No O2
Thread Starter
Joined: Nov 2005
Posts: 87
Likes: 0
From: Canada
No O2
Had this question in my first interview and did not think I handled it right:
If your flying say from NY to London and noticed in cruise you had lost all your O2 but your pressurization was good what would you do. I, having never flown anything that could fly from NY to London, said that I would go down to 10,000ft and fly to my nearest airport at that altitude. The interviewer told me that was really low for an airliner what about the fuel. We talked about it for a bit then moved on. I think I was right with 10,000 ft but not sure. Please help.
If your flying say from NY to London and noticed in cruise you had lost all your O2 but your pressurization was good what would you do. I, having never flown anything that could fly from NY to London, said that I would go down to 10,000ft and fly to my nearest airport at that altitude. The interviewer told me that was really low for an airliner what about the fuel. We talked about it for a bit then moved on. I think I was right with 10,000 ft but not sure. Please help.
Joined: Nov 2004
Posts: 1,324
Likes: 156
From: Here, there, and everywhere
10,000 does seem very low. Definitely not any lower than will allow you to get to your nearest suitable airport with reserve if you have decided that you will divert there. Remember, in the very unlikey event that you depressurize at 14,000 or some higher altitude, you can get down to 10,000 very quickly.
Some operators in the event of a depressurization will descend to 14,000 initially, set long range cruise and then when confident that a destination can be made at 10,000, will descend to that altitude.
Some operators in the event of a depressurization will descend to 14,000 initially, set long range cruise and then when confident that a destination can be made at 10,000, will descend to that altitude.
Joined: May 2000
Posts: 3,204
Likes: 2
From: Seattle
A lot depends on the type of airplane, redundancy of systems, and the emergency procedures section of the specific Flight Handbook. A look at the MEL/DDPG would give some guidance, but would not likely be deterministic once airborne.
That said, I would likely continue if the airplane was otherwise unencumbered with related deferred maintenance items (e.g., 1 pack already failed) and there was no specific requirements for immediate landing in the non-normal checklist.
"No O2" in this case merely means the pilots' emergency O2 bottles have been depleted. There will still be O2 for the pax, because they are on separate systems. There is also significant O2 available in walkaround bottles and (possibly) in emergency medical O2 bottles. I would ensure there was an adequate number of these installed in the cockpit or brought to the cockpit in case of a fire or depressurization. AFTER that, a call to Dispatch to ask what else they wanted me to do, assuming I was still prior to ETP.
Descending to 10,000' when cabin pressurization is functional is NOT a good idea...
That said, I would likely continue if the airplane was otherwise unencumbered with related deferred maintenance items (e.g., 1 pack already failed) and there was no specific requirements for immediate landing in the non-normal checklist.
"No O2" in this case merely means the pilots' emergency O2 bottles have been depleted. There will still be O2 for the pax, because they are on separate systems. There is also significant O2 available in walkaround bottles and (possibly) in emergency medical O2 bottles. I would ensure there was an adequate number of these installed in the cockpit or brought to the cockpit in case of a fire or depressurization. AFTER that, a call to Dispatch to ask what else they wanted me to do, assuming I was still prior to ETP.
Descending to 10,000' when cabin pressurization is functional is NOT a good idea...
Joined: Dec 2005
Posts: 33
Likes: 0
From: Middle Kingdom
.....O2 systems (Crew) are not only for pressurization problems. Any hint of smoke in the cockpit will require me and my crew to don O2 masks. Many quick donning masks in use today, require O2 pressure in order to be deployed effectively.
I would certainly make a possible "smoke event", a major part of the decision to whether continue or land at the nearest suitable airport
Cheers
I would certainly make a possible "smoke event", a major part of the decision to whether continue or land at the nearest suitable airport
Cheers
Joined: Apr 2007
Posts: 118
Likes: 0
From: us
hi,
i was under the imression that if your O2 goes down you can get two portable oxygen tanks from the cabin and keep it in the cockpit.
hence you dont have to descend.
and in an emergency these portable tanks have high pressure available.
on some routes descending to 10,000 will be really low.
pls advice me of your views.
thanks.
i was under the imression that if your O2 goes down you can get two portable oxygen tanks from the cabin and keep it in the cockpit.
hence you dont have to descend.
and in an emergency these portable tanks have high pressure available.
on some routes descending to 10,000 will be really low.
pls advice me of your views.
thanks.
