W of Phillipsburg, Pa., February 1959February 1959

On the night of February 11, 1959, pilots flying commercial airliners reported seeing a very bright white flash in the sky west of Phillipsburg, Pennsylvania. The flash was about the size of a basketball. After it appeared, the object fell straight down toward the ground, descending slowly. The sighting occurred around 8:42 p.m., and the airliners involved were United Airlines Flight 95, United Airlines Flight 51, and American Airlines Flight 61, all heading east on Airways Victor 188. The pilots reported the flash to be roughly 20 miles north of Phillipsburg.

The Air Force's initial investigation into the sighting was limited. The reporting was incomplete, and officials at the Air Technical Intelligence Center requested additional details from the 26th Air Division. They asked for information about the object's position in the sky when first and last observed, how long it remained visible, the exact location of the observers, their altitude, weather conditions at the time, and whether military night operations were in progress.

To help explain the sighting, Air Force personnel checked with weather stations in the area. The New Cumberland weather service had launched a weather balloon at 7:06 a.m. that morning, which rose to about 22,652 feet. Pittsburgh weather service launched a balloon at 11:23 a.m. that reached about 36,625 feet and traveled northeast. Despite these investigations, the exact cause of the flash remained undetermined. The Air Force's official conclusion on the record card marked the case as "Unknown," though earlier assessments suggested it might have resembled a parachute flare.

The full case file, as reproduced below and held by the National Archives, comprises 13 pages.