An irate United Airlines passenger knocked out a gate attendant at Washington DC-area airport, hospitalizing the employee and earning himself a one-way ticket to the airline’s blacklist.

A United Airlines gate agent was punched unconscious by a Maryland passenger during boarding at Washington Dulles International Airport late last week, prompting the passenger’s arrest.

A Maryland man has been permanently banned from flying with United Airlines after he suddenly attacked a gate agent at Washington Dulles International Airport on Thursday evening.