Virgin's Presurisation

[jindavik]

I have just seen my G.P. He had 4 passengers from Virgin with severe ear problems involving bleeding from the inner ear over the last 6 months. He was interested in whether Virgin do anything diferent. As a longtime G.P he was curious whether Virgin do anything diferent? Any comments?

[Prop's ????]

What sort of question is this?

B737-NG pilots do not operate the aircraft pressurisation controller independently; they simply enter the CRUISE and LANDING ALT.

The pressurisation controller calculates when to climb and or descent.

Ask your self this, if it was a VB fault, then why haven’t they had complaints before this one.

[jindavik]

Props This is a geniune question which I could'd answer .I am not gunning for virgin but he did sugest it was more than a coincedence.

[A.H.]

Does this mean all operators set their pressure at the same height? I think not !
Why is Props so Bl**dy angry at a simple question ? Does he /she know something we don't?
A.H.

[Raider1]

Well Virgin certainly has a policy of flying higher. Not sure if this has anything to do with it.
Last sunday night paxed Virgin BNE CBR. QF and DJ left almost same time. DJ arrived CBR 15 min after QF after flying in the high
30's.

cheers

[Prop's ????]

jindavik

I believe I have answered your question.


A.H.

Don’t be so touchy; I am not angry at jindavik, but at question asked. Every time an inexperienced passenger has a problem, it always becomes the operator’s fault.

Not long ago, a family member called me and advised me that she would never fly VB again. When I asked why she said, “The cabin crew made her return to her seat while she was in the toilet. They then refused to warm her babies milk bottle,” I then asked her what was happening at the time she said, “The aircraft was on approach, but didn’t land for at least 3 minutes.”

As far as I am concerned, the crew did their job.

[jindavik]

Props I am not a pax. I have 10000 hrs with jet time. I was just wondering wether you guys tweek your presurisation system any diferent? To be honest I was intrigued by my Doc's question.

[HotDog]

Pathetic! What a load of cr@p. You guys haven't got a clue what you are talking about. By the way, I have 20,000 hours in various jets.:rolleyes:

[BankAngle50]

Is this for real? Perhaps it’s not just a stab at VB. If not;

The B737NG Pressurization system works as follows (as per Vol 2 2.40);

“In the AUTO or ALTN mode, the pressurization control panel is used to preset two altitudes into the auto controllers:
▪ FLT ALT (flight or cruise altitude).
▪LAND ALT (Landing or destination airport altitude).”

So as you can see it’s as simple as that. This is verbatim from the Boeing manual and cannot be “Tweaked” in any GA’ish kind of way. You would only use Manual in non-normal situations. Hence I guess QF NG’s must have problems as well considering the aircraft come from the same factory and use the same pressurization system from Mr. Boeing!!!

Perhaps DJ encounters some mysterious atmospheric anomaly with their pressurization system, which the incredibly talented QF 737 pilots manage to avoid on every sector? Jindavik I have bothered to provide you with the facts above assuming your question is legitimate, no matter how foolish, nay ignorant it portrays you. If you are just trying to learn, then I apologize if I may seem rude, but your post comes across as just another VB bashing. Might I add the old sh!t heaps on the 737 fleet cannot fly as high as DJ, as they are Australian Airlines relics called B733 and B734:yuk: which cannot fly as high as the NG. The QF NGs as stated above have the same pressurization systems as DJ.

[Dehavillanddriver]

Virgin has the 500 ft per minute rate of climb/descent option as opposed to the 300ft a minute option.

Other than that I believe it to be bog standard.

[Centaurus]

Not trying to rubbish earlier comments but 500 (sea level) feet per minute cabin rate of change can be a bit savage on the ear drums during descent if you have even a slight head cold.

I believe that this figure is generally accepted as the upper range limit when descending non-pressurised types. 300 fpm cabin rate is much kinder on the ears and provoke fewer complaints. With a full aircraft and someone has an ear problem on descent, I doubt that the FA's would be aware of it unless the individual specifically made an issue of it after landing? And with the rushing between flights to change aircraft, would an FA have time or inclination to formally report the problem on paper?

[Capn Bloggs]

Bank Angle 50,
Please calm down. It sounded like and entirely reasonable question to me, and now Dehav says that there may be a difference between DJs and QFs jets.

