ATC asking if you have oxygen

every single Corvalis/Columbia (the turbo one) I’ve ever seen was flying at FL100.

…ergo the ones not seen could be at a different level. We normally flight plan the Columbia 400 at +FL180. Never been asked about O2, but ATC (UK, France, Italy, etc.) sometimes query aircraft type.

They were active up to FL160 that day, hence the amusing response. I didn’t mind at all – thought it was funny.

Incidentally, that is the only time I’ve ever not been able to cross that area, yet I know loads of people automatically go round it. There’s no harm in asking… if in fact you even have to ask – a lot of the time, there’s just a recorded message.

It’s quite interesting flying over Salisbury plain. You feel like you’re doing something a little bit naughty and that you shouldn’t really be there. That said, there’s bugger all to see though!

UNL is used in the AIP and is defined simply as “unlimited”.
So that would mean that the restriction applies at any (atmospheric) altitude.

So, unless you can make it into low earth orbit, it might be easier just to go round it.

I think UNL basically means “This (VFR) chart only shows features up to a certain FL (which is listed at the front) and this particular feature exceeds that FL).”

I can’t imagine the ISS having to ask some LARS for a DACS every time their orbit happens to be over that particular DA.

Is UNL higher than FL500 ?

Called up Salisbury for a danger area crossing service a while back and the reply was ‘do you have oxygen?’

It made me chuckle…

I thought you might have been talking about the UK. I participated in a NATStraining day recently and hypoxia, how to recognise it and what to do if you suspect it was a subject they were doing a lot of training on. This in the context of the two hypoxia related fatal accidents in the States recently.