No O2

[R2000/1830]

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.

[punkalouver]

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.

[Intruder]

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...

[Colocolo]

.....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

[westinghouse]

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.

[john_tullamarine]

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

[bflyer]

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

[Intruder]

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.

[john_tullamarine]

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.

[Intruder]

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.

[Shiny side down]

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.

[Starbear]

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.

[nnc0]

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.

[None]

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.

[Flight Detent]

None...

I'm thinking after all this talking, you may be interrupted by approach control wanting you to descend at your planned destination....problem solved!

Cheers...FD :uhoh:

[Intruder]

You have no choice. You need to divert.
OK. The OP said you are 'in cruise between NY and London.' WHERE do you divert to? WHY there?

[boofta]

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.

[Sir Richard]

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! :\ )

[Dream Land]

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.

[Sir Richard]

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.

[nnc0]

Ok I'm really puzzled why so many would continue to destination.
You're not legal (airworthy).
And, How can you possibly continue to dest'n knowing how seriously crew performance would be reduced in a real smoke emergency? You're betting it won't happen?
(We had three of these last year in one particular fleet in the span of two or three weeks before determining what the problem was. All three were immediate diversions and not a single eyebrow was directed toward the crew.)

[Dream Land]

Sir Richard, point taken!
(We had three of these last year in one particular fleet in the span of two or three weeks before determining what the problem was. All three were immediate diversions and not a single eyebrow was directed toward the crew.)
Today 05:58 nnc0, can you give us more details about actions taken by the crews, did they descend, bring portable O's to the flight deck, try the system to verify the indication etc? :confused:

[Intruder]

You're not legal (airworthy).
Please provide some kind of reference for your opinion.

Any time you are in a configuration not permitted by the MEL/DDPG, I suppose the airplane is technically "not airworthy" (there was an interesting discussion over the past 2 months in AOPA Pilot magazine by the association lawyer on the issue, and there is NO "black & white"...). However, there are a plethora of such configurations that, even though they would not permit takeoff, do not require an immediate or "as soon as possible" landing. Did the BA pilot who flew on 3 engines from LAX to Manchester (because he ran low on fuel and couldn't make LHR) have a 3-engine ferry permit? Was he "not legal"?
This is what our 747 Classic Flight Handbook has to say on the issue:
There are some situations which always require landing at the nearest suitable airport. These situations include, but are not limited to, wheel well fire, cabin smoke or fire which persists, lower cargo compartment fire, main deck fire, dual hydraulic system failure, electrical faults which result in only critical systems remaining, or any other situation determined by the crew to present a significantly adverse effect on safety if the flight is continued. In each case, it is the responsibility of the Captain to assess the situation and execute sound judgment to determine the safest course of action.
Since the FAA approves the FHB, the FAA has also agreed that except in the named circumstances, it is up to the Captain to determine whether an immediate landing must be made.

THAT is why some would continue to destination, depending on the totality of the circumstances.

[Mephistopheles]

We had a similar incident in our airline (GF) about a month ago from BAH to KUL. They lost all the crew O2 about an hour & a half before destination so they landed at the nearest suitable airport. The management & the trainers all agreed with the Capt's decision. After all who wants to keep pushing when you have a suitable place to land? Since it always seems that when 1 thing goes wrong there are bound to be other problems cropping up. As they say "Best to think about it on the ground"

[peacock1]

Having done very many crossings of the pond, I would consider that the interviewee's answer is the best I've read so far. No O2, = not going far!
(of course I'm assuming that it's the cockpit gaseous oxygen that has depleted, as the SLF O2 is chemically generated). Upon noticing that you have little or no cockpit O2 left, it's down to 10,000 or MSA if higher,(it is'nt on the NYC-LHR route unless if over Greenland), and, yes, fuel burn will be much higher, thus it is unlikely that you will make landfall eastbound at this lower altitude. Upon consideration, this was a clever interview question. The answers from candidates would be expected to be commensurate with experience. Don't know your experience level, but in any case, your answer was SAFE.
Hope this helps, and good luck with those interviews:ok:

[Intruder]

If you consider a blind descent to 10,000' over the middle of the Atlantic as "safe" under the given conditions, I certainly wouldn't hire you. To risk fuel starvation because of an abnormal condition that has no immediate adverse effects is IMO a bad decision.

