Sea-Tac Airport's spokesperson Perry Cooper says the man, in his late 20's and likely under the influence of drugs, ran through a security checkpoint and down Concourse D around 8:30 p.m. while TSA and police gave chase.
He then got onto the jetway through a secure door to the airfield, up the stairs of a gangway where he broke the window of a code-locked door and crawled through that window onto the American Airlines plane.
Once in the plane, officers were able to take the man into custody after a struggle. The man was arrested for investigation of trespassing and assaulting an officer.
Cooper said that there were no delays at the airport nor was there a shutdown.
