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GordonR_Cape 22nd Aug 2019 18:04


Originally Posted by double_barrel (Post 10551648)
Thanks, that's very helpful. And as you say, it goes a long way to explain the lethality of CO, I knew its binding to Hb was tenacious, but had no idea it was locked-in like that. I think I will take a look at the underlying biochemistry out of interest.

Thanks to PDR1 for his definitive answers.

I am not an expert, but also curious about the reversibility of COHb binding. Wikipedia gives some clues: https://en.wikipedia.org/wiki/Carboxyhemoglobin

COHb has a half-life in the blood of 4 to 6 hours.

Supplemental oxygen takes advantage of Le Chatelier's principle to quicken the decomposition of carboxyhemoglobin back to hemoglobin:
HbCO + O2 ⇌ Hb + CO + O2 ⇌ HbO2 + CO
My interpretation would be:
1. At body temperature in a living being, CO poisoning is slowly reversible through the circulation.
2. The absence of oxygen and blood circulation, and/or low temperatures would "freeze" the binding process.

BigEndBob 23rd Aug 2019 20:21


Originally Posted by nonsense (Post 10547308)
And yet so many people have died from CO in cars, on boats, without noticing anything else in time.
Empirically, your logic is wrong.

My motor bike would stink my garage out and i would leave long before it gave me any ill effects.
People have left key less car engines running, but modern cars have cats, so not much smell.
The few problems i have had with light aircraft gave me head aches which turned out to be faulty exhaust and a crank vent that wasn't blowing out board and a split in the scat hose to the windscreen de misters. All very smelly.

Pilot DAR 24th Aug 2019 02:53

I can assure readers that CO is a cockpit hazard at concentrations much less than are "noticeable" by smell. Detection requires an appropriate detector, Your nose will not provide adequate warning - mine didn't.

A and C 24th Aug 2019 17:10

I simply cant understand what part of the colourless odourless gas part of the Description of CO people on this forum have not got into their brains.

Each year I see in the press tragic events from CO poisoning from gas stoves, central heating boilers and other combustion sources , there are a great number of regulations in the industrial and domestic environments, this reflects the danger that the authorities see CO poses to the users of such equipment simply because of the subtle way CO incapacitates it’s victims.

Both the aircraft manufacturers and aviation authorities recognise the danger of CO and put in place regulation mitigate the risks .

Yet with all this evidence some above think they will smell the CO and be able to something about is, perhaps the only comfort we can take from this attitude is these people will simply not know what killed them.

Chronus 24th Aug 2019 19:05


Originally Posted by A and C (Post 10553331)
I simply cant understand what part of the colourless odourless gas part of the Description of CO people on this forum have not got into their brains.

Each year I see in the press tragic events from CO poisoning from gas stoves, central heating boilers and other combustion sources , there are a great number of regulations in the industrial and domestic environments, this reflects the danger that the authorities see CO poses to the users of such equipment simply because of the subtle way CO incapacitates it’s victims.

Both the aircraft manufacturers and aviation authorities recognise the danger of CO and put in place regulation mitigate the risks .

Yet with all this evidence some above think they will smell the CO and be able to something about is, perhaps the only comfort we can take from this attitude is these people will simply not know what killed them.

https://www.gassaferegister.co.uk/me...ade-review.pdf

Here is an extract from it:"Safety challenges For the 20 per cent of respondents who believe gas safety has worsened, eight times out of ten they say it’s because customers are getting gas work done on the cheap. Illegal gas fitters – people who work on gas who are not Gas Safe registered – and under-skilled engineers were given as key reasons by those who thought gas safety had worsened. Illegal gas fitters are believed to be cheaper, so consumers need to be aware of the risks they are taking to save money. A few training bodies mentioned that some training is less thorough, although not all think this is the case, and others cited under-skilled gas engineers. "

The irony in this case is that the pilot was a heating engineer who one would have expected was well versed in the case of Gas Safety, but seems he may have succumbed to the effects of a faulty heater whilst conducting what appears to have been an illegal flight on the cheap one might say, rather than pay the going price charged by an organisation fully licensed and approved to do the job safely.





