Swiss A320 cabin pressure, "ATC refused descent request"

[Cyrano]

According to this report (http://www.aerotelegraph.com/swiss-airbus-a320-zuerich-valencia-notfall-druckkabine) (in German), an LX A320 had cabin pressure problems en route ZRH-VLC last Thursday 12 Sept. It's reported that the crew requested a lower altitude but ATC would not grant this, even after a Pan call, until finally the crew called Mayday.

Assuming the report is accurate, does this just illustrate the lack of consistency with which Pan calls are treated? Should the crew have called Mayday immediately? Or could ATC have been more responsive even in the absence of declared urgency/distress?

Google translate link here (http://translate.google.com/translate?sl=auto&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.aerotelegraph.com%2Fswiss-airbus-a320-zuerich-valencia-notfall-druckkabine).

[Cmon-PullUP]

If you have pressure problems en-route it should be a Mayday with immediate descent, and once safe you can downgrade again to a Pan or cancel it altogether depending on your situation.

A request or a Pan does not require ATC to give you preference because you are not in danger - if you were you would call mayday!! A Pan means they should give you preference when circumstance allows for it, and if they don't you must wait. In Europe the airspace can be very busy, so they might not have been able to give a descent without moving everyone else away, just because of a polite request.

It is really about the crew determining how much hurry they are in, and classify it accordingly. There is no room for politeness when the :mad: hits the fan.

[CaptainProp]

Did not read the details on this one yet, but I'm with PullUp on this one. If you have pressurisation issues and need to descend then you make a mayday call.

[dcvr]

Agree with PullUp too. It could be lost in translation but there's a big difference between "request lower altitude" and "require lower altitude" (pointed out by a controller to me on a recent tour of YMML en-route ATC).

[single chime]

"Require" is not a ICAO recognized term. It is widely used in Oz and NZ (I believe they have a requirement (pun!) in their AIPs to use "require" to request WX deviation). But it is still non-standard R/T in the rest of the world.

[latetonite]

Maybe just over Mont Blanc when the guy was so gentle to request..

[McBruce]

Depends on the situation and experience of the crew/controller. Remember one situation when we departed a small German airport in Class G airspace. Stopped at FL80 and TCAS showed a conflict straight ahead climbing 500ft below. We requested climb to be denied due to military airpsace above. Neither left or right would be given as well. TCAS RA Climb. Controller probably had a lot more explaining and paper work to do after that one!

[Dufo]

One day, long time ago, I was told that in critical situations you should do such stupid things which would enable to write the report afterwards.
Meaning to live to tell :E

[ATC Watcher]

Read the article, it misses something and without a transcript of the R/T and a traffic situation it is difficult to assess who is miunderstanding who.
If a "request" is made and you have traffic below or opposite , or an active military area below, any controller is not going to give an authorisation to descend.
Pan-Pan calls are not giving any priority., nor require special assistance . read ICAO phraseo definitions.
Mayday calls + 7700 will
I understand from the article that once the crew did that he could go down.

I would have thought that after many incidents and even accidents ( Avianca comes of course to mind) the declalring emergency R/T procedure had been tightened up. obviously not.

[NuGuy]

ATC does not fly the airplane. The pilot does. You fly the airplane by grabbing the yoke (or stick), not pressing the PTT button.

You TELL ATC what you ARE doing, and they get to facilitate it.

Pilot IN COMMAND.

Learn it, love it, live it. Button mashers need not apply.

[ATC Watcher]

You TELL ATC what you ARE doing, and they get to facilitate it.
You are absolutely correct , in class E,F and G airspace, or when following a TCAS RA or when declaring emergency and/or squawking 7700.

For the rest of the time , if you want to come to control aispace you are subject to ATC instructions. I you do not like it, perfectly OK, just stay out of Control aispace and stay VMC .
I am not having an argument, just stating the basic facts of Air navigation today..

[Juan Tugoh]

For the rest of the time , if you want to come to control aispace you are subject to ATC instructions. I you do not like it, perfectly OK, just stay out of Control aispace and stay VMC .