[Brian Abraham]

To risk fuel starvation because of an abnormal condition

Intruder - Don't you heavy iron guys carry fuel for pressurization failure ie transit at 10,000 to an alternate from any point along track?

My reading of FAR 121.329 and 121.333 prompts me to agree with the interviewees (R2000/1830) answer. Procceed at 10,000. 121.333(b) in particular I think is most relevent.

"Crewmembers. When operating at flight altitudes above 10,000 feet, the certificate holder shall supply enough oxygen to comply with §121.329, but not less than a two-hour supply for each flight crewmember on flight deck duty. The required two hours supply is that quantity of oxygen necessary for a constant rate of descent from the airplane's maximum certificated operating altitude to 10,000 feet in ten minutes and followed by 110 minutes at 10,000 feet. The oxygen required in the event of cabin pressurization failure by §121.337 may be included in determining the supply required for flight crewmembers on flight deck duty."

That is, no oxygen, no above 10,000. (As I read it. Stand to be corrected)

R2000/1830 - Stick to the radials rather than them whining turbines. (Money aside)

[Dream Land]

Brian, I think most here understand the regulations concerning a pressurized aircraft, no one will debate that point, 10,000 ft is where we descend to when the cabin depressurizes, yes we must also carry fuel for this worst case scenario, but going to 10,000 ft. immediately after the loss of crew O2 would not be my immediate action unless ample diversionary airports are available, is this an FAR violation, don't think so.

[FE Hoppy]

I would follow the procedure as layed down in the QRH.
For my type that says
Descend to 10'000 or MEA.

Because of this we would have to divert.

As I would have been keeping track of wx and availability of en-route divs throughout the flight there would be no need for desicion making as to where to go.

The type of descent would depend on where I was ref nat tracks.

The procedures for initial descent out of NAT airspace are well documented.

Once under the tracks and pointing in the right direction I would look again at the fuel required and wx and either cruise descend with protable O2 near by or get down early to the MID teens and then cruise descend from there.

[Intruder]

That is, no oxygen, no above 10,000. (As I read it. Stand to be corrected)
Your reading is correct for normal circumstances: To takeoff, you must have the appropriate amount of fuel and oxygen loaded. However, FAR 121.329 and .333 do not specifically address the failure of the primary crew oxygen system ONLY. The FAA approved FHB/QRH/Abnormal procedures take over at the point of a system failure.

The OP addressed ONLY a failure of the primary crew O2 (or O2 indication). There has been NO depressurization or indication that one should be expected. Our procedure states:

When the fixed oxygen supply becomes depleted during flight, the crew becomes vulnerable to both smoke
and loss of cabin pressurization.
The following steps should be accomplished to provide the greatest margin of safety under the circumstances:
• Place the cockpit portable oxygen bottle in a location readily available to the Captain.
• Retrieve the two Upper Deck Portable Oxygen Bottles and place one in a location readily available to the First Officer and the other in a location readily available to the Flight Engineer.
• Plan to land at the nearest suitable airport.
• Analyze the possibility of descending to a lower altitude, considering available fuel vs. time to destination. Descent should be a secondary consideration to maintaining adequate fuel reserve, particularly on overwater flights or when traversing widespread areas of poor terminal weather.
• Review the Cockpit Fire/Smoke Evacuation and Rapid Descent Checklists.
Note that the nearest "suitable" airport may NOT be the nearest airport at which an "immediate landing" might be made. It would more likely be the ETP airport or another designated enroute airport where weather is suitable and maintenance is available.

Note also that descent is specifically a "secondary consideration." There is NO reason to create another (i.e., low fuel) emergency while attempting to mitigate a _potential_ problem.

[Brian Abraham]

the crew becomes vulnerable to both smoke and loss of cabin pressurization

Intruder - Many thanks. I was going to reply with the 121.337 Protective breathing equipment requirements. Interesting though the approach taken by FE Hoppy's company which is in line with the original proposition. More than one way to skin a cat.

