It's only for 5 seconds, but that is an awful lot of force. The Falcon system is similar and presumably also involves very high-g forces. Could injury result from the abort itself in either case?
14G sounds like a lot. To put it in context:
- the acceleration you can endure depends on the force vector. The position in which we can withstand G-forces best is forward (using the directions from the XKCD diagram), so spacecraft seats are placed to take advantage of this. When the rocket sits on the pad, the astronauts lie on their back.
- fighter pilots are trained to function at peaks of 9G upward. They use special flight suits to achieve this much. Much higher than that and people lose consciousness.
- we know from tests (John Stapp) that a human can survive peak loads of 45G (backward, or 'eyeballs out') but he suffered vision damage at these loads. People have survived higher loads in car crashes, but injuries are likely.
- untrained humans can survive 20G for 10 seconds.
- fighter pilots who have to eject, experience 12-22G peak loads upward and often have some health problems afterward, and are usually grounded after their second ejection to prevent worse.
- NASA did some research into parachute harnesses. The opening of a parachute also induces a large G-load upward, and they found:
For such harnesses the NASA/AGARD researches indicate a 5% injury risk at 12.1G,
Sitting in a well-designed seat the forces are spread out much better than in a harness. I suspect the injury risk at 14G is pretty low. The crew won't be able to move for those few seconds, but they should be okay.
From the XKCD site:
When I worked with Vladimir Titov on STS-86 he was fine after experiencing such an abort years earlier. If your question is could an injury happen, sure, anything can happen.
EDIT: I had missed that this was about abort, not launch. The answer below has been changed to reflect that.
The G-force estimations here seem to generally be expecting the feet of the crew to be toward the pull. This is not so.
Crew are positioned with their backs to the ground at launch in all spacecraft designs I've ever seen (almost always in the descender part of the craft), specifically because this is the best position from which to resist high G forces.
A few fighter ejection seats are rated for a 14G force, though for lesser duration, with the additional detrimental points that it is a downward directed force and subjects the pilot to windblast (which, if anything kills them, this or a collision is the most likely thing to do it).
With this taken into account, 5 seconds at 14Gs is not pleasant, but its not going to cripple or incapacitate a healthy human, as evidenced by all the healthy folks walking around the planet who have ejected from fighter aircraft. Of course, there may be side effects, but its a lot better than the alternative.