Fleet Manager
Joined: Apr 2001
Aviation Qualifications: ATPL
Posts: 7,447
Likes: 310
From: various places .....
A few considerations to take into account (and there are probably others one could dream up) ..
(a) depressurisation - without dropdown masks (and no oxygen gives the same result) the normal certification limit is FL250 and, if the memory serves, a maximum 4 minutes to get down to 10,000ft.
(b) base MEL consideration would consider continuing at cruise
(c) smoke and fire drills are a definite consideration
Perhaps they might have been after an answer along the lines of ..
(a) if fuel critical, stay high on a risk management consideration
(b) otherwise descend to FL250 and continue
(c) consider diverting to nearest alternate due loss of crew smoke protection but balance an assessment of relative risks overall
(a) depressurisation - without dropdown masks (and no oxygen gives the same result) the normal certification limit is FL250 and, if the memory serves, a maximum 4 minutes to get down to 10,000ft.
(b) base MEL consideration would consider continuing at cruise
(c) smoke and fire drills are a definite consideration
Perhaps they might have been after an answer along the lines of ..
(a) if fuel critical, stay high on a risk management consideration
(b) otherwise descend to FL250 and continue
(c) consider diverting to nearest alternate due loss of crew smoke protection but balance an assessment of relative risks overall
Joined: Dec 2006
Posts: 185
Likes: 0
From: N33 24.7 E36 30.8 E 36 30.8
hi
what intruder said makes sense..but what i would like an opinion about is..
even with portable o2 bottles i would worry that in the event of rapid depressurization i would also need the microphone for crew communications..which is not available on the portable o2 bottles..same goes for an in flight smoke event..the crew cannot communicate effectively
what intruder said makes sense..but what i would like an opinion about is..
even with portable o2 bottles i would worry that in the event of rapid depressurization i would also need the microphone for crew communications..which is not available on the portable o2 bottles..same goes for an in flight smoke event..the crew cannot communicate effectively
Joined: May 2000
Posts: 3,204
Likes: 2
From: Seattle
You'll just have to talk around the mask! It is, after all, an EMERGENCY situation at that point, and you might have to innovate if the pubs don't explicitly cover it.
First, you have given no reason to expect a sudden depressurization. How many have you experienced in airliners (probably a few less than I have in military fighters)? Pulling the mask away from your mouth for a few seconds to talk will NOT mean instant death. You may even find that you are adequately understandable through the soft-cup mask and the hand mike.
First, you have given no reason to expect a sudden depressurization. How many have you experienced in airliners (probably a few less than I have in military fighters)? Pulling the mask away from your mouth for a few seconds to talk will NOT mean instant death. You may even find that you are adequately understandable through the soft-cup mask and the hand mike.
Fleet Manager
Joined: Apr 2001
Aviation Qualifications: ATPL
Posts: 7,447
Likes: 310
From: various places .....
I suggest that a for-real decompression without drop down and sweep on masks is not something one would really want to contemplate as a desirable option ..... from the risk side of things the frequency of pressurisation problems is sufficient to warrant giving it serious contemplation in the circumstances described.
Joined: May 2000
Posts: 3,204
Likes: 2
From: Seattle
Well, we do have such a procedure for such situations -- using the walkaround bottles when that's the only O2 available, and it is needed. OTOH, I have not had a rapid decompression in an airliner yet, either as a pilot or SLF.
Indeed, there is lots of room for "serious contemplation" if one suddenly finds the pilots' O2 depleted, but an immediate descent would likely add more problems rather than resolving any. Proximity to divert airports with reasonable weather would be a primary consideration. However, even with a subsequent decompression, running out of fuel is NOT a viable option!
