@LostInSaigon:
1) Descending to warm air would mean a huge fuel penalty. They only have enough fuel to reach their destination at cruising altitudes. Descending even for a short time would mean they would not have enough fuel to complete the flight
Correct me, if I am wrong, but reaching my destination, would be the least of my worries in that situation.
As far as I have seen the ISIS has the Altimeter included, so not so sure about Stby Altm.
Just my impression......