying again, "the bit you really have to worry about is the M4/M23 (or whatever) on the way to the airport" I've seen some pretty horriffic crashes on the motorway between my present home and the major airport, but there's only been one fatal crash there and that was some 15 years ago before I moved here.

P.S. - I love flying!

------------------
---- "Per Ardua ad Mixas" ----
(Through hardship to the bars)

[Airliner Junkie]

I just stumbled in on this board, and this is my first post. What a great site!!! :)

I am much more nervous in a LARGE TRUCK than an airplane for the simple reason that there are no other cars & trucks to play suicidal games with me in an airplane. ;)

I sometimes go on flights just for fun http://www.pprune.org/ubb/NonCGI/redface.gif, & I will be doing SJC (home) to PHX next weekend for no particular reason. http://www.pprune.org/ubb/NonCGI/redface.gif I'm tempted to go from here to MCO so that I can try out the new 764 that Delta just bought for their ATL-MCO-ATL. ;) I'll be among the first on the new A3XX, and B-747X when it first flies. I certainly wouldn't be spending the bucks $$$ on this expensive habit if I thought that airplanes were unsafe.

Your best bet is to just sit back, relax, $ enjoy the fabulous view of God's Green (& blue) Earth, and the flight as well.

Erik; likes long hauls. http://www.pprune.org/ubb/NonCGI/cool.gif

[Mycroft]

In addition to the Aloha flight above, look at http://www.open.gov.uk/aaib/gbjrt/gbjrt.htm

[Skylark]

The bit where the Captain was `partially sucked out the windscreen' is very reassuring. Reminds me of the the last scene in the Alien movie.

[WAIF-er]

I am a private pilot and am cabin crew with the hope of becoming a commercial pilot.

Last week, I arrived back at Manchester from Turkey. It was a normal 4 hour, uneventful flight, as per usual. No scares, no air rage, very little turbulence, excellent landing in the howling wind and the rain.

The 30 minute drive home from the airport consisted of driving down the motorway, in the dark, the rain lashing down, poor visibility, car being blown all over the place, other drivers going too fast, cutting people up etc.

Since I started flying regularly, I now realise how dangerous driving is in comparison.

You see, fear is relative. If you flew as much as you drove your car, you would soon realise this.

Ask to visit the flight deck next time youre up there, unless you are on a US aircraft where you aint allowed to.

Happy flying.

[Pax_1A]

Skylark - The founders of Lonely Planet run a letters page in the Saturday's Sydney Morning Herald answering all sorts of travel questions. I think they did a few questions recently on travelling by freighter. Doesn't sound fun to me, but apparently there are heaps of alternatives. Unfotunately the web page doesn't seem to give too much info www.smh.com.au (http://www.smh.com.au)

[cap_kirk]

Havnt read the article in question, but I've never experienced decompression in my 15 years of Aviation and rarely heard of"explosive decompression". Of those that have occurred the outcome is often good, thanks to training. Don't often hear of how many people survived horror bus smash do you!
Keep flying its good for you.
Sometimes a little bit of knowledge can be a dangerous thing.

[MasterGreen]

Without trying to sound unduly condescending, I feel that the reactions to decompression on this page are rather ill informed.

I have been flying for 35 years and the only time I have depressurised was on purpose and that was in a military transport to allow people to get out (parachutists). I spent some six weeks in my youth seconded to the Royal Aerospace Establishment at Farnborough England where I was involved in the testing of the high altitude oxygen regulators for the (then) new Nimrod Maritime Aircraft (Can I say this now ? <g> ).

This involved peddling a aerobic cycling machine and wearing various combinations of masks / no masks and being decompressed from 4,000ft to 40,000ft in very short order indeed, many times a day. Well even without the hindsight of practise it isn't that bad. There can be some toothache if you have air under a filling and a sensation rather like when a train comes out of a tunnel - but it goes on for longer. But the worse thing by far is the GAS. In an enclosed space like a decompression chamber this is a very significant reminder to put your mask on <g>. Seriously though, if you have some gas in your gut (and who hasn't most of the time), it will expand and have to get out. If a depressurisation ever happens to you (which is so unlikely that all this typing is probably a waste of time) - the one thing you will remember is the gas episodes. This is why the Guiness Book of Records specifically forbids the use of decompression chambers in the record attempts for flatulence records.

