huv wrote:
Oxygen may well be a very individual matter, that does not help much because you cannot find your own limits by trial and error. It is just not safe.
I entirely agree. An O2 monitor is a good start, but even with that, if you start seeing the numbers go down, how much less oxygen saturation will you accept, before you decide that you should have been on O2 a while ago – in your now reduced judgement state? While ferrying home a 128RG many years back, I had to hop up to 13,000 feet for 20 minutes to clear high ground in the western United States. I felt fine, and seemed to have accomplished the task safely, though my wife suffered terrible headaches for several days after my doing that to her.
I agree that reaction to lack of O2 is a highly individual thing. About a year ago I did an FAA course with an oxygen depletion chamber (the ones that reduce only the O2 level, not the baro pressure). The chamber was brought to the equivalent of 26.000 ft and we had to perform various tasks. The most interesting takeaway was, that the worst performer was a 26-year old CFI (fit, non-smoker, I know the guy personally) and the best performer was, wait for it – a guy in his late 70s. You really cannot know how a person will react unless said person has been at altitude before and knows his/her reactions. As an aside, on x-country flights (which, leaving the L.A. basin pretty much always involve climbing to 10k+) I carry these one-way O2 bottles.
Hi,
Recently flown from EDMV to LHTL 
at 13000 feet. I used my O2 system. I shoot two photos. You can see the difference with oand without O2. No comment on it. Anytime may happen, that you have to climb above the WX.
Wernvik wrote:
That oxygentank only contains 12 liters of oxygen. That’s around 20 breaths. So in an normal situation it will last for about 1,5min.
@Wernvik it’s not a permanent flow but you push a button only on demand so that it should last considerably longer, especially if you only use it at FL140-FL150 for a short period as intended by the OP, if passengers feel uneasy. Of course I’d invest in a EDS, if I’d fly that high with passengers on a regular basis on longer flights.
I don’t think this idea of “not feeling good – take a sniff of oxygen” is going to work, but I have never tried it 
A headache is the most common manifestation but it takes a long time to arrive and doesn’t go away immediately when you start breathing oxygen.
And, as noted above, the reduction in brain function is not going to be apparent to the subject.
Peter wrote:
the reduction in brain function is not going to be apparent to the subject
…which is less of an issue for the passengers on the backseat 
It would depend on how many braincells you have left
I have merged the “EASA oxygen” thread into the existing oxygen thread.
It is well worth listening again to this clip…
While these guys were somewhere in the upper 200’s, it is worth noting that they didn’t have the faculty to realise what was going on and initiating the descent, even though they realised something was up.
You won’t be like a drunk idiot after 30 mins at FL150, but you won’t be at your full faculties, either. And you will find it hard to tell the difference
I finally got my MH system with an oxygen system and just tried it (on the couch ). Now I have a question: the pressure in the cylinder is around 200 bar / 2900 psi, which is also marked as “full” on the regulator. There is a red region on the regulator starting at around 35 bar / 500 psi. So how long can the cylinder deliver enough oxygen, is it until the pressure falls to these 35 bar? I.e. when is it time to refill it?
