Originally Posted by
Discorde
Sod's law would dictate that your pressurisation failure hit you as you were over the New York/ Boston area - 30 degrees left or right ain't gonna help! As you drop your descent will likely trigger TCAS TAs and RAs so now there will be several other aircraft roller-coastering up and down, doubtless triggering further TCAS advisories in yet more aircraft. Would the TCAS systems in the various aircraft be able to coordinate their advisories with multiple conflicts?
Would it not be better to try to get a clearance before you plummet? Or at least announce what you are about to do and wait a few seconds for ATC to acknowledge? Mild hypoxia amongst a few pax is surely a price worth paying to avoid a you-know-what?
Once you have done your 'aviate' which would include immediate descent and a 'navigate' turn away from any conflicting traffic you can see on TCAS, the best thing to do is squawk 7700. Even in busy metroplexes a 7700 will immediately result in controllers turning everyone out of your way. If you are at say FL360 and start descent for 10,000ft that's possibly 4 different sectors as horizontal layers you are dropping through. The coordination the controllers have to do is difficult and all of those sectors are potentially busy and may not respond immediately. However, with 7700 breaking through any filtering and your Mode C winding down fast the information is already there for all the controllers to see and they will react at once. The supervisors are normally automatically alerted and everyone moves to unload the sector(s) that you are in, That is just by you making one selection to 7700.
Ideally, when you have time, you also add to that squawk a Mayday or Pan call telling your current controller what's happening. You are
not requesting a clearance for descent, you are telling the controllers what you
are descending and what you will be doing next. I would expect that any avoidance/deconfliction that a controller would give you would be a heading change you would not be expected to maintain level.