In my job, I travel a lot. Usually on a plane to the other side of the country. Since I started getting serious about bush craft and self reliance, I try to always be prepared for any occurrence and having a few tools always helps, but I also realize I don't have to have every tool in the box as my knowledge and skills develop.
I have been steadily trying to put something together that I can get through security with no problem, but that would help me if needed during an emergency.
My key chain has become an EDC. I have a very small knife that hasn't had a problem getting through security yet, a small fire steel, small pin light and a 4 way whistle (compass, magnifying glass and thermometer). There is also a set of pace beads that I made from paracord.
I usually pack a few other things that I throw into a little bag like duct tape and a bandanna and I plan on adding a few things to make my airline travel kit fairly complete.
Once through security, the key chain goes in my pocket and the other items are at my feet. If we are evacuating I will make every attempt to grab that bag and throw it out in front of me.
Once I add a drum liner inside a zip-lock bag wrapped in about 30 foot of paracord, my kit should be complete.
Knowing more and needing less is always the goal, but if you have some gear, everything is a little bit easier.