When the decompression is spectacularly rapid then there may be a lot of "fog" since less dense air cannot hold the water vapour as well, and there will be a good deal of noise as the air gets out. However in a large airliner there is so much volume that unless there is a large structural failure (such as the Aloha 737) things will happen very gently. The main point here is that if there is a large structural failure the chances are that the lack of air will be a minor problem by comparison.

The issue of the learjets has been stated. However these aircraft have a double jeopardy in that they have a very small volume and fly very high. However the real problem is the slow leak / failure that is insidious and gets the cabin altitude up with anyone noticing. Or worse still Carbon Monoxide induction.

I would like to address those two points with regards to modern airliners.

The slow problem : All modern airliners have several consecutive safety features to watch out for this problem. They consist of progressive warning states and finally at 13500ft (or so) cabin altitude - and automatic drop down of the masks (the "rubber jungle" in the trade). This is then accompanied by such a racket in the flight deck that it is quite impossible to ignore. As soon as the systems detect a loss of pressure quite a few things happen, and it may be constructive to explain the how and the why of this :

========= Lots of Techie Stuff - can be boring ==========

The B777, as is typical of modern twins, has two airconditioning units (packs). These live in the forward wing roots and are driven (note: driven not fed) by bleed air from either the engines or the APU. The packs take outside air and condition it (depending upon altitude) to a suitable temperature and density to be fed into the cabin. The details of zoning and temperature control are not really relevant here. What is significant is how that air is moved around and controlled to achieve pressurisation and flow through the length of the cabin.
In Pressurisation 101 we learn that the cabin is a closed tube which we then pressurise to a nominal 8 to 9 PSI differential (between the inside and outside air). This equates roughly to a cabin environment equivalent to 8000 ft AMSL (Above Mean Sea Level) when the aircraft is at its' maximum certified altitude of 43100ft. Since the 8 PSI diff is maintained throughout the flight envelope, proportionally lower cabin altitudes are experienced when the aircraft is flying below 43000 (which is most of the time - except perhaps when very empty and at the end of a flight). This constant relationship between cabin and outside altitudes explains why the aircraft can descend from 40000 ft in 20 mins (2000 ft/min) and the cabin comes down very gently at around 300 ft/min (6000 / 20).
As was mentioned before - 8000 AMSL sounds a lot, but for a normal person, particularly at rest, it is a non event. If you were not used to 8000ft and you started exercising then you would puff sooner than usual. However as anyone who has been skiing will know it is not a problem, in fact it is probably good for you. The maximum cabin that passengers can be subjected to by law is 10,000 ft (local mileage may vary). As an aside, the "Rubber Jungle" (drop down masks) deploy automatically at around 13,500 ft cabin altitude.
But I digress (as usual) - back to the mechanics of it all. This 8 PSI differential in the fuselage is achieved by a constant INflow of air from the packs and a controlled OUTflow of air through Outflow Valve(s). The 777 has two, the 767 / 757 have 1. When there is one OV it is in the aft body floor and the 777 has the extra one just below the front door on the left hand side. Why has the 777 got two OVs - well it has multiples of nearly everything else - why not. Seriously though it is a large cabin and flow patterns are improved with a pair. It is also not totally unknown for an OV to jam - so there is an added bonus for control. The normal settings are that the aft valve is 80% and the forward valve is 20% of the required discharge. (Doesn't this drag on ...)

============ End of Techie Stuff ==========

All that said was that there is lots of redundancy in the system and even a pax window going out (and I cannot recall an incident of that) will not cause any drastic problems. The outflow valve(s) and packs will most likely take up the slack and at worst produce a gentle cabin climb. Sure the crew will have to do a descent (and these can feel quite steep - but that is the idea after all), and you may end up having a short holiday in a place you have never heard of at the airline's expense - but that is about the worst of it.

Carbon Monoxide : The only place that excessive carbon monoxide can come from is the engines. All but the smallest airlines DO NOT use engine air for cabin conditioning. The air from the engines is used to power the conditioners, but that engine air does not get into the cabin - what you get is what is outside, smells and all. As an aside - if you have a good nose you can smell turbulence. Well not the turbulence as such, but the clouds that often cause it. It goes like this. In clear air at altitude the air is very dry and the filters on the air conditioner packs dry out. As you enter cloud the moisture content increases and some of the dust on the filter screens releases a "dusty" smell. It's not unlike turning on an A/C at home that hasn't been used for a while - and that is very close to the smell. It's subtle, but see if you can spot it next time you fly. Now that there is no smoking in the aircraft (hooray) it is a lot more obvious even above the body odors, cooking smells, deodorants and what have you.

