Iranian president is missing, page-74

Helicopter type is irrelevant but the theoretical service ceiling of a Bell212 or an Mi171 (also used by Raisi) is much the same at around 17,500'

My understanding is the the Bell212 is not pressurised so it's real service ceiling is limited by human endurance so not much above 12000'.

The Mi171 is I understand pressurised but shoot me down if wrong.

I don't have an Iran map in my head but some of Iran's mountains are in the range of 14,000' to 18000' high. Add in the atrocious weather with wild up and downdraughts and mountains waves and you can see the problem emerging.

Or if something mechanical went wrong altitude could be lost in complete blindness with turbulence.

The takeaway is that the helicopter shouldn't have been there in the first place.