How would you handle this Crew Oxygen Low situation

[JammedStab]

The US Airways Airbus A330-300 aircraft (N278AY), operating as flight AWE703, was enroute at FL380 from Frankfurt (EDDF) to Philadelphia (KPHL). About 350 nm South East of St. John's the crew received a low oxygen warning indication, pressure less than 600 psi and decreasing. The crew declared an emergency and offset course to the North. AWE703 descended to 10000 feet without clearance, one flight was in trail by 4 minutes longitudinal separation at FL360. The oxygen quantity continued to decrease so the crew requested a diversion to the nearest airport. Clearance was issued direct to St. John's (CYYT) once AWE703 was clear of traffic. To expedite the landing the crew declared an emergency. AWE703 landed without further incident with ARFF on standby. Maintenance found a small leak in the pilot's oxygen mask. They swapped the captain's mask with the observer seat mask, then serviced the oxygen bottle. A leaks check was performed with no faults found, and the aircraft was released for flight.

[blind pew]

Did they not have portable crew oxygen systems or pax O2 available?
And why descend to 10000ft?

[Basil]

Situation occurred - captain made decision - aircraft landed safely.
Well done!

[latetonite]

Making a storm in a glass of water..

[s_bakmeijer]

its a bit harsh, but if anything wouldve happened, then the captain would be to blame, because the warning was registered. if there was no warning you could say making a storm out of a glass of water.

[A and C]

In the UK it would be called a storm in a tea cup ! The thread not the actions of the captain !

Accidents are made up if a number of failures that come together to form a major problem ( Swiss cheese ) in this case the captain having had one failure took action to secure the situation so that another system failure ( cabin presurissatuon or cabin smoke) would not result in a disaster.

I for one think his actions were 100 % correct.

[cjhants]

Worth reading the UPS 747 thread to see what can happen if one of the pilots` oxygen systems are not functioning properly.

Pretty much perfect decision making as far as I can see.

[NigelOnDraft]

Difficult call. You might be able to somewhat mitigate the Depress scenario by a slight descent, Pax oxy etc.

However, you are now very exposed in any Smoke / Fumes / Fire scenario.

Whilst I might not have handled it exactly as the above account states, that does not mean I criticise what this crew (apparently) did. It would certainly be a brave decision to carry on as if nothing had happened, and far riskier to crew and Pax than, say, flying a 4 Eng ac on 3 engines across the pond :ok:

NoD

[fenland787]

In the UK it would be called a storm in a tea cupWhich on first reading was my reaction too, then (and I'm not a pilot) when you start to think about it and making the assumption there is only one O2 bottle for both front seats* it sounds like he did exactly the right thing. Explosive decompression at FL380 + no O2 for either of the folk driving = not good? So get to 10,000 and then pop into your friendly local airport to pick up some more O2 is probably the right thing!
I'm sure someone who knows SOP will be along here shortly though!

* If correct that does seems odd to me?

[Desert185]

Overkill, perhaps, to prevent overkill resulting from creeping failures. Anyone can be a good Monday morning quarterback. I suspect the crew did what they did with the company's blessing. No bruised people or dented airplane. What's not to like?

[Good Business Sense]

This was always a good command course question...

To really get the discussion going.... what about it happening mid pacific ?

[Smoketrails]

cjhants,

Exactly!!!

[dubbleyew eight]

arrrooogahhh arrooogahhh dive dive dive.

(yeah I know it's not a submarine but that sounds more dramatic)

...because if there had been a situation where they needed the oxygen they would have all ended up dead. pilots, cabin crew and passengers.

when you are in command you need to make the command decisions!
:D:D:D

[Annex14]

first - the case happened two weeks ago !
second - the crew did all correct !
third - turning towards YYT took the flight off the NAT they used !
fourth - while descending outside Radar coverage TCAS / ACAS covered the remaining o,xx % of a collision risk!!
So why boiling up cold tea ??
Jo

[cwatters]

and presumably it's not just the loss of a safety system that's of concern but also where the oxygen is going and what that oxygen might do if there was a fire.

[Una Due Tfc]

"and presumably it's not just the loss of a safety system that's of concern but also where the oxygen is going and what that oxygen might do if there was a fire."

Exactly, pure oxygen coming into contact with any kind of grease and BANG

[poorjohn]

Exactly, pure oxygen coming into contact with any kind of grease and BANGIt's not a great marriage, but takes more than 'contact'.