I have droned on for so long - I have forgotten where I am or where I was going with this <g>.

The penultimate issue is the one about time of "useful consciousness" that is often misquoted. Let's try for a few facts. There are lots of tables published for different altitudes and conditions, but who commits this to memory or has time to look it up if it happens. The bottom line is 20 seconds would be a good figure to remember - and that is if everything is in the worse case. The aircraft is very high, the depressurisation is total etc etc. 20 seconds to put on your mask. Just sit there and count out twenty potatoes and imagine taking hold of the mask, pulling to activate and putting it over your face. It may not be wonderfully adjusted, but that is not a problem at all. All you need is a little supplemental oxygen for a few minutes - not a space suit. Your blood is not going to boil or your lungs explode or anything drastic like that. If you have a bad head cold then you are in for an earache - but more likely on the way down (see below) and you will certainly be well on the way for a record breaking "wind" event - but then so will everyone else, so no prizes. There may well be some noise and mist in the cabin. The aircraft will also be starting down on it's descent. All this is pretty expected - almost normal - but it's too easy to say that. There will be much alarm and even some panic which is just what isn't needed, but that is human nature and nothing can change that much.

Lastly then, the descent. When it's all over the pilots have to get the aircraft down to the ground again. This will involve bringing the cabin down much further than normal (6000ft) and there are greater than normal pressure changes. They will do this as gently as possible to avoid giving everyone (themselves included) earache. However the crew are well aware of these problems and will have a remedy. In the worse case the aircraft can be leveled to allow everyone's ears to equalize. The big thing though (should this ever happen) is to speak up early. Young children can be a problem here also, but they will cry when they get uncomfortable and a suckling will nearly always do the trick.

But enough already.

Oh, when you are going flying, worry about the important things. Did you get ripped off on the Duty Free ? Did you put the cat out ? that sort of thing. Certainly don't worry about a depressurisation. The worst that might happen is that you might need a change of underwear <g>.

Finally my tips for a good long range flight :

1. Don't drink alcohol, drink lots of water instead - the cabin air is dry enough to turn your throat to leather and your kidneys to golf balls. Don't make it worse.

2. Always keep your seatbelt loosely fastened, even if the sign is off. Double so for the kids.

3. Don't over eat and stay away from heavy or spicy food.

4. Always carry a wash bag (teethy cleans and a shave as required) and a change of underwear. (See above spicy food and gas).

5. Same as tip #2

6. Sleep with a moist towel near your face (see #1)

7. Loosen shoes, ties and girdles (as required)

8. Take a good book, since the most common "in flight emergency" in my experience is the total loss of the "in flight entertainment system". Or worse I have seen all the movies.

9. Same as tip #5

Relax and enjoy your trip ....

MG.

[I'd rather]

Mastergreen - thank you so much for taking the time to post - nice to see something both illuminating AND reassuring! Can't tell you how much it means to a (very nervous) pax like me. I shall think about your wise words when I'm boarding the aircraft on Friday - thanks again.

[Skylark]

Yeah..ok.. so decompression has been sorted out - but what if a wing falls off??
Do us a story on `wings'

[pax domina]

Thank you so much, MasterGreen! One of the things I like most about this site is that it is often informative *and* entertaining! (Someone better not tell Howard Stern about decompression chambers and wind, or we're in for something *far* beyond the broccoli and cauliflower fueled serenades we've been hearing up until now!)

A little knowledge *can* be dangerous - but I'm a firm believer in "better the devil you know". Throughout my life (and to the despair of my teachers), I've always been one to read up and investigate things that interest me. (nb - This did not always coincide with what the teachers were trying to teach me!)

*Never* trust the IFE. Learned this the hard way on long haul HNL-ORD. The tape loop (they were probably using 8 tracks back then!) featured as its last "track" a *minute* (I guess they ran out of space) of what was then one of my favorite songs - Steely Dan's "Deacon Blues". No such things as Walkmans (or were they outrageously expensive?) back then . . . and eight bl@@dy hours of the song fading out *just as it got to the chorus*!