BFM 25th Aug 2019 08:20


Originally Posted by PDR1 (Post 10550358)
CO poisoning produces permanent damage to red blood cells - it's a signature which remains and can be identified even in a long-deceased body and it gives fairly precise values of the scale. CO poisoning is not just a matter of lack of oxygen (as happens with CO2) - it is actually a poisonous gas. CO "locks" the haemoglobin in the blood such that it can't take oxygen even when it's present. If you suffer CO poisoning beyond a certain level even getting you away from the CO and giving you 100% oxygen via a mask won't save you - you will die unless you are given a rapid and massive transfusion of red blood cells (which is rarely possible).

So the detection of CO poisoning in "a body that had been under seawater for so many days" is not in any way remarkable or strange.

PDR

In fact it is worse than that; as well as haemoglobin in the blood the body's muscles contain myoglobin to which carbon monoxide binds in the same way as I outlined previously. However, I'm not aware of any research into the natural degradation of carboxyhaemoglobin over time and under high pressure in an anaerobic environment, so while the measurement can be made accurately I'd be uncomfortable with the statement that it was a precise representation of the level at impact.


Originally Posted by Genghis the Engineer (Post 10550817)
There is evidence that sedentary smokers are less prone to hypoxia than fit non smokers.

I have no idea if that maps to CO poisoning, but I suppose it's at least hypothetically possible.

G

They are no less likely to be hypoxic on assay of blood gases but as they are used to permanent mild hypoxia (and of course low level carboxyhaemoglobinaemia) their nervous system tolerates it better.

PDR1 25th Aug 2019 08:47


Originally Posted by BFM (Post 10553634)
However, I'm not aware of any research into the natural degradation of carboxyhaemoglobin over time and under high pressure in an anaerobic environment, so while the measurement can be made accurately I'd be uncomfortable with the statement that it was a precise representation of the level at impact.

Papers on the subject are reference in the page I cited above.

PDR

BFM 25th Aug 2019 21:22


Originally Posted by PDR1 (Post 10553644)
Papers on the subject are reference in the page I cited above.

PDR

Not in a high pressure environment. I agree with your comments in terms of time and temperature but I don't see that studied. It may well not matter, but we just don't know.

BigEndBob 30th Aug 2019 21:34

So has this aircraft been lifted from the sea yet?
And if not, why not.

Also i noticed the CO detector in one of our aircraft has the name SleepSafe on it.
Bit late if it changes whilst you are asleep.
The electronic one i use in my camper is what needs to be fitted to all aircraft with exhaust heaters.
They are fairly cheap.
But would it be heard through noise cancelling headphones?

Just ordered two with digital read out, less than £12.

Mike Flynn 12th Sep 2019 20:59

The latest AAIB bulletin featuring this accident is here https://assets.publishing.service.go...019_Lo_Res.pdf

The AAIB published Special Bulletin S1/2019 on 25 February 20191 to give preliminary information on the investigation and general information about how aircraft registered in the USA may be operated between the UK and France.
This Special Bulletin contains medical information relevant to the accident to highlight the implications of that information to the General Aviation community.
Results of toxicology tests
Toxicology tests on the blood of the passenger showed a carboxyhaemoglobin (COHb) saturation level of 58%. COHb is the combination product of carbon monoxide (CO) with haemoglobin, the oxygen-carrying protein molecule contained in red blood cells.
CO is a colourless, odourless gas produced from the incomplete combustion of carbon-containing materials. It readily combines with haemoglobin in the blood, decreasing the carriage of oxygen and causing a direct effect on the performance of those parts of the body which rely on oxygen for proper function. A COHb level of 50% or above in an otherwise healthy individual is generally considered to be potentially fatal.
In this type of aircraft, the cockpit is not separated from the cabin2 and it is considered likely that the pilot would also have been affected to some extent by exposure to CO.
Symptoms following exposure to carbon monoxide
Exposure to CO can lead to damage to the brain, heart and nervous system. The symptoms of CO poisoning worsen with an increasing percentage of COHb as detailed in Table 1.
COHb level
Symptoms
Less than 10%
None
20 to 30%
Drowsiness, headache, slight increase in respiratory rate, dizziness
30 to 40%
Impaired judgement, difficulty breathing, blurring of vision, bad headache, increasing drowsiness, stomach pain
40 to 50%
Confusion, blurred vision, shortness of breath, pounding headache, vertigo, loss of coordination, chest pain, memory loss
Over 50%
Seizure, unconsciousness, heart attack
Table 1
Symptoms of increasing levels of COHb
It is clear from the symptoms that exposure to CO can reduce or inhibit a pilot’s ability to fly an aircraft depending on the level of that exposure.