[Ian W]

To really get the discussion going.... what about it happening mid pacific ?

Declare emergency
Get hold of a portable O2 source if there is one as cover
Set course for nearest suitable airport

Not really much else one can do

[Sky_Captain]

They declared an emergency, but descended to 10000ft without clearance? Seems odd they didn't advise about the descent but I believe the captain made the right decision.

Must be commended for following the rules and turning North when travelling west in order to get off the track for the emergency descent so as not to risk a collision with other traffic on the track!

Bravo crew

S.C. :ok:

[ManaAdaSystem]

A diversion, yes. An emergency? No. Not in my cockpit.

[Romasik]

I would rather do it with "PAN", not "MAYDAY". Emergency itself put stress on ATC and potentially other traffic, especially if someone happens to be in real emergency at the same time.

[Good Business Sense]

Hi Ian W

Descend or not ? Fuel consumption ?

[jurassicjockey]

You could argue that it's not an emergency once they're below 13000' if you like, but in my mind, that's splitting hairs. Scenario for you, you're at altitude and notice the lack of O2, but don't declare the mayday. Ask ATC for lower, and he says unable. Now what do you do? Mayday gives ATC the ability to move planes out of your way for the descent.

[framer]

"Pan Pan, Pan Pan, ABC request descent FL__ __due crew oxygen leak"
This really is a great website. Just when you're running out of scenarios to consider Pprune throws up another one :)

[Milt]

Experienced a very tight situation in an RAAF Canberra enroute Cocos Island to Butterworth Malaysia in the 60s.

Detected unusual low oxy contents beyond PNR. It took a while to figure out the rate of depletion and what to do next. The Navigator was skillfull at attempting to work out a trade off between fuel burn at a survival lower altitude when Oxy depleted. The rate of Oxy leak became the significant factor and was such that it looked close to having to abandon the aircraft before being able to reach a closest airfield.

When Oxy ran out we were forced to a much lower altitude where rate of fuel useage increased considerably. Made it to Butterworth having just enough left to taxi.

I have run short of oxygen on two other occasions with one at night not being recognised until near unconsciousness. The emergency oxy system did not work. In an annoxic state I managed to stay alive by taking deep breaths and pressurising my lungs to a maximum whilst diving steeply at a Mach number close to entering an uncontrollable nose down tuck.

The body's recovery was not like that which you experience in a decompression chamber. It was a supreme effort to continue the flight to a landing and even taxying was a huge task. The next morning I awoke to a bad headache and extreme lethergy. Perhaps there was some brain damage.

Ever since I have tried to determine the minimum blood oxygen percentage which will just keep an average human conscious. It seems to be about 65 to 70 %. Does anyone out there have a more accurate figure? Climbers of Everest should know.

[habubauza]

Correct decision was made, they really had no choice.

[archae86]

Ever since I have tried to determine the minimum blood oxygen percentage which will just keep an average human conscious. It seems to be about 65 to 70 %.

You may find this paper (http://legacy.nrao.edu/alma/memos/html-memos/alma162/memo162.html) which was prepared during consideration of construction of ALMA, a very high-altitude observatory, to be helpful. In particular the graph listed as figure 1 in section 2.1 appears to summarize the conventional wisdom on the question you raise.

Everest climbers are physiologically different from the rest of us. They find Everest Base Camp a recuperation site. For not a few of us it would be rather rapid death.

[disclosure: I'm not a pilot, but I did take an course in cardiovascular pathophysiology some years ago]

[Capn Bloggs]

When Oxy ran out we were forced to a much lower altitude where rate of fuel useage increased considerably. Made it to Butterworth having just enough left to taxi.

Wouldn't apply to commercial ops. We have to be able to cope with a depressurisation at any point on the route and be able to land somewhere with adequate fuel. If yours had been a commercial flight, there would have been plenty of divert options. I do admit though that, in your case, the camouflage and year of operation may have made a diversion to Indonesia undesirable! :)

[Tigger_Too]

Exactly, pure oxygen coming into contact with any kind of grease and BANG

It's not a great marriage, but takes more than 'contact'.



