In short, it's an accident that's about to happen, past the point of no return.
Fixed that for you Don.
Nope, I had it right. The accident hasn't occurred yet, but it's going to and nothing can stop it short of a miracle. The accident isn't past the point of no return, because the accident hasn't yet occurred. But it's about to happen - and that pregnant moment is what's past the point of no return. It can't be undone, there's no aborting it, it's inevitable. But it's not quite here yet. Imagine it's just a second before midnight on New Year's Eve - the countdown is taking place, you can't stop the moment from occurring, but it's not here yet.
It's the kind of moment that would appear in a movie in slow motion, dragged out over several seconds, perhaps longer - in reality it's not more than an instant, less time then you'd need to exhale, but in that movie, it's building the suspense. Something in you may be hoping that some kind of intervention takes place, but no, there's no way to stop what will soon become a chain reaction of disaster.