hi·jack /'hī-ˌjak/ vt: to seize possession or control of (a vehicle) from another person by force or threat of force; specif: to seize possession or control of (an aircraft) esp. by forcing the pilot to divert the aircraft to another destination
hijack n
hi·jack·er n
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.