Except that I will not fly through a CB because ATC will not let me deviate, or because the frequency is too congested to get a call in early enough, or the controller is French or Spanish and too busy chatting in their own language. Yes we are subject to ATC instructions but that does not mean to the detriment of the safety of our passengers.

[Hotel Charlie]

ATC Watcher: For the rest of the time , if you want to come to control aispace you are subject to ATC instructions. I you do not like it, perfectly OK, just stay out of Control aispace and stay VMC .
I am not having an argument, just stating the basic facts of Air navigation today..

I think you might have to reconsider ..... You do NOT steer the airplane as little as a traffic cop steers YOUR car! You are, and should remember you are a service provider and I respect you guys for the mostly excellent job you do.
I tend to think that those of you who do know who is in charge are also the ones that really run an efficient airspace! :ok:

[lomapaseo]

above

ATC Watcher:
Quote:
For the rest of the time , if you want to come to control aispace you are subject to ATC instructions. I you do not like it, perfectly OK, just stay out of Control aispace and stay VMC .
I am not having an argument, just stating the basic facts of Air navigation today..
I think you might have to reconsider ..... You do NOT steer the airplane as little as a traffic cop steers YOUR car! You are, and should remember you are a service provider and I respect you guys for the mostly excellent job you do.
I tend to think that those of you who do know who is in charge are also the ones that really run an efficient airspace! http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif

I'm happy to see the polite discussion above. However, the declaratory statements do need to be sorted out among us (sic)

are there any published instructions that might help clarify this ?

[Willit Run]

After few tequila's, and little experience;

A few years ago when I was an engineer on an A-300, Some how, unbeknownst to me, the pacs never got turned on, or, some how got turned off, but at FL300, we got an altitude warning horn. WOW! anyway, before declaring an emergency(mayday) or even a WTF Pan Pan, ole numbskull done figured it out, and with out any rubber jungle, all was well.

Not all pressurization issues are a Mayday!

Let the fodder fly!

[Check Airman]

On this side of the pond, an urgent call will certainly get you whatever priority you need. If we're experiencing unusual ops, I usually have to insist to the controller that no assistance is required, as they are (thankfully) extremely eager to get people out of our way.

[Offchocks]

I will probably get shot down for this, but I would initiate a turn off the airway whilst starting the descent, then I would transmit a Mayday.

[stilton]

Absolutely what I would do, there's no debate about it , that's how our checklist is written and has been on every Jet I have flown :ok:

[Denti]

Which is about right anywhere except europe. Not to mention that nobody (except over spain) flies on an airway to begin with, if you turn off one you are smack right on about five others as they are so closely knit.

We asked eurocontrol as well as the ATC service providers of the major european countries and they all advised us to just descent on planned routing (usually a direct to some point), uncoordinated turns would increase risk and ATC workload.

[ironbutt57]

The report on Av Herald sheds some light...good grief folks...fly first sort out the crap later..how many precious minutes were wasted on trying to get a "clearance" commanders emergency allows deviation from any clearance as necessary to meet the needs of an emergency...

[Lord Spandex Masher]

For the rest of the time , if you want to come to control aispace you are subject to ATC instructions. I you do not like it, perfectly OK, just stay out of Control aispace and stay VMC .
I am not having an argument, just stating the basic facts of Air navigation today..

Actually I think ATC requests are subject to the commanders agreement.

[LLuCCiFeR]

After few tequila's, and little experience;

A few years ago when I was an engineer on an A-300, Some how, unbeknownst to me, the pacs never got turned on, or, some how got turned off, but at FL300, we got an altitude warning horn. WOW! anyway, before declaring an emergency(mayday) or even a WTF Pan Pan, ole numbskull done figured it out, and with out any rubber jungle, all was well.

Not all pressurization issues are a Mayday!

Let the fodder fly! Just about the only sensible answer on this thread.

I admit that I don't know all the details but they reported a pressurization problem not a rapid decompression, so why all children of the magenta line would declare a mayday and immediately start an (emergency?) descent is beyond me.