Over the Atlantic there is little need for communication, except for position reports and declaring the emergency. Hopefully all the callbacks to Dispatch were already made when the O2 problem was initially discovered, so the options in case of decompression would have been discussed at that time. Inside-the-cockpit comm may not be ideal, but it is possible. And, the fact is that you will be flying SOMEWHERE for some amount of time, so you're committed to make the best of it.
Indeed, there is lots of room for "serious contemplation" if one suddenly finds the pilots' O2 depleted, but an immediate descent would likely add more problems rather than resolving any. Proximity to divert airports with reasonable weather would be a primary consideration. However, even with a subsequent decompression, running out of fuel is NOT a viable option!
Over the Atlantic there is little need for communication, except for position reports and declaring the emergency. Hopefully all the callbacks to Dispatch were already made when the O2 problem was initially discovered, so the options in case of decompression would have been discussed at that time. Inside-the-cockpit comm may not be ideal, but it is possible. And, the fact is that you will be flying SOMEWHERE for some amount of time, so you're committed to make the best of it.
Joined: Dec 2002
Posts: 199
Likes: 0
From: flightdeck/earlyhours commute
I certainly can't see any benefit in making life more difficult than it already is. (not that it is a difficult situation...yet) There are no immediate actions from the QRH wrt B737. I would be surprised if there was anything in any other type.
If the aircraft is otherwise serviceable, then I think the best response is to continue, but have a good review of what's going on, and what you might do if other problems present themselves.
If the aircraft is carrying associated defects, such as pressurisation systems having a history of problems, then this would maybe focus attention on other immediate actions.
In the scenario given, it can hardly be expected that the interviewee would have a well considered response without in-depth knowledge of operations.
From an airline questions point of view, I would be interested in how the discussion went on.
I'm inclined to say that point of the question is to see how you incorporate new ideas and information to develop your response.
If the aircraft is otherwise serviceable, then I think the best response is to continue, but have a good review of what's going on, and what you might do if other problems present themselves.
If the aircraft is carrying associated defects, such as pressurisation systems having a history of problems, then this would maybe focus attention on other immediate actions.
In the scenario given, it can hardly be expected that the interviewee would have a well considered response without in-depth knowledge of operations.
From an airline questions point of view, I would be interested in how the discussion went on.
I'm inclined to say that point of the question is to see how you incorporate new ideas and information to develop your response.
Joined: Sep 2007
Posts: 388
Likes: 0
From: uk
I suspect that answer here, if there ever could be a "correct" answer to such a question, lies in the area of probabilities much like the basis for the MEL.
Along the lines of what is the probability of losing all crew O2 and then the on the same flight what is the probabilty of suffering a depressurisation? And so I believe such questions are merely exploratory to get a feel for how the person thinks on their feet.
Some will be quite happy with placing pax 02 bottles on F/D and making a judgement on the likliehood of a smoke problem etc whilst others will not even contemplate it and commence immediate descent and/or diversion. Even the questioners cannot know the exact answer to this question,; only what their personal take on it would be unless their ops manual specifically caters for such a scenario and I am not aware of any regulatory authorities who mandate that procedures for such should be developed.
It is simply interesting to question and discuss amongst peers but it is never intended to produce a definitive answer.
Just my tuppence worth.
Along the lines of what is the probability of losing all crew O2 and then the on the same flight what is the probabilty of suffering a depressurisation? And so I believe such questions are merely exploratory to get a feel for how the person thinks on their feet.
Some will be quite happy with placing pax 02 bottles on F/D and making a judgement on the likliehood of a smoke problem etc whilst others will not even contemplate it and commence immediate descent and/or diversion. Even the questioners cannot know the exact answer to this question,; only what their personal take on it would be unless their ops manual specifically caters for such a scenario and I am not aware of any regulatory authorities who mandate that procedures for such should be developed.
It is simply interesting to question and discuss amongst peers but it is never intended to produce a definitive answer.
Just my tuppence worth.
Joined: May 2005
Posts: 271
Likes: 1
From: On a good day - at sea
You have no choice. You need to divert.
Even with portable O2 I suspect you don't meet the CARs min O2 requirements and even if you do there is no way you are equipped for a serious smoke incident enroute.