For the more constrained on this thread, since I don't fly 737s (well some people say I do...), how does the rate thingee work? Is it possible to descent reallt "late" and catch the cabin, or at least "make" the cabin rate increase above the normal amount?

[airsupport]

It may not even be the fault of the Aircraft or Airline.

It MAY be the passengers.

I had exactly the same thing happen to me a few years ago when working Overseas with an A300-600.

I was away from main base for a few days and had a cold/flu that was getting worse by the day, when the time came to return to main base I just wanted to get home, however on that "normal" flight back to New York I had exactly the same thing happen to me, and couldn't fly again for over a month.

It was NOT the fault of the Aircraft, Airline or our Pilots, in hindsight I should not have flown in that condition.

[V1OOPS]

Just a thought - DJ did (and maybe still does) have a run of first time flyers amongst its regular pax. I can imagine them enthusiastically poking fingers in their ears on arrival, popping their ears for the next 3 days, then later telling a quack they've recently been on a sub-orbital ride to Sydney.

If I recall correctly (when not distracted by a straining blouse), DJ's pre-takeoff cabin safety brief says "... the cabin is pressurised for your comfort .... ".

I guess it's worded thus, so those first timers don't get too anxious?

[jindavik]

bankangle50 This was my first posting here. It was not a wind up. It was not an attempt to stick it to V.B Just a legitimate question. You sound a little paranoid.To everyone else thanks.

[Time Bomb Ted]

Could it possibly be that in order to NOT lose money by changing flights, Pax are flying with colds and flu???

TBT

[BankAngle50]

Dehavillanddriver, I have search the manual and cannot find any [OPTION--……….] in Air Systems. I would be interested to know if infact such option exists. When the aircraft descends 0.25psi below the selected FLT ALT, the cabin begins a proportional descent to slightly below the selected LAND ALT. There’s no fixed rate (Feet per min) as such, like on Turbo props. The only option is a High Altitude Landing System, which nobody would buy in Oz.

Normally any option is stated clearly in Vol 2. How would they get around the max diff of 9.1 psi if such an option exists? They would need a much lower Cabin ALT, hence higher diff to use a lower rate during descent. Not possible????

The classics (which fly lower) use a lower differential than the NG. The NG uses 8.35psid above F370, 7.80psid F280-370, and 7.45psi <F280. So perhaps pax notice the lower diff on the classic. :yuk: Its really not that much.
I believe the NG’s are the same, and its just the pax.

Jindavik , you said you had 10000 hrs on jets, hence I thought your question was a joke:ok: .

[Yorik Hunt]

Jindavik, it is possible to tweak the pressurisation in a NG simply by setting a different altitude to that you are cruising at - that simply tricks the auto controller. What cannot be done is change the programmed ROC or ROD, or the maximum differential pressure, and those would be the most likely causes of ear damage.

To summarise that - it is very unlikely that flying with VB contributed to your Docs customers complaints. The pressurisation systems simply don't allow it. Same goes for QF's 737's.

[jindavik]

Thanks Yorik. If for some reason you were held at a high level until close to the field and require a high rate of descent does that mean the controller will exceed 300/500 fpm or you catch the cabin?

[airsupport]

Some people may find this of interest, many others do. :ok:

It is NOT an advertisement, and I have absolutely nothing to do with it. ;)

It is a wealth of info on B737s. :ok:

web site (http://www.b737.org.uk/)

[TIMMEEEE]

Jindavik.
To answer your question the system used in these aircraft are automatic and the cabin differential is programmed to a maximum cabin altitude of about 8000 feet (at max cruise altitude of about FL410 for the 737-800).

If cruising at a lower level the cabin altitude will be lower.

Typically any pain experienced in case of inner ear infections/colds and/or eustachian tube blockages will be more noticeable whilst descending while the gases are trying to escape the body.

The system is programmed for around 300-500 feet per minute on descent which is quite comfy for the pax.

It sounds like the people affected all flew with head colds, inner ear infections or similar.

The B737 is the most popular passenger jet in the world so if this was an endemic problem with VB all pax would complain which they dont.
Coincidence maybe, but whilst pax are warned not to fly with a head cold it is quite obvious alot of pax are either ignorant of the effects of flying as described or ignore warnings.

