I have to assemble a personal survival kit for myself for emergency situations. The kit has to be on my person at all times during flight. That way it is properly "secured" and can't be lost in a crash scenerio. The kit has to fit in one of my cargo pockets on my flight suit. Most likely I will be using one of the lower leg pockets. So space is very limited.
Some recommendations are:

signal mirror
fire starting device, bic, matches, magnesium, etc.
emergency space blanket/bivy
knife or multi-tool
cordage
asprin, tylenol, ibuprofen
ring saw
bandaids, gauze
duct tape
tube tent?

Usually there is a crew of 3 and everybody carries their own. But there is a master "survival kit" stowed in the rear of the aircraft. It has 2 tarps, 3 blankets, whisperlite stove, 4 cup pot, MRE's, small bow saw, candles, parachute cord, signal mirror, katadyne water filter and a few other things I can't remember. In a worst case situation (crash) this kit could be destroyed, burned up, or inaccessable. Hence, the reason for each person to have a smaller extreme necessities kit on his or her person.

The area I fly in is the pacific northwest and is comprised of rugged landscape, mountains, and desert. The kit needs to be lightweight, versatile, and small. The things everybody in here knows best. So let me know about products you like or any other suggestions you might have. Thanks,

Doug