A pressurization problem (perhaps just an abnormal cabin climb rate, or a spike) could be as simple as selecting another pack controller or selecting the outflow valves to manual. However, once a full (emergency) descent has been initiated you're more or less committed to divert as well, because you you probably won't have the fuel to climb back to a normal cruise level once/if the problem is solved.

Obviously thinking and problem solving is not part of a pilot's job these days...

[Groundloop]

how many precious minutes were wasted on trying to get a "clearance" commanders emergency allows deviation from any clearance as necessary to meet the needs of an emergency...

Well, if it was an "emergency" they should have declared a Mayday immediately.

[PENKO]

ATC-watcher, in the end, the pilot is on top of the food chain. Not ATC. If the pilot thinks he must descend, he will. With or without a mayday. Within or outside of controlled airspace.

Now the paperwork afterwards might be interesting if the pilot violated his 'privileges', but please don't forget it is the pilot that is served by ATC and not the other way around!

[Avman]

but please don't forget it is the pilot that is served by ATC and not the other way around!

Of course ATC is a service provider, but whilst a pilot is legally responsible for himself, his crew, his passengers and his aircraft, I wouldn't belittle the fact that a controller is legally responsible for hundreds of aircraft, their crews, their passengers etc., each and every duty day.

[ATC Watcher]

PENKO and a few others:
Far from me to dispute the fact that ATC is there for the pilots, not the other way around. I am a pilot too, and today I fly far more than I control ( I stopped handling an ATC mike 8 years ago ). And when I fly I want ATC to help me without arguing too.(they mostly do, no worries :E )

Let's get away from Ego's for a second . and look at safety : back to the original thread.
Basics: If a pilot a has a serious problem that do need immediate attention and priority, emergency descend , whatever, : he should declare emergency and call Mayday , squawk 77, whatever and he will get the full support of everyone.
Pan-Pan will not get you anything basically.It just information that there is a problem on board nothing more.
And that was the original point here I beleive.
Telling the problem in long plain language will not help much neither. We need to use Mayday . and/or 7700 . period. Remember Avianca .

Some children of the magenta line ( but not only them I would dare to say reading some posts ) not born when Avianca crashed and not understanding this should perhaps refresh themselves by reading this excellent booklet last 2 pages :
http://www.skybrary.aero/bookshelf/books/115.pdf

As to descending straight ahead without telling anybody , or when it is over ( been there, got the T-shirt) while I can understand that as a pilot ( Aviate, navigate ,communicate, : yes comm is last, I know that ) I do not like it as a controller, because I am responsible to keep everyone clear of each other. But I know I have to live with that.

Doing an emergency descent staying straight on the airway axis ?
Use common sense and knowledge. turning 30 degrees will definitively help. ( (unless you are above FFM, SPI, DIK, SPR ,TRA, etc.. of course but you can't win all the time. Need a bit of luck too. But staight ahead under RNP5 /GNSS NAV ? No way for me.
Remember also TCAS is extremely bad or will even be inhibited with very high rates of descent.

Now some inside ATC info :
Modern ATC systems takes up to 10 seconds to display ALT and if it is from level flight to 4-5000 ft lower in one go, most systems ( mine did) will not display altitude asuming garbling .(at least for one update),
Then ATC might not notice , if you are cruising level flight not directly confilcting with anyone his attention/focus will definitively not be on you.

The airspace is such structured that the sectors ( read altitudes) below are not controlled from the same room or even the same country. Military will only clear the way below you if they see 7700 . They do not normally monitor civil a/c altitudes deviations.
So keep communicated until the end when doing an emergency descent ,and you're on your own relying on luck not to meet someone on your way down. Tell ATC a.s.a.p and you'll increase your chances someone will get them out of the way. Nothing more to it.

[RAT 5]

ATC Watcher: Many thanks for some of your comments regarding pilot actions and emergency descents. There was a discussion topic some weeks ago. Many different opinions about when to inform ATC of your E.D. before executing it or before; TA only on TCAS; turning L or R etc. Sadly little ATC input came into that topic, but now you have expressed your thoughts. We wonder if ATC has an SOP for E.D's as do the pilots? Trouble is there did not seem to be a standard SOP amongst the airlines. I hear ICAO is looking into it. About time.

