This is a subject close to my heart. But first, just a jogged memory.

I was pre-flighting a medium weight turboprop prior to a passenger flight. My usual test for O2 first flight of the day, was to turn the oxygen off, then keep breathing until I was sure the valve had actually closed.

One day I just kept breathing. I put my finger in the outlet duct while looking in the mask. I could see my finger! The fleet's masks had been cleaned and some NRVs had never been replaced. They'd been flying like that for some days.

You can imagine the potential danger.


The jogged memory was about a Navajo I used to fly occasionally while training crews on a turboprop for most of the time. It was a nice little break, lovely countryside, and an undemanding schedule. But, I often just didn't feel right as I approached say, 8,000 feet.

It was hard to tell what was wrong, but something was. A feeling that the aircraft was balanced on a needle point. Move, and it would fall. I loved aerobatics, and if no pax, would throw it around as hard as I dared. Nothing. All normal. It was just when trying to maintain a smooth flight with a steady power setting.

Long story short, I had a huge medical, and nothing was found. Rather worrying. Then another pilot reported the same thing. The Air Force did his tests. EEGs, the lot. Nothing found. The aircraft was fitted with CO detectors. Nothing.

I reported that the sensation Always went away almost as soon as I dropped the nose for the decent. ( Change in engine note perhaps. )

One doc made the remark that up to now, he'd never had sound vibrations affecting crews, but 'it was going to happen one day.' Maybe. I tried different engine settings but it didn't help. Not enough change perhaps.

The thing is, just imagine if the two of us had been in that aircraft at the same time. Major red herring.

That was in 1979, and never happened again in thousands of hours of flying, though one significant factor has just come to mind. Somewhere in the same year, I was treated with Tetracycline for an ear infection. Can't have been too near the time, or it would have been obvious, but I've had tinnitus ever since, so just maybe a connection. Just a hint of the wrong signals going in from the balance circuits, but not enough to give the game away perhaps.

By the way, there is a school of thought that links that antibiotic with tinnitus. Be careful - Tinnitus sucks.:(

Barrett, as an aside, the medical profession may not refer to such things as a rebreather bag (or in fact the item I was referring to is incorrectly named in our paperwork) but I can tell you that three airlines I know of refer to them as such.

Not that we're saying it's correct, it's just the term most cabin crew would know them by. Ambu Bag is probably a brand name for the same thing mentioned before. It's what I know it as, I don't doubt medical personnel would call it something else.

http://i1006.photobucket.com/albums/...rebreather.jpghttp://i1006.photobucket.com/albums/...ich/th_BVM.jpg
Photo sizes have got a bit strange,but the large photo is a rebreather or reservoir bag - the patient needs O2 but can breathe unaided.The small photo is Bag Valve Mask(Ambu bag) - the patient can't breathe unaided, so the semi-rigid bag is squeezed to inflate the lungs with O2.

Pics
 

Yep, them's the ones!

Though it seems the mask with rebreather/resevoir bags are disappearing from aircraft as I now see more without the bag than with. Perhaps because of the reasons mentioned above that they confuse crew as to what they actually do? Would be interested to know why they seem to be getting changed out.

Is it possible that the confusion is because the term reservoir/rebreather is being used interchangeably?

The technical discussions about mask variants are very interesting but I think that they are obscuring a key concern: that of the "panic" expressed from the flight deck.

No doubt the call across the PA was in line with procedures and there was no panic from the pilots, but it does seem to have been perceived as such by some if not all of the passengers. I could certainly believe that there would have been an abruptness or a seriousness of tone which would not be present in Capt Speaking's regular "cruising at 35,000' " announcement which would have been picked up by passengers and caused the more nervous to become genuinely concerned about.

Now obviously if you have just put the aircraft into a rapid descent due to pressurisation concerns the pax will notice and you can afford a tone of urgency but with no other indications it could be possible to adjust tone or wording to make the important message appear routine.

Passenger worry clearly isn't the overriding factor in this situation (that would be having the crew breathe and function normally) but I would far sooner read headlines like "Passengers unaware while pilots flew on oxygen" than some of the guff which we have seen with this incident.

Problem is disguise it as something else to appease some nervous passengers and it may not have the desired effect of getting all the crew members attention and getting them all where they are needed, or might need to be.

As for the tone, well in this case it would seem the pilots thought they had a genuine and fairly urgent problem and I suspect even with all the PA training in the world their tone was going to appear less than routine.....

IMHO when the chips are down you just have to expend with the huggy fluffy stuff, get the job done, and sort the PR/nervous passenger/litigious passenger aspect of it later. FWIW I doubt the incident has been accurately reported here or in the general press so the stories about the PA are irrelevant - most of the "guff" would have been posted anyway.

