Wrong, they have a longer PEPT once hypoxic.

They could be less aware of emerging hypoxia because they are more familiar with the symptoms ie. it has become normalised.

I am no expert but know that people who live at 10 k will get used to living on less oxygen and the body compensates by increasing the red corpuscles in the blood
Surely the same would apply to smokers although they have self induced at sea level

On the question of what appears high I think it's what you are used to ? In my 150 days 2000 feet was norm the day I went to 5000 feet I felt very high
Now in a jet 10k feels very low )

Pace

Reading through the various articles my understanding is that this compensation is true if the smoker keeps off the ciggies before flying, if he has a quick one before flying though that is when he will suffer more.

Personally i find that speed comes into the sense of height, 5-10,000ft seems very high in a Moth or Piper Cub at 70Kts but does not seem so high in an A330 at 250kts or even in the RV at 150!

Not long after getting my PPL I was flying with a fellow newbie when I suggested we climb to 10,000ft as we'd never previously been above about 3,000 during training.

Passing 5,000 my companion felt uncomfortable, nothing physical, just not what he was used to so we stopped the climb for a bit until he adjusted then went on up to 10,000, but he really couldn't wait to get down to the lower thousands he was used to.

I quite liked it and will go up there when the mood or the conditions take me. In the Highlands of Scotland it's often the most comfortable place to be provided the cloud base and cover allows.

Delta V

That is strange as I had a similar experience flying with a PPL who was IMC rated and a heavy smoker to Ireland.
The cloud base was 800 feet and I suggested we filed IFR and flew at FL100 in his SEP.
In Solid cloud passing 5000 feet he became uncomfortable and his breathing rate fast.
At FL100 we were in the clear blue above a solid deck of cloud. He kept asking if we could descend to 5000 feet even though that would put us in cloud and lower over the sea.
I told him it was crazy to do so and reaching the IOM the cloud broke up revealing the sea below. seeing the sea he was happy again.
On the return he flew VFR below the then 3000 foot base and was happy as Larry

Pace

High Altitude Airfields
 

Years ago I lived in Quito, Ecuador (SEQM field elevation 9228 MSL) and my third floor (no elevator) apartment was on a hillside around 10,200'. Played tennis at this elevation too. Was flying unpressurized airplanes and helicopters in this area, as well as our base in La Paz, Bolivia (SLLP at 13,323 MSL). One does get acclimated to the low oxygen levels.

Here in Spain in a light aircraft we leave the CTR at 2000 and go up from there with the norm being 7-10,000ft.

Normal transit for me in the Dornier is 15k but higher to 25k if weather requires it.

Chesty Morgan wrote: The paper mentioning PEPT didn't give any evidence to support a beneficial effect of smoking, and the paper you referred to originally (Yoneda and Watanabe) and I was referring to didn't mention PEPT... or in the abstract mention any protective effect of smoking in terms of reducing the impairment due to hypoxia.

You haven't yet posted any links to papers suggesting a protective effect of smoking (though I follow the logic as to why chronic smoking-induced hypoxia could improve performance).

The other thing worth mentioning is that carbon monoxide poisoning largely isn't about hypoxia but about carbon monoxide binding to Cytochrome C Oxidase in the mitochondria (theoretically equivalent levels of hypoxia and Carbon Monoxide levels in terms of reduced oxygen availability have very different prognoses in terms of long-term neurological impairment). How this relates to smoking and flying at altitude I don't know, but it would take a lot to persuade me that smoking is beneficial, and you haven't posted one pertinent article yet.

No, the other one did.

No, the other one did.

Absence of evidence isn't evidence of absence.

Is it beyond the wit of man to collate information from two separate articles?

@ Chesty Morgan:

Your post #42 seemed to be in response to my post #38 which only referenced Yoneda/Watanabe (who don't measure PEPT) so your objection that "Wrong, they have a longer PEPT once hypoxic." confused me.

So the two papers we've discussed so far are:

Comparisons of altitude tolerance and hypoxia symptoms between nonsmokers and habitual smokers. - PubMed - NCBI

Aviat Space Environ Med. 1997 Sep;68(9):807-11.
Comparisons of altitude tolerance and hypoxia symptoms between nonsmokers and habitual smokers.

Yoneda I1, Watanabe Y.

You didn't link directly to this paper, but it's the one cited in the following paper as the source for the statement you cut and pasted.

http://docs.lib.purdue.edu/cgi/viewc...&context=jhpee
Fletcher, James F. "Comparison of Simulated High Altitude Pilot Effective Performance Time Between Habitual Smokers and Non-Smokers." Journal of Human Performance in Extreme Environments 7.2 (2003): 5.

