I would allow time for half of them to escape, as the chance of fucking the lot would be halved (5%, for 1000 crew = 50 lives cost = risk-reward equal). that way we end up with best likely outcome. I'm aware the act of allowing each crew member to escape would shift the risk-return curve, but I don't have time or inclination to plot the exact best number, so I'll go with saving 25 of them before pulling the plug. (yeah, I've done some ops research but its rusty. lol)