A CAPTAIN attended a meeting with a burnt face and without his usual well groomed waxed moustache. "What happened?" he was asked. "We lost cabin pressure", the captain explained, "so I grabbed the oxygen mask, slammed it to my face and—whoosh! my moustache caught fire"


True story, apparently, although quite a few years ago (not too many captains with waxed moustaches around any more!).

Also an incident where, I think, a military Hercules pilot's cheese sandwich caught fire as he was eating it. 100% O2 needs a great deal of respect.

[StormyKnight]

Yep you never know if the warning information is a symptom of a primary cause or a (hidden) secondary. Much better safe than sorry as it increases your chances of finding a effective solution to the problem, especially if it propagates.

[mkdar]

As a Captain, I will never criticize a fellow Captain's decision ending with safe operation.
However, I would have handled this deferentially;

The way I would have gone with this is to switch off the crew oxygen valve for a while to see if the leak was down stream the valve or up stream.
If you switch off the crew oxygen valve and the leak stops, then you know that the leak is down stream.
I would then continue the flight with the valve in close position , and i would brief my F/O that in case we have smoke or rapid decompression, we will FIRST switch the O2 valve on, put our oxygen masks on and continue with the memory items/QRH .
If you switch off the oxygen mask and leak continues, it means that the leak is up stream the valve, I would then calculate the rate of depletion and see if I can make the nearest suitable airport, if it appears that I will not, then , and only then , I would declare mayday and descend to MEA or 10000 feet.
Your rout off course can dictate a deferent course of action, flying over the Himalayas for instance, will force you to take escape rout maneuver into account.
In this case, they were over the Atlantic, terrain was not a factor so, I would have done what I said I will do.
This may sound scholastic but, its safe and economical at the same time.
Your thoughts please?

[ManaAdaSystem]

Provided you can switch off the crew O2... I can't.

[beardy]

I would Switch the crew oxygen sytem off initially (which you can in an Airbus330.) I would then procure an oxygen bottle from the cabin for each of the flight deck occupants, re-familiarise myself and LHS pilot with it's operation and communication facilities. Continue flight safe in the knowledge that should there be a subsequent sudden and rapid decompression (either self-induced to remove smoke or fumes, from an electrical failure or from airframe damage) that we in the flight deck have sufficient oxygen available to sustain us as we descend to a safe altitude.

ie I would replace a system, which is for emergency use only, with another. Of course this is not a dispatch condition, but nor would I treat it as an emergency, only abnormal.

I imagine that the original described scenario has lot some of it's nuances.

[mary meagher]

As a passenger waiting for departure in a regional aircraft from Dulles to Philadelphia, I was quite annoyed when they insisted on returning to the gate and taking a later flight because the Captain's emergency air bottle was U/S.

Especially as the flight would have remained below 12,000.

And then I remember that flight - can somebody give the ref - that flew on and on and on over the Med until it ran out of fuel....the entire crew and a considerable number of passengers unconscious to the end.

Don't mess about with lack of O2....

[amos2]

So, did the crew follow the procedure as laid down in their company's ops manual. I'm sure they did...end of story...shall we move on? ;)

[bobcat4]

And then I remember that flight - can somebody give the ref - that flew on and on and on over the Med until it ran out of fuel....the entire crew and a considerable number of passengers unconscious to the end.

Helios Airways Flight 522 (http://en.wikipedia.org/wiki/Helios_Airways_Flight_522)

[nitpicker330]

Really??
The cabin portable oxy bottles are not of the same standard as the flight crew fixed masks and may not provide enough Oxygen under the ambient conditions or keep smoke out of your lungs.. Not to mention you wouldn't have goggles on the portable mask. Airbus and Boeing fit the Eros Masks for a reason in the cockpit chaps....so using the portable masks from the cabin might make you feel better before any event but will probably kill you in the end....

This crew did what I would do.

Well done to them.

[cockney steve]

The Oxy. was anemergency supply, on standby until it was needed in an emergency.
Therefore a PAN would have sufficed, as there would have only been an emergencyrequiring a "mayday" if there had been a failure necessitating use of the Oxy., between the time of fault and time of reaching safety. (landing, if smoke/fumes, 10K' if decompression.

bit of an over-reaction and no biscuits with the tea.:p

(no toasted cheese sarnie either)

@ Framer :ok:

@ Jurassic Jockey....tell them the situation? 1- expedite lower or2- have a full scale Pan/Mayday on your hands....your choice, Controller!

