The long leg pocket on the left thigh of a US flight suit is designed to carry a knife with a combination U-hook parachute shroud cutter and standard switchblade. I have always heard that the shroud cutter was intended to be left open for immediate use (hence the heavy nylon reinforcement sewn/hidden at the bottom of the pocket to protect the wearer's leg) but I never knew of anyone who did. I was also told that the switchblade portion was designed for one handed use (duh) to include situations such as an inadvertent LPU inflation.
I've seen the knife also just as a shroud cutter without the blade. The one I was issued is the MC-1:http://www.lifesupportintl.com/products ... 6-292.html
I understand that there is now a newer version and production, although when I proposed that our unit begin stocking these again for our newer members, I got the shoulder shrug and they eventually bought Benchmade knives. I would have preferred in keeping with tradition, oh well. Here is the new production:http://www.colonialknifecorp.com/Auto_K ... knife.html
After all that typing, I see they did a nice historical summary here:http://www.colonialknifecorp.com/Milita ... story.html