A Back in the early part of the nineteenth century the term dead head (at first two words) was a theatrical term for a person who had been admitted without charge, perhaps because they had performed some service such as putting up a poster advertising the event. ... The verb to dead head followed soon afterwards.

Do pilots still deadhead?

For as long as there have been airline flights or railroad passages or ships sailing the ocean blue, there have been deadheads. As crews move machines about the face of the planet, they frequently find themselves “out of place.” To the airline pilot, deadheading is a fact of life.

What does deadheading mean in airlines?

"Deadhead."

Definition: According to Smith, a pilot or flight attendant who is deadheading onboard a flight is one who is traveling to a destination to be repositioned as part of an on-duty assignment. "This is not the same as commuting to work or engaging in personal travel," he clarified.