Originally Posted by
EatMyShorts!
Hell, no!! The first point is always to don O2-masks, establish communication and only then initiate the emergency descent. Never the other way around. Never ever.
How long may it take to estabish communication with ATC? 1 minute, easy may be more. With 30 seconds of usable conscience at 30+ thousand feet if things go really wrong with fast dropping cabin altitude that is a Helios 522 recipe. With two pilots, tested O2 system and slow reducing cabin pressure a possible way. But think an Aloha airlines 243 event at 30000. It happened at 24000 feet which is much more survivable if you go down quick. Communicate comes last. You may set 7700 while descending, and then talk to ATC if the descend and O2 is established.
The captain is in command not ATC. In an live threatening emergency all air traffic regulations come in second.