My brother carried a switchblade when he was on flight status with the USAF. As mentioned, it was issued so that he could cut his way out of a potentially deadly situtation -- with his parachute, not with other people. He still has it; it's bright International Orange and looks like a large, two-bladed, ordinary pocketknife (the second blade is a hook with the inside edge sharpened, intended for cutting risers with one hand; it is not automatically opened).