[cosmo kramer]

There is no such thing as "declaring a PAN". :ugh:

A PAN call is just an urgent message concerning safety.

E.g.:
"PAN PAN PAN fligtxxx, we just saw a forrest fire erupt 7 nm south of yyy"

It will mean absolutely nothing concerning your priority with ATC.

[cosmo kramer]

Framer:
"Pan Pan, Pan Pan, ABC request descent FL__ __due crew oxygen leak"
-"ABC your urgent call is copied. Are you declaring an emergency?"
"Negative"
-"Roger ABC, standby for descent due to other traffic"

:E

[Una Due Tfc]

Depends on what part of the world you are in. You declare a pan with us you WILL get priority. Calling a Pan with us IS declaring an emergency. The way it was explained to me in simple terms in training was

Pan Pan Pan = we may be in danger
Mayday Mayday Mayday = we are in serious danger

[mustafagander]

On our B744 we simply get the emergency oxy bottles fitted with an Eros adapter and position them in the locker beside the pilots. Then we connect the masks and we're ready for a deco or smoke. We do, however, need to action the step to turn the bottle on. Not really a big deal, all in our EP manual.

[Ovation]

Ever since I have tried to determine the minimum blood oxygen percentage which will just keep an average human conscious. It seems to be about 65 to 70 %. Does anyone out there have a more accurate figure? Climbers of Everest should know.

Mountain climbers are conditioned to tolerate low oxygen environment, however a normal earthling will experience difficulties if the O2 level gets down around 85%. The brain and eyes need an enormous amount of oxygen so the initial effects will be impaired vision and cognitive function. The effects are insidious with primarily a feeling of warmth and euphoria, and an affected person will have difficulty recognising they are in a hypoxic state.

[FullWings]

It's an interesting scenario which has probably been used many times as a training "discussion item".

IMHO there isn't really a wrong answer to this as it's down to the discretion of the crew and how they feel about it at the time. You have to balance the probability of an explosive decompression occurring during the rest of the cruise segment (extremely low) with the risk to the airframe and occupants should this happen (high). If you have a source of supplemental oxygen, like a bottle and mask, it reduces the risk somewhat but it's not going to provide anywhere near the 100% O2 concentration, pressure breathing and protection from smoke/fumes that the aircraft system can. You can use smoke hoods with their own oxygen supply but it makes the aircraft operation more problematic than it could be. A half-way house could be to descend to an level where a portable O2 set will sustain you while you complete the descent to a breathable altitude.

It's somewhat akin to the old MEL/QRH divide: the MEL expects a further failure but the QRH doesn't. On the 777, a "CREW OXYGEN LOW" advisory indication has the explanation: "Crew oxygen pressure is low" but doesn't go on to say: "land at nearest suitable" or "descend immediately". The MEL does not allow dispatch below a certain pressure.

[beardy]

The cabin portable oxy bottles are not of the same standard as the flight crew fixed masks and may not provide enough Oxygen under the ambient conditions or keep smoke out of your lungs.

I suppose it depends on your fit. Ours are of the same quality and will last long enough to keep smoke out of one's lungs for an emergency descent until the DV window can be opened.

Still it is a good discussion point, I see Airbus has no FCOM procedure that I could find and nor do our SOPs.

[HDRW]

I once had a problem after giving blood, where I blacked-out. I didn't become unconscious, I felt "out of it", as if I was watching what was happening without being there. Then my vision went grey, and a nurse noticed I wasn't looking well, and asked "Are you OK?" - I didn't have the brainpower to answer. Then my vision went black, closing in from the outside, and she took over and she and a colleague physically led me to a bed to lie down with my feet raised, at which point I recovered my vision, and I stayed in that position for a quarter of an hour until I felt OK again. Looking back, the surprising aspects were that I remained consious but couldn't see - previously I'd thought that blacking out meant losing consciousness - and that I didn't realise there was a problem until it was too late for me to take any action of my own. Obviously the root cause of this was low blood pressure, but I'm pretty sure hypoxia from other causes would present similarly. Seeing the data on how rapidly the crew would have become incapaciated by a sudden decompression at their initial altitude, I think they acted exactly right. They had lost the safety feature that would have saved them if a fire or decompression happened, and they wouldn't have had time to get out a MAYDAY, let alone get the aircraft down to a breathable level, if it had suddenly gone from a possibility to an actual emergency. Gambling that it wouldn't happen is just not on!