Heck, no O2 = diversion even over Land.
Even with portable O2 I suspect you don't meet the CARs min O2 requirements and even if you do there is no way you are equipped for a serious smoke incident enroute.
Heck, no O2 = diversion even over Land.
Joined: Jul 2000
Posts: 399
Likes: 0
From: West
1) I'd talk it over as a crew and come up with our top 3 options.
2) Then I'd talk with maintenance and discuss the jet's history, potential risks and any other considerations they would like to add.
3) Then I'd talk with the dispatcher about his concerns with divert options.
4) Then I'd talk it over as a crew and come up with our final decision.
With the limited amount of information they gave you, it appears your answer is sound. Your AOM and company manuals would provide more guidance.
2) Then I'd talk with maintenance and discuss the jet's history, potential risks and any other considerations they would like to add.
3) Then I'd talk with the dispatcher about his concerns with divert options.
4) Then I'd talk it over as a crew and come up with our final decision.
With the limited amount of information they gave you, it appears your answer is sound. Your AOM and company manuals would provide more guidance.
Joined: Jul 2002
Posts: 187
Likes: 0
From: lapbandland
If its a Zero indication on the cockpit system, try breathing thru the O2
mask for a while, if you continue getting O2- its an indication error.
Continue to destination. If its a pax system indication, more problematic.
mask for a while, if you continue getting O2- its an indication error.
Continue to destination. If its a pax system indication, more problematic.
Joined: Dec 2003
Posts: 147
Likes: 0
From: South of Watford
Basically I agree with JT
Consider another route, LAX-HKG..about 15 hours in winter. Say the problem occurs 8 hours into the flight.
A cruise descent to 25,000 and continue towards destination at an appropriate econ speed with the luxury of several Japanese airports only 3 or 4 hours ahead. You may even avoid enough of the jetstream to reach HKG with sufficient reserves!
Going the other way, a diversion to ANC or YVR may be required.
IMHO, this does not require an immediate diversion to the nearest suitable airport, nor a descent to 10,000.
(I have been told that apparent loss of all pax OXY was an "indictaion" problem for one airline in the recent past, emergency descent, fuel dumping and diversion ensued....oops!
)
Consider another route, LAX-HKG..about 15 hours in winter. Say the problem occurs 8 hours into the flight.
A cruise descent to 25,000 and continue towards destination at an appropriate econ speed with the luxury of several Japanese airports only 3 or 4 hours ahead. You may even avoid enough of the jetstream to reach HKG with sufficient reserves!
Going the other way, a diversion to ANC or YVR may be required.
IMHO, this does not require an immediate diversion to the nearest suitable airport, nor a descent to 10,000.
(I have been told that apparent loss of all pax OXY was an "indictaion" problem for one airline in the recent past, emergency descent, fuel dumping and diversion ensued....oops!
)
PPRuNe supporter
Joined: Dec 2003
Posts: 1,676
Likes: 0
From: Planet Earth
Doesn't really indicate where the loss occurs, if at the beginning of the trip I would do a return, why look in the MEL? In the middle of the leg I would get the portable bottles near by and check the weather in KEF, if it's good I would do a diversion, toward the last third of the flight I would choose to land early in Ireland, I would not descend.
Joined: Dec 2003
Posts: 147
Likes: 0
From: South of Watford
Dream Land
Staying at cruise level seriously compromises your Time of Useful Consciousness in the event of a decompression.
A descent to FL 250 or there abouts is a much safer option.
Why bother to divert to Ireland (3rd scenario) when you have already been at greater risk by staying at high level? You might as well descend to FL250 and continue to destination, by that time the fuel penalty will be minimal anyway.
Staying at cruise level seriously compromises your Time of Useful Consciousness in the event of a decompression.
A descent to FL 250 or there abouts is a much safer option.
Why bother to divert to Ireland (3rd scenario) when you have already been at greater risk by staying at high level? You might as well descend to FL250 and continue to destination, by that time the fuel penalty will be minimal anyway.
Last edited by Sir Richard; 7th December 2007 at 13:22.