[ATC Watcher]

RAT 5 : thanks. I was not aware of a previous discussion on E.D.pity. lots to talk about.
To answer your question about ATC SOPs for ED, well it is exactly like with airlines and air aircraft operators; everyone has its own idea and train its staff accordingly.
Also, the chances for a controller to actually excperience an E.D. in his shift is rather rare. so easily forgotten,.
Some ATS untis/service providers train their staff better than others and even provide emergency chekclists. But not everyone.

Interestingly the military ATC do use emergency check lists , and when the German DFS took over their military they discovered the benefits of controller check lists and introduced them for civil controllers. A very good initiative, but far from being standardised elsewhere unfortunately.

As to ICAO, well it moves slowly ,some men representing some Sates still live in the B707/VC10 era. A bit like here on this forum basically :E

[West Coast]

ATC watcher

I accept most of what you say, just as you must accept that at times the PIC may have to act unilaterally and advise ATC later. A high alt wake encounter (FL390, 747 being the generator) to the shaker required an immediate response on my part before ATC could be advised.

[Ian W]

ATC watcher

I accept most of what you say, just as you must accept that at times the PIC may have to act unilaterally and advise ATC later. A high alt wake encounter (FL390, 747 being the generator) to the shaker required an immediate response on my part before ATC could be advised.

I was a centre 'emergency' controller where we had an 'distress/diversion cell' that took executive authority over all emergencies in the FIR/UIR.

All any aircraft needs to do is set 7700 or call "MAYDAY MAYDAY MAYDAY callsign WAIT OUT". Something that PNF could do perhaps but it would ensure that the control facilities affected by your flight would immediately start vectoring other aircraft away and stop handoffs to the sector you were flying in and moving aircraft off the frequency you are on.

Then from observing what your aircraft was doing other alerts and administrative actions can be taken such as identifying and alerting nearest suitable airports etc. all this without you saying anything more. However, if you do NOT tell ATC that you have a problem, what you will get is continual annoyed calls over RT from the controller (and possibly repeats from 'helpful' other aircraft in the sector) until the controller decides that you might be in emergency or more probably these days that you may have been hijacked.

I would suggest it makes everything a lot easier and safer to alert ATC with a truncated Mayday call, then tell them to wait. When you have time you can tell ATC what you need and everyone will have already been cleared out of your way.

[West Coast]

Ian

If time permits yes.

The correct immediate response is to aviate however. The other guy is ensuring I use the correct procedures before he/she does anything else. Shortly, hopefully very shortly thereafter ATC will be advised. What if the frequency is saturated and it takes a number of seconds to change the squawk and have it recognized by ATC and hope they have an open frequency to move any conflicting traffic? Surely you don't expect me to counter the aerodynamic laws that are taking effect if I don't fix the problem. What of a single pilot ship such as a citation? Should that pilot put off the ingrained stall recovery procedure to talk on the radios to inform ATC before recovering from a stall? No, aviate, navigate then communicate. Immediate responses are trained for a reason.

Sometimes you have to act and understand that there's no guarantees in life. Hopefully the big sky, little airplane theory works in everyone's favor. In my situation, had I waited till ATC responded and moved airplanes if there was a confliction, I would have been headed downhill anyway, in a stall however.

Literally sometimes all you have a 2-3 seconds to react. Only once in my career so far have I had to do something like that. Given the few years it took off my life, hopefully the last as well.

You can argue it all you want, but that's what going to happen. If its any consolation, I agree with what you've said for almost all situations.

[DozyWannabe]

I would suggest it makes everything a lot easier and safer to alert ATC with a truncated Mayday call, then tell them to wait.

Of course, there are extreme circumstances where even that is practically impossible - I'm thinking BA5390/G-BJRT.

That said, the F/O in that case did manage to get a Mayday out after the emergency descent.

[bubbers44]

Depressurization can be explosive or just a control problem. Each is handled differently. After immediate action use check list. If a control problem just use checklist.

