Sioux City, IowaJanuary 1951

On January 20, 1951, control tower operators at Sioux City Municipal Airport in Iowa watched a bright light maneuver near their field for approximately fourteen minutes. At nearly the same time, the pilot and copilot of a Mid-Continent Airlines DC-3 transport that had just taken off observed an object with lights that appeared to be between red and orange in color, traveling at an estimated four miles away and 3,000 feet high.

The pilots described coordinated maneuvers with the object. As their plane climbed to the left after takeoff, the object circled in a wider arc. When it reached a point to the east, it blinked lights that resembled normal airplane running lights, though the blinking appeared manually controlled. A single bright light, similar to a landing light, then appeared briefly. As the plane continued circling northward, the object made a sudden ninety-degree turn and descended rapidly at high speed, crossing in front of and above the aircraft before taking up a position approximately two hundred feet off the left wing, flying in loose formation at the same speed. The object remained in this position for two to three seconds, then disappeared below the plane and was not seen again.

The pilots described the object as roughly equivalent to a B-29 or slightly larger, with a fuselage resembling a flattened cigar and a long, slender wing set well forward and straight across. No engine nacelles or tail assembly was visible. The object appeared fully maneuverable, moving at will from high speed down to the plane's 120 mile-per-hour climbing speed, without flutter or oscillation.

Control tower personnel and two air force officers who were passengers on the flight all considered reliable witnesses confirmed aspects of the sighting. Tower operators noted the object hovering near 2,000 feet, then moving to follow the aircraft at altitude. Weather conditions were clear. No conventional aircraft or jets were known to be in the vicinity. The file notes that the detailed description and credibility of the witnesses prevented the report from being easily discredited.

The full case file is reproduced below as held by the National Archives, comprising forty pages of scanned documents.