Neither of the above articles mention any beneficial effect of smoking (reduced awareness of the onset of impairment is not a beneficial effect - quite the opposite). Neither show that smokers perform any better in an acute scenario (at least judging by the abstract, which is all I can access). So which is the 'other' article to which you refer?

No, but given that you've posted evidence that smoking harms high altitude performance, and this is the accepted wisdom, then it's reasonable to ask you to put up or shut up before arguing in favour of something potentially very harmful.

Fletcher's paper measures performance after 40 minutes of exposure to a simulated pressure of 10000 feet. Whilst this is different from a sudden decompression/O2 supply failure scenario, if anything it's likely to be more relevant to the majority of pilots on this 'private flying' forum.

One comment I would make about Fletcher's paper is that it used student pilots as subjects who are likely to lie somewhere to the left of this curve showing how lung function changes with age/smoking:

http://static.www.bmj.com/content/bm.../F1.medium.gif

I can see why they did this - though it would have been nice to see the breakdown of their subjects ages. But if they'd used 50 or 60 year old subjects, you might expect things to have looked even worse for the smokers.

Yes, it does appear to be beyond the wit of man.

Back in about 1970, I decided to see how high I could climb in a University of London Air Squadron Chipmunk....

Off from White Waltham, 'Twyford Outbound', turn at Mapledurham and route to the west of Reading, then start the climb when clear of Green One.

Eventually I reached something over 13500 ft, but was getting very cold and rather bored.

But getting down again without the engine getting too cold was far more difficult. A loop with the engine at idle lost some height, but my oxygen depleted condition meant I saw stars over the top....the youthful hangover from the previous night's bar session probably didn't help either :=

So then I went into a descending spiral at around 75º with about 1800 rpm set until I eventually got down to a suitable height to re-enter the free lane at Woodley.

The engineers couldn't understand why the fuel tank fillers were so cold though....

Beagle the spiral is high speed closed throttle not great for cooling )) a spin is better and I believe was a technique used to stay over a relatively fixed point for a cloud break used in the days of poor nav! The spin being slow speed and stable way to descend through cloud!

Pace

Solo spinning was banned at the time, so wasn't an option.

I just set a little below cruise rpm and spiralled down to a lower level at around 90KIAS, then a couple of aeros before RTB'ing.

I would have thought looping at idle would not be that good for cooling either! When I used to drop parachutists i would use a part power spiral to get down without shock cooling the engine.:ok:

Back in my yoof I too once took our Chippy to about 13,000 feet. The last bit took ages, and at that height the aeroplane felt as though it was balanced on a pin - way out of its comfort zone (as was I!). For some reason I felt quite vulnerable looking down from such a height - something I've never experienced before or since in an aeroplane.

I think I slipped off most of the descent. It was a long time ago and memory fades.

Back in 1973 I managed to climb a C150 Aerobat (130hp) to 15500'. The view was fantastic. I was 18 years old and fit.

Of course it was long before the PPL had human factors included so I stupidly chose to spin down to 10,000 and promptly greyed out in the recovery!

I sheepishly landed back at Ipswich very much wiser than when I'd taken off.

Now I will happily operate the Archer up to FL100 if needed but would not want to be up there for the full endurance of the aircraft.

During flight testing of a carburetted Cessna 185 decades ago, I had to clear it for high altitude vapour lock (fuel pumps removed). I took the oxygen, and climbed. I was able to sustain 20,800 feet, with the stall horn screaming at 72MPH indicated, and 12" manifold pressure at full power. I had made it to 21,000, but it would not stay up there.

There was an article in Pilot years ago by someone who took a Turbulent to 20,000' just to see if it could be done. I'd like to re-read that if possible.

Highest in a helicopter for me was in a AS355 at 14,000' in formation with another, the handling and performance were not the best, normally we cruise the jet at FL410-FL420 but that can be quite weight dependant and an auto-pilot walking out could make handling a touch awkward..We practise that in the sim and once a month have a go at doing it manually, the workload is surprisingly high.

I managed 20 500 over Aboyne in a Standard Cirrus glider, took hours for my fingers and toes to thaw out, but the view was stunning.

My favourite was in a Cessna 182 into Leadville Colorado 9927' AMSL, you get a certificate and I've still got the t shirt.

SND

SND

Where the IAS and stall get close together yes you would have to be precise hand flying
With an auto failure at FL 380 it wasn't that hard hand flying a PA28 ( not allowed from other thread to mention Jet so PA 28 ))) if an FO was doing the rest! Maybe a swept wing would be harder

Pace