One moment you're cruising along effortlessly at thirty thousand feet while the cabin crew slosh the whisky around in business class, the next you're in a screaming death-spiral with flames pouring from the hole where the starboard engine was meant to be before some toe-cheese puked a missile up its exhaust. It takes a little time to switch mode from business-as-usual to six-alarms-emergency if you're not primed to expect it,