A man who had missed his flight Wednesday said a bomb was aboard the plane, forcing it to return to Seattle-Tacoma International Airport even though authorities did not believe the threat was legitimate, an airport spokeswoman said.
"The plane was brought back, erring on the side of caution, after he made that threatening statement," Transportation Security Administration spokeswoman Jennifer Peppin said.
No bomb was found, airport spokeswoman Terri-Ann Betancourt said.
The man told a gate agent a bomb was on Northwest Airlines Flight 980 shortly after the plane left Seattle for Memphis about 12:30 p.m., Betancourt said.
He was taken to a holding facility at the airport police department's headquarters.
"After interviewing him, they said they do not believe it was a credible bomb threat," Betancourt said.
The man was never on the plane and had no luggage on the aircraft, Betancourt said. She said the man's motive was unclear.
The plane, an Airbus A320 with 142 passengers and five crew members on board, returned to the airport about 1:15 p.m., Betancourt said.
Passengers remained on the plane for more than an hour while police determined how extensive a security sweep was needed. Everyone was taken off and dogs searched for traces of explosives, Betancourt said.
It is a federal offense to make a threat against a commercial aircraft.