[A.H.]

I always thought it better to ask a dumb question than make a dumb mistake so, if you are flying at 20k or 30k feet etc what cabin pressure should I be feeling 5000' of 8000' ? Just a dumb question so Props don't get sh!tty just a simple answer will doThanks
A.H.

[Dehavillanddriver]

bankangle50

It is indeed an option out of the standard options catalogue if I am not mistaken.

Not sure if it is a maximum though.

[HotDog]

A.H. roughly speaking, 8,000ft.

[mainwheel]

Jindo,

Have you given any of this feedback to your medico?.

He may become a ppruner.

If so, maybe you could ask him some more specifics on this inner ear bleeding. Which side of the eardrums, flow, other surrouding inflamations etc etc. Just finished a dive course in cairns?

What previous history did these particular patients have of ear problems. Did they also notice a change of taste when vegemite was sold?.

It's interesting that it's been mentioned, but I doubt the aircraft has anything to do with it. Or the operator. Virgin operate B737 aircraft the same as alot of other airlines, they would also be reporting similar problems.

I'm continuously amazed by the misconceptions of the average punter. I had a guy sitting next to me one day tell me that they wind the engines up on turnaround for the next start. He'd seen the fan windmilling and worked it out by himself.

Were any first flyers?

[cunninglinguist]

300fpm with 8000 cabin = 27 minutes to descend cab. to sl, average speed on descent 6 miles a minute= start descent at 160 miles, a little early especially if at FL300:confused:
I thought 500fpm was std

[Capn Bloggs]

Timmee,
Typically any pain experienced in case of inner ear infections/colds and/or eustachian tube blockages will be more noticeable whilst descending while the gases are trying to escape the body.
Not correct. The problem for flyers is that the "gases" ie the increasingly dense atmosphere is trying to get IN, not escape. If the eustachian tube is blocked eg a cold the eardrum collapses inward, causing the pain. When you get the eustachian tube open somehow eg yawn, cough, chew, air is let into the middle ear and and all is equalised.

The system is programmed for around 300-500 feet per minute on descent which is quite comfy for the pax.
I don't know where you get this idea from: 500ft a minute is quite harsh as far as I am concerned. For someone who very rarely flies (like some of these "new" Virgin pax) 500ft per min could be a real problem, and that doesn't mean only if they have a cold. If you asked joe public how they defined a cold, they would probably say in bed on panadol: that's a far cry from what we know can cause big issues with ears in aeroplanes, especially if the standard rate is 500ft per min. A simple runny nose without the correct ear-clearing procedure down the hill will cause problems.

[jindavik]

I have just wrestled the computor off my daughter. I reckon the jury's in. All those punters who caught the greyhound bus are moving on to low cost airlines colds and all. V.B has attracked a lot of new flyers (good on V.B) but there is a whole new bunch of punters that need educating re: flying with head colds. That is what Iwill tell my quack.

[itchybum]

Harden up.......

500 ft/min is nothing outrageous. What did you do in pistons (if you flew them)? You have to come down eventually. And 500 ft/min is what is taught unless things have changed lately. On the winjeel it was 1000 ft/min.

And if you notice discomfort? That's what the valsalva manoeuvre is for.

[cunninglinguist]

By my reckoning Bloggs, if your machine descends the cabin at 300fpm and assuming an 8000' cabin, you would need to descend 27 minutes prior to landing ( into an SL A/D ), even @ average GS 300, that's still 130 odd miles TOD. ( and I happen to know that your machine doesnt have excess diff to play with )

I would have thought that a wee bit too far away when crzing 28000.;)

[Capn Bloggs]

Cunning,
27.5 minutes, because one has to "catch the cabin" at 200ft so that the machine doesn't land pressurised. 130nm is a tad too far away, but that's what you have to do for 300ft/min. We "use" 500ft/min (as you know??!!) so we descend closer in than 130nm. Descent points being too close? Don't get me started!

Itchy,
It may be OK for for ex-RAAFees, but Joe Public wouldn't know what the valsalva manoeuvre was (and neither, possibly, do the "experienced" chooks in the back) so the first thing they know is they have sore ears or worse.
Besides, pax in pistons were probavbly so terrified of what might happen generally they didn't worry about their ears!

