A flight attendant on the American Airlines plane apparently became suspicious of a male passenger because there was "some confusion as to whether the man was properly security screened" before boarding the London Heathrow Airport-bound flight at Los Angeles International Airport, a law enforcement official said.
Authorities were questioning the passenger Thursday morning at John F. Kennedy International Airport, said the official, who spoke on condition of anonymity because the person was not authorized to speak to the media.
A flight attendant saw the passenger riding on a Los Angeles airport employee shuttle bus from the employee parking lot to the airport employee entrance earlier and then recognized him on the flight after it was en route to London, Homeland Security officials told CBS News.
American Airlines security confirmed the identity of the passenger, the uncertain process by how he boarded the plane and that he was an executive platinum traveler with a legitimate round trip ticket that purchased on April 19, the Homeland Security officials told CBS News.
Homeland Security Secretary Michael Chertoff told CBS' The Early Show the incident may have been a miscue.
Chertoff said it appeared "to be a misunderstanding."
"The good news here, though, is that when members of the air crew saw something which they thought was suspicious they reacted immediately and appropriately," he said.
Chertoff told CNN he heard from the airline that the passenger is an American Airlines employee who was traveling in a private capacity.
Carrying 230 passengers, the flight landed at JFK at about 3:30 a.m., said Alan Hicks, a spokesman for the Port Authority of New York and New Jersey, which operates the airport. He said the agency was told about an hour earlier that Flight 136 was being diverted.
The plane was still at the airport later Thursday morning, Hicks said. He was unsure whether the passengers remained on board or had been allowed into the terminal.