Re: Space Shuttle
Also the comparison between the Shuttle and Soyuz some people are making is a bit silly.
If the Soyuz capsule, or its engines, failed - then the crew are as screwed as any Shuttle crew. Because they're sharing the ship with the fault.
But if the second stage failed to fire on Soyuz, they could separate. Equally a slow failure on the Shuttle's SRBs would mean they could be jettisoned. Although the fact that they can't be shut off / throttled and are firing up til jettison does rather suggest they were unsuitable for manned fliight. Unless both fail in the same way simultaneously, it seems likely that most failures are going to result in such catastrophic g-forces, that the orbiter would also be screwed. But then that's the same for Soyuz, if the the rocket fails by cartwheeling in flight or something.
Basically spaceflight is incredibly dangerous. The only big difference is that the Shuttle's main engines could blow up, and from that there's no escape. But otherwise your options are similar - if the craft survies you abort to a landing, or abort to orbit. It's not like you can jump out of an exploding Soyuz, any more than you could out of a Shuttle. I believe it was optional as to whether crews trained for the parachute escape system - which tells you all you need to know about how useful NASA thought it was...