[Spooky 2]

Well here is a real life story and I'll try to make it short. The B727 was en route from Washington, Dulles to Salt Lake City. There was an FAA Air Carrier Inspector in the jump seat just aft of the Capt. When about 200 miles east on Denver the Capt. looked back at the S/O panel and noticed the O2 was at Zero. Just about that time the FAA asked to be excused to go back and use the lav. As soon as he was out of the cockpit the Capt called this O2 problem to the S/O's attention and everyone checked their O2 regulators. The F/O's regulator had been left on, thus depleting the O2, Quickly the Capt. moved the Observrs seat regulator to the On position. When the FAA returned and after few minutes the Capt. called the O2 problem out to the crew and said "everyone check their regulators", Well the FAA guys was mortified to find his regulator in the on position. Quickly the Capt. posed the question....should we divert into Denver? The FAA responded with a "please, whatever you do, don't do that". So they continued on to Salt Lake City without further incident. Not sure weather they decended or did any other precautionary planning. The poor FAA guy could probably see him self writing officail letters explaining his actions for the next five years! I can tell this story today as the Capt. has since passed away.

[FE Hoppy]

and what about the complicit SO?

[Spooky 2]

Complicit in what sense? Maybe the thing went to zero 30 seconds before the Capt noticed it. I have no idea how to implicate the SO as it was the FO's regulator that originally started the sequence of events.

[FE Hoppy]

As the whole crew, Cpt, FO, SO(FE) were aware of the real problem and tricked the FAA guy into a very poor call. Then be glad it didn't turn to pooh.
The voice recorder would have recorded the whole thing.

[ppppilot]

Airbus 343. Pax O2 is chemical and you don't have indications. Crew O2 low is a caution msg (amber) and OM says under abnormal procedures, that you may or not have O2. :hmm:. I would rather prefer something like "If you can read this, then you are not dead. That is a good start"
Then, no diversion. Anyway, accidents are always spying me, to change my sweet life. So take two O2 portable bottles into cockpit and connect both quick donning masks to them, they use the same fast connector :). In case you don't have the same connector, then you have a problem cause the first aid masks, mix the O2 with fresh air and if instead air you are into smoke atmosphere you are going to be a passive smoker. Another option are the smoke hoods that gives you 15 minutes but no communication with the other pilot or ATC. (very noisy the O2 generator).

[Spooky 2]

This probably means very little but in the B777 in the QRH Unannunciated Checklist there is no guidence regarding crew action that may be associated with an EICAS message that says Crew Oxygen Low. Ditto for a Pax Oxygen Low message. This assumes that your 777 is equipped with a gaseous system as opposed to the 15 or 20 minute canisters. I guess it's fair to say that they will leave it up to the crew to act in the most prudent, safe manner to get the airpane and pax to their destination or alternate.

[john_tullamarine]

Well here is a real life story and I'll try to make it short

.. I think we all have a story or three a bit like that one .....

[None]

Flight Detent wrote,

"None...

I'm thinking after all this talking, you may be interrupted by approach control wanting you to descend at your planned destination....problem solved!

Cheers...FD "

Well, that's the beauty of SATCOM. A three minute conference call is all you would need. Since this is not a "fast" emergency, there's time to think and talk about all of the implications. That's just me, and not the only way to handle this one.

[peacock1]

For the attention of Intruder, no-one flying the Atlantic should be flying "blind" in any case - that's why all proficent operators will have not only the closest alternate airport pre-programmed in their FMS, but also the approach in use, for the conditions reported.
Most Atlantic crossings these days are performed by Aircraft operating under ETOPS constraints, one of which is the carriage of fuel for the (hopefully) hypothetically implausable "critical fuel scenario".
Therefore, a descent to 10,000 ft, in the event of a loss of cockpit O2, over the Atlantic, and obvious diversion, to repair , is the only course of action I could consider.:)

[stator vane]

bloody hell on some of these questions on initial interviews!

i wonder what they do on their days off?