I carry my rig on the aircraft all the time. You just have to make sure to be ready for a bomb test on the rig after it goes through the xray machine. Also carrying a TSA letter and cypres card also...
Not every culture does, but the many that do are following a custom that goes back to the ancient Romans, who thought a nerve ran directly from the third finger of the left hand to the heart - or so...
I think there is a very subtle difference. hand and hand just refers to two hands not necessarily together.hand in hand implies that the hands are connected or together.