[cosmo kramer]

Una:
Depends on what part of the world you are in. You declare a pan with us you WILL get priority. Calling a Pan with us IS declaring an emergency. The way it was explained to me in simple terms in training was

Pan Pan Pan = we may be in danger
Mayday Mayday Mayday = we are in serious danger

Show me the document! :E

You can't declare a PAN. It doesn't exist, there is no such thing.

A PAN call is an urgent message concerning safety, nothing more, nothing less.

That ATC may give you priority anyway, will simply be because they are aware of the poor training level of many pilots and that the will treat their so-called "PAN declaration" as a mayday call - in which case the pilot could have done it properly to begin with and use correct phraseology with a mayday call.

[beardy]

The following comes from a Eurocontrol document which can be found at
http://www.skybrary.aero/bookshelf/books/115.pdf
And quotes ICAO standard phraseology :

A distress call (situation where the aircraft requires immediate assistance) is prefixed: MAYDAY, MAYDAY, MAYDAY.

An urgency message (situation not requiring immediate assistance) is prefixed: PAN-PAN, PAN-PAN, PAN-PAN.

Make the initial call on the frequency in use, but if that is not possible squawk 7700 and call on 121.5.

Pan exists, has a meaning that most of us understand, it is not an urgent message, it is an urgency message meaning that the caller requires urgent attention (but not immediate assistance), pedantry I know but important. Neither Mayday nor Pan is "declared" they prefix a message of the relevant category. Luckily most Air Traffic Controllers, worldwide, are trained to be aware of ICAO standards and of the differences in their countries.

I am so sorry for the thread drift, I was enervated by the previous poster's assertions.

[Una Due Tfc]

Well I've never had somebody call a Mayday on me (and hopefully never will), but I've had a few Pans, 1 for an engine failure on a 744 and a few for medicals and hydraulic failures etc, In essence you are right it's not an declaring an emergency in itself but I've never had a Pan called by an aircraft that wasn't looking for a diversion or looking to deviate due to an emergency. I hear Pan or Mayday then I'm treating you as an emergency aircraft unless you tell me otherwise

[NigelOnDraft]

Another way of looking at this is using the Prefix appropriate to the service you are (or not) getting from ATC.

Slow Oxy problem, decide descent in next 5 mins is a good scheme.
"Request Descend FL150 for minor tech problem"
"Maintain FL350, will check with next sector"
"Pan (x3) request descent" gets the message across

i.e. use the prefix to get the service you need, not according to the problem (which ATC can do diddly squat about anyway).

NoD

[Basil]

HDRW, What you describe is similar to blacking out due mishandling one's physiological response to high G. --- Don't ask :O

[Iron Duke]

As Basil said ... 1. Situation 2. Crew response 3. A/C landed safely .. Perfect.

Statistics may play a part in this ... It is statistically unlikely to have a further issue with pressurisation or smoke/ fire in cockpit. In this case maybe portable oxygen/ Drager hoods could have sufficed as back up until a diversion could be effected at cruise levels, thereby minimising any proximity conflicts. For me Land As Soon As Possible is correct.

If a decision is made to operate outside (or, you have no choice) of your NAT procedural clearance then it is a MAYDAY call. Another scenario where this can happen is on the high latitude Canadian routes with a LOW FUEL TEMP warning, and either an acceleration or a descent is decided upon ... MAYDAY.

I. Duke

[cosmo kramer]

Neither Mayday nor Pan is "declared" they prefix a message of the relevant category.

You can declare an emergency using "mayday". You can't declare anything using pan. Which is exactly what the document says that you posted.

Also, mayday has to do with YOU. You can't declare an emergency on behalf of others. However, you can use Pan to send an "urgent message regarding safety", that being other aircrafts or people on ground. Hence, the example in my previous post with the forest fire. Or you can use Pan to tell ATC that you saw another plane crash, as another example.

[beardy]

Cosmo,
Please read these links regarding the use of Mayday and Pan, one is from the FAA the other from the CAA (UK.) Your view of the limitations of each phrase don't seem to be represented here. Also please note there is no reference to any form of 'declaration.'

http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0603.html

http://www.atac.ca/web/images/Documents/Phraseology%20Guide%20for%20Commercial%20Pilot.pdf

[framer]

Tell that to the ATC who told me I would have to 'declare a Pan' if I wanted priority tracking to the field.

