[ILLEGIBLE], October 1958October 1958

On the evening of October 9, 1958, a resident of Pleasant Hill, California, observed an unusual object in the night sky at about 9:20 p.m. The witness described it as a hazy bar of orange light, roughly the width of a degree across the sky, with brighter ends than its middle. The object appeared in the west and moved rapidly across the sky at a low angle, executed several sharp turns, and eventually disappeared into the haze above the highway toward Walnut Creek to the southeast. The entire sighting lasted no more than 15 seconds.

The witness noted that the object moved much faster than low-flying aircraft and made no sound. The object's speed, direction changes, steady glow, and lack of a luminous trail convinced the observer it was not a meteor. The sighting was significant enough that the witness wrote to the Weather Bureau at Oakland Airport on October 9 and later completed a detailed Air Force questionnaire in November.

The Air Force conducted a check with the Army Aviation Section and discovered that six H-37 helicopters (a medium-lift transport aircraft with an engine on each side of the fuselage, each driving a single large rotor) were stationed in the San Francisco area. Air Force officials determined that the witness had most likely observed one of these helicopters flying in the area. The helicopters had been in production for approximately three years at the time and were not based at many locations, which the Air Force noted may have made them unfamiliar to local observers.

The full case file is reproduced below as held by the National Archives, comprising 20 pages of original materials.