[JshWright]

That's 10% for someone who had access to advanced care within a few minutes.

If CPR goes on for more than 10 minutes or so in a non-hypothermic patient (with no other interventions), your chances of survival are basically nil. This is is especially true if you have a limited number of people doing compressions. Effective compressions are extremely hard work, and rescuer fatigue is a huge issue with CPR (we switch every two minutes no matter how 'fine' the person doing compressions claims to be). I doubt you could maintain effective CPR on an aircraft for 30 minutes (I suppose you could get a couple dozen people involved, but that seems unlikely).

If I'm not back in 15 minutes, please stop... At that point enough damage has been done to my brain that I don't want to come back...