[zonoma]

LSM et al, the UK AIP ENR section can be found here (http://www.nats-uk.ead-it.com/public/index.php%3Foption=com_content&task=blogcategory&id=4&Itemid=11.html) and section ENR 1.4 ATS Airspace Classification states ATC instructions are mandatory for any IFR aircraft flying in Classes A to F airspace, and any VFR aircraft flying in Class B or C airspace.

NATS train their controllers to expect everything and anything, and during the emergency simulations for training, sometimes there are examples of emergency descents with no communication and turns. It is well known that no communication is likely in the early stages, all a controller can do is the best they think at the time. If this is expected, then anything else is a bonus, and for me, the biggest bonus would be to squawk 7700. This one thing simply draws the attention of not only the controller working the aircraft, but every other controller with airspace in the vicinity or controllers who are authorised to penetrate CAS without coordination (military etc). As for the turns, they aren't liked in NATSland, but again training covers this. My advice is to be very cautious turning if you have already been assigned a vector, it probably means there is another one not that far away that you might just turn into.

[calypso]

If I am on a vector I assume it is because there is a conflict at my level, not many thousands of feet below during my ED. Clearly this is a case of turn AND descent, so the chances of hitting someone at my level are pretty slim. In any case I don't imagine many people would turn if they are off the airway on a heading.

If I am on an airway on the other hand I would turn as it is not at all uncommon to see aircraft exactly below me.

[ATC Watcher]

West Coast :
Nobody ( I think) is suggesting than faced with an Emergency descent you should first contact ATC and request ATC instructions !
What I ,and others here ,are saying is that, in order to be the safest ( which we all strive for )when faced with an emergency descent , call Maday and turn 7700 as soon as you can. No pan-Pan, no long stories, and not wait until things are over.
Yes, the big blue sky works most of the time , but in a complex and congested airspace luck will run out one day.
So why not increase your chances to have a fee path below to descent into ?

We pilots and controllers are normally very good at multitasking. (The women among us even better :E ) Why not ,WHILE AVIATING , pressing the PTT and saying something like : Company (*) Mayday-Mayday Emergency descent "

Training for this in the Sim , so that it becomes a reflex will help.

Then training controllers how to reply in a consistant manner ( i.e everybody everywhere knows how to react) will also help.

(*) experience shows that in many emergencies pilots under stress get the trip number wrong. not an issue if pilot( or someone else in the cockpit) squawk 7700 )

[West Coast]

Yeah, sorta of.

Aviate comes first, not concurrently with communicate.

[zonoma]

If I am on a vector I assume it is because there is a conflict at my level, not many thousands of feet below during my ED.
NEVER assume! It could simply be a vector for another aircraft to descend through your level and could already be below you, and only 5nm away, possibly even just 3.

[Hotel Tango]

Assuming something is the first step towards a possible catastrophe!

[calypso]

Rubbish. Assumptions permeate everything we do in aviation. Every performance calculation and every SOP is based on certain assumptions.

If I need to descent right now! I need to do so based on a number of assumptions as I do not have enough time or enough information to do a full analysis of all the factors at play. One of those is that if I am on the airway someone might be directly below me. By and large if someone is going through my level 5 miles or less from me I do know about it if they have a transponder. It is my job to know and be aware. If I don't happen to know about the other traffic either turning or continuing straight ahead might result in TCAS as I start the ED maneuver. Since I do not which I just have to take my chances and follow our SOP which requires a turn (based on a number of assumptions of course...)

[Hotel Tango]

No, not rubbish at all. I don't disagree with your reasoning but I stick to my statement.

[ATC Watcher]

Calypso :
Assumptions permeate everything we do in aviation
Not in Aviation as a generic term . In Flight testing maybe, . In ATC assuming things nearly always lead to errors and incidents. We are trained never to assume. That is what HT was saying I think.

And a word of caution in your reasoning , ( not bad per se ) If you plan to use TCAS display to separate yourself to start and during an ED , you're in for big surprises. I would not do that. But a turn, even a slight one to get away from Navigation accurracy, absolutely !

West Coast :
Aviate comes first, not concurrently with communicate.
Then we can assume you definitively not a woman :E

[West Coast]

Assumptions do factor in. Especially as Calypso noted, in the area of performance. ATC watcher, as you're a pilot (my assumption being of a large turbine powered acft) is your performance for each takeoff predicated off the assumption an engine will fail? I know mine is.

