I travel by air a fair amount and usually carry-on a backpack with the following:
Ritter PSP
Surefire E2L
Heatsheets blanket
Cell phone charger
Snacks
Reading material
Rain jacket
Atwater Carey LD 1 FAK
Paper matches
A Swedish Mini Firesteel
A cheap key-ring LED flashlight
Hand Sanitizer
and an assortment of detritus that always seems to accumulate when you carry a backpack most every day

Never had a problem with TSA.

My folding knife goes into a checked bag.