Can I ask how you summon a dead-heading company pilot to the flight deck without alarming passengers? Is it done by using a code over the PA? Or do the cabin crew go through the passenger list? How would they know whether a passenger was also a company pilot? I hope these aren't secret questions that can't be asked - I'm just curious!
Would there not also be a rest issue with a dead-heading pilot? Although I suppose no one would claim they're over FTLs when it comes to an emergency of that scale.
Nick