[ATC Watcher]

West Coast : I see what you are saying , we just have a different definition of the same word. The "asumptions" you mean are taking things into account. Yes as a Pilot I do those of course all the time.

In ATC "assuming" means that you " think" that it is or will be OK without checking.
Like say, issuing an instruction and not receiving an immediate read back : Assuming it is received and will be complied with is the kind of assumpions we are trained fromn childbirth to avoid.
Another typical assumption is expecting an aircraft to behave like 100 others did before in a similar situation . Therefore we do repeat the same instructions over and over again.
One of our training motto is :" in case of doubt, double check, never asume "

The 2 worlds are different.

[West Coast]

Ok, agree with to terms. As to the second para, immediate responses are based on the assumption that the probability of hitting something below my level has a lessor probability than the danger of staying at altitude if that's even a possibility.

[Hotel Tango]

is your performance for each takeoff predicated off the assumption an engine will fail? I know mine is.

Sorry, but I have to be pedantic here. ;) I would suggest that you wouldn't assume an engine failure but that performance for take-off would be predicted in the eventuality of an engine failure. A little like the erroneous term used in American elevators, "In case of fire" instead of "in the event of fire".

[Navcant]

So far the discussion has centered around two players in the scenario. The pilot (aircraft) with the pressurization issue and the controller.

What about the other aircraft in the immediate vicinity that could be catastrophically affected by a pilot who descends first and advises ATC later? Is TCAS going to save you from a collision? Likely, but what if you're a heavy jet and your descent/ deviation has put another aircraft right into your wake?

Things to consider....

[West Coast]

No guarantees in life. That heavy is going to do the same if his ship is the one in jeopardy.

[DozyWannabe]

Depressurization can be explosive or just a control problem.

To be fair, BA5390 was a bit more than a depressurisation issue - the windscreen blew out. This led to a specific problem regarding communication with ATC as the wind noise rushing through the flight deck prevented the F/O from being able to hear ATC's transmissions, and he had no way of telling whether ATC could hear him. Added to that, his emergency descent flightpath was going to take him through the feeder zones for London Approach.

Of course, all this is before you take into account that just to his left, the Captain had been sucked through the windscreen aperture, held in only by - intially - his toes caught in the ramshorn yoke, then by two cabin crew who held on to him for dear life throughout the rest of the sequence.

Hence my reference to it as an extreme example! That he managed to get a Mayday out after levelling out post ED shows professionalism and a presence of mind that many can but aspire to.

[stucano]

Interesting / worrying that the advice given to Denti by eurocontrol seems to contradict ICAO Docs procedures (cut and past below from UK AIC) which are also supposed to be ignored when flying in UK airspace.

God forbid we get any joined up thining on something so fundamentally serious :ugh:

Then we have those that will blindly follow SOP regardless of rules or what is sensible.

Whatever happened to airmanship. Aviate (initiate the descent), Navigate (look out and don't hit anyone), communicate (7700 & get on that radio ASAP).
Turn or not as the case may be, that really depends on the factors of the day and your level of SA and knowledge of what / who is around you.

The last sentance below says it all!!

