Northwest Airlines Flight 327
Northwest Airlines Flight 327 was a June 29, 2004 flight from Detroit Metropolitan Wayne County Airport in Romulus, Michigan to Los Angeles International Airport in Los Angeles, California, on N543US, a Boeing 757-200. The behavior of a group of 13 Syrian musicians, on their way to an engagement in San Diego, was deemed suspicious by at least one passenger, who raised concerns that they were observing a terrorist attack or a dry run test.
Source: Wikipedia — Northwest Airlines Flight 327 (CC BY-SA 4.0)