Over the years, a number of systems have been trialled, including flying trapezes for astronauts to swing away from the pad and the "traditional" launch escape rocket.

The best safety systems offer additional abort modes during launch as well as on-pad, but impose a significant weight penalty that never does anything useful.

The cheapest (in terms of weight penalty) offer on-pad escape only.

What I haven't seen discussed is some sort of crane or catapult that is pad (tower) mounted and would catapult the whole capsule off the top of the stack in the event of a pad emergency.

The capsule would have to seperate from the stack cleanly, be pulled up and away, and deploy its landing parachutes instantly, but might still reach a safe distance from the pad.

Alternatively, some system where a launch escape rocket could add to third stage boost, or whatever, would not be such a dead-weight penalty. Perhaps this would need to be mounted under the capsule rather than above it. (Would the same rocket pack that serves at retros for re-entry be impulsive enough to serve as launch escape?)