2 ICAO Procedure
2.1 Procedures for pilots upon hearing an emergency descent broadcast are published in ICAO Doc. 4444 (PANS-ATM) paragraph
15.1.4. More recently, ICAO have published detailed procedures in Doc. 7030/EUR - Regional Supplementary Procedures paragraph 9.1
for pilots experiencing an emergency descent in the European Region. The Regional Supplementary Procedures are reproduced in
paragraph 2.2 below.
2.2 Doc. 7030/EUR states that, when an aircraft receiving an ATC service experiences sudden decompression or a malfunction requiring
an emergency descent, the aircraft shall, if able:
a. Initiate a turn away from the assigned route or track before commencing the emergency descent;
b. advise the appropriate air traffic control unit as soon as possible of the emergency descent;
c. set transponder to Code 7700 and select the Emergency Mode on the automatic dependent surveillance/controller-pilot data link
communications (ADS/CPDLC) system, if applicable;
d. turn on aircraft exterior lights;
e. watch for conflicting traffic both visually and by reference to ACAS (if equipped); and
f. co-ordinate its further intentions with the appropriate ATC unit.
2.3 The aircraft should not descend below 10000 ft amsl, or Minimum Safe Altitude, whichever is the higher.
2.4 Turning-off or Remaining on Track in UK Controlled Airspace
2.4.1 UK Controlled Airspace is complex and congested; traffic is often oriented on the airway in certain directions or flows. Therefore, if
able, pilots should remain on the assigned route or track whilst carrying out the emergency descent; unless to do so otherwise would
endanger the aircraft. Notification of this preferred action in UK Controlled Airspace shall be published in the UK AIP GEN section under
PANS-ATM paragraph 15.1.4 - Emergency Descent.
2.4.2 If a turn away from an assigned route or track is initiated, pilots should note that they may not be aware of traffic in their proximity
(especially if flying on an assigned heading): nor of aircraft below them, not on the selected frequency, in adjacent airspace sectors. However,
it is ultimately the pilot’s responsibility to take the action most appropriate in the circumstances.

[ettore]

After reading all the wisdom spent by well educated professional pilots on this thread, may I - as a Swiss citizen - suggest (and risk) a reasonable guess ? The Swiss PIC did not have the guts to call straight away a mayday, then let his buddy on the right seat do the check-list and eventually correct his assessment of the situation.
To me, this wouldn't be an unusual cultural trait. Nothing to do with ATC, but with a typical Swiss behaviour : do not alarm the neighbourhood as long as fire is not burning your pants.
End of the story ? ;)

[bubbers44]

I lost auto pressurization one day in a B737, switched to standby and that didn't work so went to manual and was able to maintain pressurization. We also previously had lost the autopilot so were hand flying so when they told us to hold going into SFO from SEA told them we kind of had our hands full and holding was not a good idea so they gave us a break and let us continue our descent for landing. No need for an emergency descent in our case but we were busier than a one armed paper hanger.

[blind pew]

Ettore
Seen it many times myself...well stated.
The Swiss military culture.

[Lord Spandex Masher]

LSM et al, the UK AIP ENR section can be found here (http://www.nats-uk.ead-it.com/public/index.php%3Foption=com_content&task=blogcategory&id=4&Itemid=11.html) and section ENR 1.4 ATS Airspace Classification states ATC instructions are mandatory for any IFR aircraft flying in Classes A to F airspace, and any VFR aircraft flying in Class B or C airspace.

Until they conflict with what I want to do to ensure the survival of yours truly, and then you get a good ignoring. :ok:

[BOAC]

Not sure we can lay this completely at the Swiss 'national psyche' door. It does seem that there was insufficient 'urgency' in the initial call and the 'reaction' to PAN PAN PAN is well known. I do not see anywhere what the problem was, and it appears it was not 'dramatic' enough to drop the pax masks. In any case, our checklists do imply we should try and 'solve' such a pressurisation problem at cruise level before screaming earthwards.

[BARKINGMAD]

Is there anyone in the aeromedical profession prepared to state how long a descent from the '40s can be delayed, if at all, with pax and crew breathing from their certificated O2 supplies, before the danger level to all increases to the stage at which it outweighs the risk of screaming earthwards, either on track as per one procedure, or turning off onto an unpredictable track as per other rules?

The skies are now so congested and LNAV so stunningly accurate, that the former on track procedure has obvious multiple targets as has the dive right/left option and the risk of losing MORE than one aircraft vastly increases.

Hell will freeze over or such a mid-air will occur, before ICAO will get around to standardising the action.

Meantime I simply ask the question, can we wait the (hopefully) short time at altitude whilst the team with the BIG picture, ATC, sorts out a suitable escape track.

I appreciate there are parts of the world where this can be accomplished better and quicker than others, but the I query the gutbusting rush which characterises the sim training for these events.

And this question is posed by an aged ex-mil poster who has done both the hypoxia and explosive decompression training in the chamber, but luckily not experienced the same in a shiny people moving tube.

