Ah .. that woke them up
Peekay4 : I agree completely - inappropriate for him to say it, but not inappropriate to think it.
As for service ceiling, not sure where that comes into it.
Unless the crew and passengers are all running on oxygen.
Normal assigned altitude for these flights is 7 - 8000 feet.
And stay well clear of that range of mountains; because you don't need to go that way.
Was PAX on a Merpati Otter when we did a single engine turn-back to UPG in that very region in the early 80's.
From 8000 we lost 2500 in the turn and got about 500 back.
I'll stand by my statement, IF that aircraft is really where it has been reported to be, then it's no place for an Otter, at least not while there are better alternatives.