Flight attendants forced their way into the bathroom and discovered the naked passenger at about 3am local time.
Airport police and Federal Bureau of Investigation met the plane when it landed shortly before 3 a.m. Authorities did not release his identity. The flight was carrying 178 passengers to Seattle from Anchorage when the trouble started to begin.
Video footage submitted by a fellow traveler on the flight shows the moment that the entire plane was informed that the plane would be returning to Anchorage.
Speaking to AP, flier Kate Danyluk indicated that she knew something was going on when she noticed the airline staff going up and down the aisles sporting rubber gloves.
"There was a subject on the aircraft that had barricaded or locked himself in the bathroom, the lavatory", airport police Sgt. Darcy Perry told Anchorage television station KTVA.
Federal Bureau of Investigation agents interviewed the naked man back at the airport, Perry said, KTVA reported.
"Flight attendants did find that the subject was naked", Perry said, without elaborating.
Airport police told KTVA-TV they responded to a call around 3 a.m EST from Flight 146 which had taken off but had returned to Ted Stevens Anchorage International airport.
Other passengers on the flight were also interviewed. Flight 146 arrived at Anchorage International around 2:45 am and was met by law enforcement officers at the gate.
"The police came on and took him out the back door", she said, adding that she had heard that the man "had taken off his clothes and he just wasn't in his right mind". The plane was diverted to Anchorage following reports that a man had smeared feces onboard the flight.
In more distressing news, earlier the same day a former Alaska Airlines pilot pleaded guilty to charges of flying a commercial aircraft whilst under the influence of alcohol.
"While no emergency was declared, pilots made the decision to return to Anchorage".