Bite and Sting Kit: It would kinda' suck to survive a plane crash only to get taken out by a snake bite or some wasps. Don't be that guy.
Death Wish: There once was a crazy man named Maurice Wilson who had a plan to crash a plane on Everest, then climb the rest of the way up... despite not being a pilot or a climber.
Water Purifier: Chances are that when your plane goes down, it won't crash land beside a mountain spring flowing with clean water. A water filter is a must and there are several different shapes and sizes to choose from.