In aviation, deadheading is a term used when members of an airline's flight staff are carried free of charge but not working. This most often happens when airline crew are located in the wrong place and need to travel to take up their duties. This is also known as positioning.
The etymology of the expression is unknown, but aviation experts say the term originated "when trains were hauling cattle, if one died enroute, it was known as a dead head (as in "head" of cattle), as opposed to live stock. Trains only got paid for carrying the live ones."[1]
Confidence trickster Frank Abagnale impersonated a pilot and supposedly deadheaded on more than 250 flights.[2]