What happened
In the early morning of July 17, 1957, an RB-47H from Forbes Air Force Base in Kansas, equipped to monitor radar signals, was on a training flight over the Gulf of Mexico and the southern United States. At around 4:10 a.m., over Mississippi, the operators picked up a signal resembling a ground radar, which, however, was moving around the aircraft. Soon the pilots saw a huge bluish-white light crossing their course. For the next hour and a half, over Louisiana and Texas, the light and the signal appeared and disappeared, and a ground radar in the Dallas area tracked a target following the plane. When the crew tried to close in, the object leaped away. Project Blue Book classified the event as unidentified.
Witnesses
The six-man crew of the RB-47H from the 55th Strategic Reconnaissance Wing and the operators of a ground radar station in Texas.
Explanations and hypotheses
Physicist James McDonald considered this case one of the strongest in history because it combines visual observation with detection by two independent systems. Skeptics, including Philip Klass, argued that the first light may have been a fireball and the signal an emission from a ground radar that the operators mislocated. Researcher Brad Sparks and others later concluded that some of the observations may have involved an airliner. There is no final resolution.
Disputed A likely explanation exists, but some of the facts are still disputed.