ICAO has for a long time issued the NAT Doc 007 MNPS manual which details planning for NAT operation and contingency procedures. The importants bits are also printed on the Jeppesen NA H/L 1-2 Chart. Anyone who has flown, or intends to fly the NAT area should be familiar. Google and behold.
In short, if on a NAT track you turn perpendicular to the track for your emergency descent, declare emergency and request a clearance to proceed to the nearest suitable airport (which might be SNN, KEF, YQX, YYR, etc). You would probably not continue unpressurized at 10,000 ft to your destination. I definitely would not, and I have been plying the Atlantic for quite a while.
Last edited by oceancrosser; 24th Jul 2011 at 00:50.