Wiggy, initial post/report on here by myself was bang on accurate, I was there !!!! What ever the press write is up to them.

I still think what you thought was a panicked call from the flight deck was a normal call heard with the pilot trying to talk with a full O2 mask, as illustrated earlier, being wrapped round his face. This distorts voice and is not uncommon when a depressurisation has occurred and the crew are trying to contact ATC and having difficulty in being understood.

From a purely physical aspect, making yourself heard when wearing a full face mask, not to mention the breathing rate experienced during a 'pucker moment' would of course sound less than 'routine' to a passenger.

When practicing depressurisation PAs in the sim wearing a mask at a previous company, I was very surprised to see a video of myself later on... sounded nervous as hell, even though being i nthe sim I wasn't. The extra effort required probably made it sound so, I would assume the same in this situation. Wouldn't blame them for sounding a bit jittery though- adrenaline does that to people :ugh:

Other than checking the aircraft over, what action is taken to determine the cause?

Blood samples from the crew? 20 questions about what they ate? Is there a established plan of investigation in these circumstances?

batboy

I don't doubt that you were there.

Having donned the full face mask (in the simulator) on many occasions and tried to make a suitable soothing PA, I suspect, as do others, that what you describe as:

was in fact, as lakerman said:

If the press and other's want to attribute that unusual sounding PA as panicked, then IMHO I think "guff" still applies.

Pilots very occasionally have to function under great stress. If a pilot is the sort of person to panic then they would not have ever passed through the many hoops of training nor be able to cope with the job in general.

I have been under great stress, I have seen others under great stress what I have never heard is a pilot sounding panicky.

batboy1970, your original post failed to get the phrase used correct, you misinterpreted the fact that a CC member carried an oxygen bottle and you set so many hares running that the story has even made it into the German newspapers.

On behalf of all the pilots in the world thank you for the disservice.

Without wanting to sound too blasé, such events are more common than perhaps some may think. 757s and 146s have both had a notorious history and when both types were more widely used in the UK, one never needed flick too far through the latest MORs to find similar events, having been recently reported. Although the issue does seem to have improved a lot over the years.

Full face masks, PAN calls, paramedics, cabin crew having O2 ready etc are the routine drills for such events. What would have been more worthy of note is if the crew had not carried out the above drills with such a problem.

I myself have suffered from contaminated air on very short final once. The symptoms were a combination of a mild headache mixed with a rather 'tipsy' feeling, similar to what one could expect at closing time, after one too many!

Why is this thread surviving on R&N? Far more relevant threads that fit the forum description have been binned or demoted in the past. Because the mods have allowed it to develop to five pages of albeit well intentioned passenger questioning and mildly interesting but totally irrelevant breathing apparatus discussion it has attracted the attention of the Idiot Press and they have quoted excitable guesswork/nonsense that has turned a routine turn-back into something it wasn't, complete with "panic on the flighdeck".

So mods, why is it still here?

It was so "bang on accurate," including your description of how the flight crew was making all possible speed back to LHR in their hysteria, that somebody who was actually a pilot had to point out that outbound, they were flying into a strong headwind and when they reversed course, guess what happened? (I'll leave you to puzzle that out.)

Much of "what the press wrote up" is, of course, the obvious result of having read your "bang on accurate" assessment, as an Expert Passenger, of what transpired. Or didn't.

Another example to us of the accuracy of "witness" statements. Ever a challenge in the accident investigation field.

The observation are of what the witness experienced or thought they saw, interpreted in their narrow field of experienced to be later intrepreted by those experts with specialized knowledge and experience.

It's up to us, the reader to interpret through those few experts that do have the benefit of specialized knowledge and experience appropriate to the subject.

Sometime we depend on the media to search out and find the more appropriate interpretation, while all too often we subcomb to being lazy and allowing the media to just print the words that sell to their readership.

If the media is so dumb that they can't bother themselves to search for the realities than to simply quote an unvetted PPrune source than we have only to blame the news writer and not the witness.

Sorry, that was a poor choice of words.

I meant "simple" as in a textbook event which all flight crew train for regularly. Nothing "out of the ordinary" so to speak.

Mods

Could I throw my weight behind BitMoreRightRudder

The direction this thread has taken - whilst fascinating - is far removed from what actually happened. If we wait for the AAIB report we could then start a whole new thread based on a detailed description by a trusted agency.

I vote to to lock this thread.........

under those standards

why lock only this thread :confused:

OK - split off the entirely spurious posts about decompression and oxygen masks and repost them in the medical section.

Then lock the original thread awaiting some actual facts to emerge from the investigation.

We can then have a completely different set of discussions that don't include the word "rebreather".........