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Cardiff City Footballer Feared Missing after aircraft disappeared near Channel Island

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Cardiff City Footballer Feared Missing after aircraft disappeared near Channel Island

Old 22nd Aug 2019, 05:33
  #2041 (permalink)  
 
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Originally Posted by PDR1 View Post
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
Cold you point me to some background on that? My understanding is that, as you say, CO binds very tightly to Hb blocking O2 attachment, but I wasn't aware of any detectable damage to the rbc's themselves. And even if that was the case, I would expect virtually every rbc to be lysed so long post mortem. I had assumed that CO would eventually dissociate from Hb after death because of all the changes that must completely screw-up the Hb molecule. i guess maybe some blood deep in the tissues would be preserved well enough for an analysis?
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Old 22nd Aug 2019, 05:59
  #2042 (permalink)  

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Originally Posted by Laguna123 View Post

My first post as I have had an interest in this from the start and sat and watched what people have been saying.

Maintenance has started to become an issue for obvious reasons.

My understanding is that from what Mr Penney has stated is that the aircraft was due an MOT at the end of the year, so a good guess is December.

So other flights in the said aircraft could have taken place before the fatal night.
i suppose my thoughts are: could this of have been an in flight issue not caused by bad maintenance if the aircraft had clocked up a fair few miles since its MOT. This can certainly happen in a Car even after a few weeks of it passing its Test. failure of parts
Laguna, that is why an aircraft used for public transport is required to be on a regular inspection and maintenance programme, controlled by the authorities. With an aircraft you don't just wait until the "MOT" to see if anything needs doing. An aircraft used on a merely private basis isn't required to be maintained quite so strictly.
Obviously, regular maintenance on an aircraft costs a lot of money.

This is one of the reasons why real professional operators get very upset by amateurs undercutting them on price and therefore on safety. See the posts placed here by SND, for example.
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Old 22nd Aug 2019, 11:09
  #2043 (permalink)  
 
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Originally Posted by double_barrel View Post
Cold you point me to some background on that? My understanding is that, as you say, CO binds very tightly to Hb blocking O2 attachment, but I wasn't aware of any detectable damage to the rbc's themselves. And even if that was the case, I would expect virtually every rbc to be lysed so long post mortem. I had assumed that CO would eventually dissociate from Hb after death because of all the changes that must completely screw-up the Hb molecule. i guess maybe some blood deep in the tissues would be preserved well enough for an analysis?
I was probably a little careless in my choice or words - in this instance by "damaged" I meant that the Hb is permanently put in a state where it cannot transport oxygen - once it has formed CO-Hb i6t is essentially impossible to get it to release the CO and form the O2-Hb which can accept and release oxygen in the "usual" manner, so (in my usage) the Hb is "damaged". There are various ways of determining the propotion of CO-Hb in a blood sample (and indeed in other body fluids) from gas chromatography at the expensive/accurate end to manual spectrometry at the "cheap, time-consuming and reliant on skill" end. But most path labs use an autmated spectrophotometry technique, usually in the form of a specifically designed "CO-oximetry analyser". These machines have proven to be pretty reliable and sufficiently accurate to give a confident post-mortem indication of whether CO-Hb was a cause (or significant contributor) of death.

CO-Hb itself seems to be a remarkably robust and stable molecule which doesn't decay much in normal conditions, and barely decays at all when chilled, so a few days on the sea bed is unlikely to compromise the results significantly. There was a reason why I was aware of all this which I'm afraid I can't go into, but the subject of post-mortem determination of C) poisoning is a well published field because (I understand) CO-poisoning is the most common form of lethal poisoning in the western world. Most of the papers get very technical very quickly, but an easily digestable source would be this one:

https://acutecaretesting.org/en/arti...em-co-oximetry

You may be espcially interested in the section headed "STABILITY OF COHb WHEN MEASURED BY CO-OXIMETRY" (about 2/3ds of the way down) which provides the following:

"A number of studies [23, 27, 28] have addressed the issue of stability of COHb as measured by CO-oximetry in stored blood samples. They have confirmed that COHb is remarkably stable.

No change in CO-oximetrically determined COHb from baseline was noted in postmortem samples collected into heparin and stored for up to 3 years in a refrigerator [28].

Hampson [27] determined that there was no significant change from baseline in COHb for unrefrigerated samples mailed across the US and back again. And Kunsman et al[23] confirmed that stability of CO-oximetrically determined COHb was not dependant on the use of a particular anticoagulant/preservative combination."


HTH,

PDR


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Old 22nd Aug 2019, 12:06
  #2044 (permalink)  
 
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Originally Posted by PDR1 View Post

HTH,

PDR
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.
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Old 22nd Aug 2019, 18:04
  #2045 (permalink)  
 
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Originally Posted by double_barrel View Post
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.
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Old 23rd Aug 2019, 20:21
  #2046 (permalink)  
 
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Originally Posted by nonsense View Post
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.
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Old 24th Aug 2019, 02:53
  #2047 (permalink)  
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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.
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Old 24th Aug 2019, 17:10
  #2048 (permalink)  
 
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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.
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Old 24th Aug 2019, 19:05
  #2049 (permalink)  
 
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Originally Posted by A and C View Post
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 its 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 its 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.




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Old 25th Aug 2019, 08:20
  #2050 (permalink)  
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Originally Posted by PDR1 View Post
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 View Post
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.
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Old 25th Aug 2019, 08:47
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Originally Posted by BFM View Post
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
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Old 25th Aug 2019, 21:22
  #2052 (permalink)  
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Originally Posted by PDR1 View Post
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.
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Old 30th Aug 2019, 21:34
  #2053 (permalink)  
 
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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.

Last edited by BigEndBob; 30th Aug 2019 at 21:48.
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Old 12th Sep 2019, 20:59
  #2054 (permalink)  
 
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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.
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Old 12th Sep 2019, 22:50
  #2055 (permalink)  
 
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Originally Posted by Mike Flynn View Post
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.

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Old 14th Sep 2019, 15:14
  #2056 (permalink)  
 
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Originally Posted by BigEndBob View Post
But would it be heard through noise cancelling headphones?
​​​​​​
Definitely. Absolutely 100%.
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Old 14th Sep 2019, 19:46
  #2057 (permalink)  
 
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A large flashing light linked to a carbon monoxide detector might be a better idea.
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