Depends on how the body is orientated and how long the exposure is. Also depends on whether youre talking about survival only, or if you want the human to be able to do something. 9 G or thereabouts is pretty much the limit for remaining somewhat functional for a few seconds. But for sheer survival the limit is far higher, and frequently experienced by car crash victims for instance.
During the first cycle to award education points, September 2008, Navy enlisted force stabilization officials noted a slightly larger impact during the advancement cycle than they had anticipated. Of the 89,210 test takers, 2,264 reported a post-secondary degree.
Source: The Role of Education in the Military Promotion Process, RAND Corporation. As a Specialist (E4), you can earn up to 75 points for civilian education, or nearly 10 percent of the possible 800 Army promotion points. For a Sergeant (E5), you can earn up to 100 points, or 12.5 percent of the total possible.