[ILLEGIBLE], December 1952December 1952

On the night of December 4, 1952, First Lieutenant Robert O. Arnold was flying a T-28 trainer aircraft near Laredo Air Force Base in Texas. He was waiting in a holding pattern for permission to land when he spotted a rapidly moving blue light at about 1,500 to 2,000 feet altitude, roughly two miles southeast of the base. Arnold first thought it might be another jet aircraft in the landing pattern, but he quickly noticed it had no position lights or other navigation lights that jets normally display.

The object then climbed to Arnold's altitude of 6,000 feet and began circling the air base in a counter-clockwise orbit. Despite the object's extremely high speed, Arnold attempted to intercept it. As he moved closer, the object descended again to around 1,500 to 2,000 feet and continued circling the city of Laredo, Texas. Arnold described the object's movements as a series of rapid climbs and descents. The entire encounter lasted about seven minutes.

The situation turned dramatic when the object appeared to approach Arnold head-on at high speed. At approximately 100 yards away, the object seemed to veer slightly, as if deciding which side of Arnold's aircraft to pass. It streaked by within about 50 yards of Arnold's left wing. Arnold noted only a blurred reddish-blue haze and could not determine the object's size or shape, though he said it was no larger than his own aircraft. The blue light flickered on and off throughout the encounter, similar to an arc light. After the close pass, the object climbed steeply again and disappeared from sight. Arnold reported the incident to base officials at 2105 (9:05 p.m.).

The Air Force investigation noted that a weather balloon had been scheduled for launch from Lackland Air Force Base at approximately 2100 hours on the same night. The official conclusion, stated in the case file summary, was that the object was probably a balloon. The Air Technical Intelligence Center (ATIC) commented that it believed the object was a conventional aircraft and that the reported maneuvers had likely been exaggerated. However, the main case report emphasized that the object's counter-clockwise orbit direction and southerly heading were consistent with known wind patterns aloft, which supported the balloon hypothesis. The full case file, comprising 12 pages, is reproduced below as held by the National Archives.