The AAIB is working with the aircraft and engine manufacturers and the National Transportation Safety Board (NTSB) in the USA to identify possible pathways through which CO might enter the cabin of this type of aircraft. Work is also continuing to investigate pertinent operational, technical, organisational and human factors which might have contributed to the accident.

DaveReidUK 12th Sep 2019 22:50


Originally Posted by Mike Flynn (Post 10568580)
The latest AAIB bulletin featuring this accident is here https://assets.publishing.service.go...019_Lo_Res.pdf

The part of the Bulletin relating to the accident appears to be just a reprint of Special Bulletin S2/2019, published a month ago.


Edward Teach 14th Sep 2019 15:14


Originally Posted by BigEndBob (Post 10558235)
But would it be heard through noise cancelling headphones?

​​​​​​
Definitely. Absolutely 100%.

Mike Flynn 14th Sep 2019 19:46

A large flashing light linked to a carbon monoxide detector might be a better idea.

Duchess_Driver 23rd Sep 2019 14:56

BBC breaking news - pair jailed for the Mortuary Photos of Sala.

cats_five 30th Sep 2019 18:05

Emiliano Sala: Fifa rules Cardiff must pay first instalment of £5.3m to Nantes
https://www.bbc.co.uk/sport/football/49825166

Teddy Robinson 30th Sep 2019 19:25


Originally Posted by cats_five (Post 10583281)
Emiliano Sala: Fifa rules Cardiff must pay first instalment of £5.3m to Nantes
https://www.bbc.co.uk/sport/football/49825166

So what ? this is an aviation forum, not a football forum.

Hadley Rille 30th Sep 2019 20:27


Originally Posted by Teddy Robinson (Post 10583341)
So what ? this is an aviation forum, not a football forum.

A British business being so out of pocket will bring more pressure to bear on scrutiny of the arrangements made for the flight and, by extension, any future arrangements for such flights all of which is entirely aviation related.
Q.E.D.

Mike Flynn 30th Sep 2019 21:29


Originally Posted by Hadley Rille (Post 10583388)
A British business being so out of pocket will bring more pressure to bear on scrutiny of the arrangements made for the flight and, by extension, any future arrangements for such flights all of which is entirely aviation related.
Q.E.D.

As I see it there will be more focus on the grey areas that have existed with jockey flights etc and US registered aircraft operating in the UK but owned by UK residents.

Insurance companies might assess this arena as not worth the risk


ak7274 1st Oct 2019 15:40

I sincerely hope so, but have my doubts.
I suspect the majority of AOC holders have been banging their collective heads against the wall trying to stop this so called and badly named grey charter business.
I sometimes wonder how many Pilots " Don't" know someone who is doing this.

The AvgasDinosaur 1st Oct 2019 16:45


Originally Posted by The AvgasDinosaur (Post 10549493)

I can’t help but wonder why, if all these ‘Air-Grey’ charters are being flown visibly from UK airfields the resident AOC holders have not done so.
Or have they reported them and been ignored ? Several correspondents on here seem to be well aware of what’s been going on.
Has it been reported and ignored or has it just been ignored?
Be lucky
David

Any comments or observations
David


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