So I learned early, bring your own IFE! Usually a book, or some old fashioned, no batteries required, entertainment - these days often a puzzle manufactured by Binary Arts, or my portable "tangoes" set. (On one recent flight the lady sitting next to me expressed an interest in the tango/tangram I was trying to solve. I gave her the second set, we set about solving some of the puzzles together, and the time, um, *flew* by!)

Of course, it *was* Transatlantic IFE that introduced me to Wallace and Grommit!

Your mention of the Nimrod - as pictured on page 125 of Jane's Aircraft Recognition Guide, so it must be okay to mention it now! :) - reminded me of a story my father (retired US Army Signal Corps) just told me about the U-2s based at Hickham AFB in Hawaii in the late 1970s. They only ever took off and landed at night . . . and even then they went right in to the hangar and the doors were closed. He also mentioned something about J-8 fuel, which was so thick it was like jelly . . . but he was a ground type, so what does he know! :) (He says he knows nothing about Military aircraft, but he seems to be able to point out in a heartbeat the ones he has flown in. "But didn't you at least have to know the difference between your stuff and the other side's stuff?" Apparently not! Well, when I mentioned Boeing RC-135 at least he knew enough to say "spook plane".)

I never was quite sure what the Hawaii job (CINCPAC J6-2) entailed, except that sometimes the hours were strange, sometimes he had to go out on a sort of spook ship which had a lot of strange antennae on it, possibly he knew something about bits of hardware hovering very high above the earth looking at things the "other side" was doing, and he got to go to Australia once. Maybe that should be he *had* to go to Australia once . . . it was *July* and he had to spend time in the mountains. He said "I froze my @ss off!" That, and we could always tell when he went to the USMC (Marine) barbershop at Camp Smith, because he returned with a very short neo-jarhead haircut. :)

But I digress! I'll just add my thanks to that above. Thanks for your visit to the "bargain basement", it is much appreciated!



[This message has been edited by pax domina (edited 17 October 2000).]

[You splitter]

All of the poeple that have pointed out that driving the car to the airport is the most dangerous part of your journey are spot on.

Flying is the most safe way to travel. No question about it. The industry has worked very hard towards safety, and is for the most part self-regulating, as airlines take the whole issue very seriously. We have to.

For those of you are nervous flyers, there are several airlines (BA being one of them) that operate courses on the whole subject. The evtual goal being a flight, usually lasting about 30 mins. they will explain the physics of flying, how a modern jetliner works and also what steps are taken to ensure the safe operation of the aircraft. Apparently feedback has been very good. Don't know how or where you find out about them, or even how much they cost. However, if you are nervous and have to travel often it may be worth making enquiries.

Once you get over that fear I'll bet you'll enjoy the whole experience and can't wait to be starpped in again!

[I'd rather]

Yes, I've heard about the fear of flying courses and I actually promised my other half that I would go on one - haven't quite got round to it yet, but they do sound good. Oh well, the real thing tomorrow instead. I shall think of everyone's kind words during the 8 hours to Antigua and hope to be back with you in a couple of weeks winding up Capt Ed, Tartan Gannet et al!

Thanks again for the kind thoughts.

[pax domina]

Thanks to your kind thoughts, I am now back from what were a couple of calm and nearly anxiety-free flights to and from ATL!

Good luck tomorrow, I'd Rather!

A DHing flight deck type mentioned something about "discovery" fights offered at flying school locations. Also, the book I mentioned above did a great deal to calm my fears.

I'll post more details about the flights above . . . the first flight was by far the most unpleasant! Packed in like a sardine and some of *the worst* "unprofessional" pax I have encountered. :mad: At least I was only going to ATL . . . the a/c was continuing on to Sacramento, California! UGH!

The flight back was (an equipment change from what had been originally scheduled) on an almost brand-new 777. I'll post my "technical" question about a flappy-floppy bit on the 777's wing above.

Hooray!

[Hand Solo]

For those of you who read the story about the Captain sucked out of the window, you may be interested to know that both the Captain and the FO still fly for BA, as does one of the stewards who is still based at Birmingham and still does Malaga charters!