My air-travel multitool is this one: http://www.leatherman.com/25.html#prefn1=sizecategory&prefv1=Keychain-Size&start=6 . Some TSA checkpoints examine it closely and let it through, others ignore it. It's made about fifty flights with me in 2013 without more than 30 seconds' delay.

Is it as useful as a full-size multi, or the keychain multi I carry when not flying? No. But it's far better than nothing.