[cosmo kramer]

Please read these links regarding the use of Mayday and Pan, one is from the FAA the other from the CAA (UK.) Your view of the limitations of each phrase don't seem to be represented here.

From the CAA document:
"An urgency message (situation not requiring immediate assistance) is prefixed: PAN-PAN, PAN-PAN, PAN-PAN."

That is exactly what I said. A Pan call is nothing more than an urgent message. You can not expect immediate assistance, since you do not require it (that some ATC may give you the same assistance as if you declared an emergency, is because they are nice, cautious, bored, whatever... But you are not entitled to any priority or special treatment.

Why the reluctance to use a proper mayday like the crew of the US Airways did?
They wanted to descent and required immediate assistance in doing so. Why do you people have a problem with a mayday call. You don't have to pay for it. :D

Also please note there is no reference to any form of 'declaration.'


From your document:
"Fuel Emergency or fuel priority are not recognised terms. Flight crews short of fuel must declare a PAN(????) or MAYDAY to be sure of being given the appropriate priority."

...thought I wonder how the English CAA would want you to declare an "urgent message".

Mayday = distress = emergency = something your can declare
Pan = urgent message = something you can't declare

[cosmo kramer]

... and just for good order, the section about minimum fuel quoted above has been changed. Though not relevant for this thread:
http://aviation.osu.edu/wp-content/uploads/2012/11/ICAO-changes-for-minimum-and-emergency-fuel.pdf

[VinRouge]

It's all about risk mitigation. Descent without clearance is less risky than a measured approach, a discussion amongst the crew and a plan of action?

Really?

What is the probability that there will be a fumes or depress event whilst the oxy was low, vs the risk induced by busting your level in busy procedural airspace?

[VinRouge]

Ever since I have tried to determine the minimum blood oxygen percentage which will just keep an average human conscious. It seems to be about 65 to 70 %. Does anyone out there have a more accurate figure? Climbers of Everest should know.

Having done hyperbaric training with a O2 sensor on in the last 3 months for my requal, I can tell you that by 70% you are symptomatic, (for me, tingling fingers and loss of colour perception) 60% your judgement is affected and by 50% you are on the verge of losing the chance to detect an issue.

The worst feeling was going onto 100% at the end of the run, the oxygen flushes the co2 out of the blood and your blood 02 initially takes a huge dive. The sense is pretty nasty and paradoxically if hypoxia you may be tempted to remove oxygen fearing that the supply is contaminated.

[dkz]

Great job, we can argue on a forum about the "need" to declare an emergency but probably 99% faced with the same issue would.

The point about the portable oxygen is not exactly valid because of comms, oxy pressure at high altitude and lack of smoke goggles. On the portable mask there is no mic, on the next sim try to handle an emergency descent without one ... also try a smoke drill without goggles.

[beardy]

Cosmo,

I take the point about declaration.

Fuel Emergency or fuel priority are not recognised terms
They still are not, minimum fuel has now become one, with a specific meaning that does not preclude the use of pan nor mayday.

From the CAA document:
"An urgency message (situation not requiring immediate assistance) is prefixed: PAN-PAN, PAN-PAN, PAN-PAN."

That is exactly what I said. A Pan call is nothing more than an urgent message.

There is a difference between a message that is urgent (of itself) and a message of urgency i.e. one that relates to a situation that requires urgency. So if you wish to'declare' something it would be a situation that requires urgent (as opposed to immediate) attention and one that gets adequate RT priority (greater than a normal message, but less than a mayday.)

There is no problem with declaring a mayday, it can always be downgraded to a pan or rescinded.

dkz,

The point about the portable oxygen is not exactly valid because of comms, oxy pressure at high altitude and lack of smoke goggles. On the portable mask there is no mic, on the next sim try to handle an emergency descent without one ... also try a smoke drill without goggles.

There is no problem with oxy pressure at alt, think about cabin crew procedures. I have a mic on my headset which I wear over my EROS (but only to use the earpiece, but the mic is still available.) Good point about goggles.

Of course in extremis the smokehood is available, but I wouldn't want to rely upon it in an emergency descent on emergency electrical power ( a situation that can arise when following Airbus drills for smoke and fumes.)