737 Drivers,
What does happen to your cabin rate of descent if you descend late? Does it/can it exceed 500fpm or this simply not possible because of descent path/drag issues?

[Hudson]

Itchy Bum. Where on earth did you get that figure of 1000 fpm for a Winjeel? Your instructor must have been pulling your leg...The aircraft was designed for RAAF training including aerobatics. Try diving to get the required speed for a roll-off-the top and you can betcha the rate of climb and descent during that manoeuvre will be way in excess of 1000 ft per minute. If carrying a passenger other than aircrew types, we used good airmanship and tried to keep en-route descent rates to a reasonable figure (3-500 fpm to prevent ear pain.

[itchybum]

Yes I know all that. But as a student at 1FTS we never carried any passengers.

And I didn't realise you'd mistake that quoted RoD as anything other than that... "descent rate". Who looks at VSI during aeros??? I could be wrong, it was a while ago but I seem to recall Performance was gained from a Power plus an Attitude including when diving for speed for a Roll-off-the-Top. Nothing to do with RoD??

I wasn't talking about anything to do with roll-off-the-top, loop, stall-turn or any other aerobatic maneouvres... I never tried anything that fancy when recovering back for a re-join!!!

If you flew the Winjeel "operationally" then you have experience beyond mine and I'll take your word for it the techniques employed were different to the rigid processes at 1FTS.

[Capn Bloggs]

Bloody Queer Eff Eyes...

[Kaptin M]

Vb's Boeing 737 pressurisation system is no different to EVERY other operator of the same equipment - including QANTAS.

Just to clear up a previous Q & A by A.H. and HotDog respectively - the cabin altitude at 20k is MUCH lower than that at 30k, at lower levels the cabin altitude is maintained at sea level (or close to) in the case of Oz & N.Z.
Cabin altitude usually increases with actual aircraft height, and at 20k actual, (without reference to the table) the cabin altitude remains at almost (in the case of Oz & N.Z.) sea level, so there is NO discernible effect.
8,000 feet cabin altitude is the MAXIMUM, and - depending on each individual aircraft types max ceiling (e.g. 37,000' or 45,000') - that will be the max. cabin alt.

From Capn Bloggs, "What does happen to your cabin rate of descent if you descend late? Does it/can it exceed 500fpm or this simply not possible because of descent path/drag issues?"
It is possible for the aircraft to "catch" the cabin with high speed (high actual ROD's), in which case the cabin will descend at the same rate as the aircraft.
However, with the 250 knot below 10,000 restriction, this hardly ever happens.

For people not familiar with the valsalva manoeuvre (holding your nostrils and exhaling against them), drinking, or chewing and swallowing has the same effect. (That's the reason candies/lollies are handed out prior to/during descent, by the F/A's :O ).
Likewise babies crying on descent should be ENCOURAGED by cabin crew, as it gives them relief - better still, try to get Mum to stick the baby on the tit.
Works for me EVERY TIME :ok:

Edit - To clarify, cabin "pressure" changed to cabin "altitude".

[30/30 Green Light]

Kaptin M,I think that your answer wrt AH and Hot Dog is incorrect insofar as the "cabin pressure" at 20k is actually higher than at 30k.The confusion lies in that the "differential" (dependent on system and schedule) may be lower,however the actual cabin pressure will be higher.If we refer to the cabin ROC during climb we will find that it is(normally) indicating an increase in cabin altitude relative to its datum which is its departure field altitude,and will continue to do so until it reaches max diff. When on descent the cabin ROC will indicate a decrease in cabin altitude.I say "normally" above, because if your departure altitude is greater than your destination altitude eg. CBR-SYD,even though you climb out of CBR the pressurisation will descend the cabin to destination through isobaric hold,etc.The confusion arises in that we are actually controlling the rate of "depressurisation" and then limiting it to a maximum differential,and then on descent controlling the rate of pressurisation to return the differential to zero.I remember once being told that "airconditioning is the control of supply of air to the cabin and pressurisation is the control of exhaust of the supplied air" or words to that effect.

Cheers