I am NOT querying the necessity to aviate, navigate etc, but I am posing the subsequent decision to point the plane rapidly into almost certain danger, instead of waiting briefly for a more considered and informed option?

I now don my hard hat and await incoming fire! :confused:

[BOAC]

Hi Barker - I reckon for flt crew on 100% you would have a reasonable time to make a considered judgement 'in the ??40's'??, BUT remember there are significant medical implications for the pax and c/crew with the total hypoxia time which could then ensue.

[10W]

Aviate is the key. The pilot must take action quickly to ensure the safety of his aircraft. Part of aviating is collision avoidance, so if you turn off track where national procedures suggest you don't, then you need to bear in mind that your aviating might be taking you quickly in to a previously separated opposite direction flow of traffic, or in many parts of the UK very quickly in to military danger areas where your TCAS won't show up the ordnance flying around. As with any clearance deviation, responsibility for separation moves entirely to the pilot until he communicates with ATC and an alternative is issued. How good is your situational awareness of what the airspace is either side of track and what you might encounter if you come off track ?

[BARKINGMAD]

"there are significant medical implications for the pax and c/crew with the total hypoxia time which could then ensue"

Agreed BOAC, which raises the question, for how long will the Chemgens supplying CC and pax keep them clear of significant and potentially damaging effects on CC mental impairment and pax discomfort?

All I'm asking is for a short "breathing space", pardon the pun, before the flight deck feel the need to dive into mid-air collision territory.

Have the aircraft makers got some sort of specification as to how well-protected CC and pax are at 41,000ft in the "NG" for example on their airmix masks?

Obviously the pilots are well catered for with 100% and emerg if selected, and they should therefore be able to operate without handicap (apart from that awful inhalation noise, which should have been engineered out BEFORE certification!) and it is this opportunity to think and communicate and then make the best decision for a downwards trajectory which I am asking to be considered.

My Noddy's Guide to the NG states the chem O2 is good for approx 12 minutes of flow, so that ensures some time to take to arrive below 15,000ft which I recall was considered a lesser hazard altitude for humans. However we have no information as to the protection offered at ceiling, and have to presume if it's good enough for CC to operate "monkey swinging" up and down the cabin, then it must be adequate for the purpose, short term?

[West Coast]

It's not always decompression. I got nailed by wake from an opposite direction 747 as I was leveling out at high altitude soon after the RVSM was implemented in the US. Shaker with a wing drop. There was no time to pause for another option.

[BOAC]

It is worth remembering it is a very big sky and a relatively small aircraft, so while you may create excitement if you do 'plunge' down unannounced, you are very unlikely to actually hit anything, and if you gotta go........................

Barker - remember we are looking at less than 20 seconds of 'useful consciousness' at those heights, and there will almost certainly be pax who have not masked up in that time. Also the effect of a 'rapid' will empty the lungs of most of the existing oxy, and the feed from the mask is going to be well diluted at that height plus the lack of a real positive pressure which as you will remember from the Ruddles-drinking course degrades the effect of oxygen - as you say we have no information as to how effective it is. Your 'monkey-swinging' crew could well be stacked in a heap in the forward galley, of course, if they risk moving around at the start:)

[West Coast]

Exactly BOAC. In my case had I waited, I would have been doing the high dive either way, just in a stall potentially.

[Bengerman]

So here we are at 39000' and the ever vigilant FO brings to your attention the cabin vsi. The cabin alt is just over 8000' but has a roc of 200'/min, the outflow valve appears more open than normal, checklists are followed with no appreciable effect so that, after 5 minutes, the cabin is now at 9000'. You have no choice, you have to descend, but you DO NOT yet have an emergency.

Asking ATC for descent since you have a pressurisation issue is the sensible thing to do, it would be foolish to get into the more marginal procedure of an emergency descent if there is no need to. Why wait for the inevitable and place oneself in the more dangerous situation simply to satisfy ATC.

As has been previously stated, the commander of the aircraft can override ANY ATC instruction if he believes that instruction compromises the safety of his aircraft, common sense please, if a pilot states that he has a pressurisation problem why compound that problem by forcing him to declare a MAYDAY?