Two U.S. Air Force pilots sighted an unidentified flying object near Lebec on September 5, 1949. The UFO hovered and then shot off without a sound toward the ocean. The Air Force Office of Special Investigations (OSI) dismissed it as a weather balloon launched from Sandberg on the Ridge Route, even though, according to the report, the prevailing weather conditions would have sent a balloon out over the Mojave Desert — in the opposite direction.

OSI was founded in 1948 as a criminal investigative unit of the Air Force. Project Grudge, launched in February 1949, was one in a succession of OSI programs to investigate UFO sightings. It was preceded by Project Sign in 1948 and followed by Project Blue Book in 1952. The latter was terminated in December 1969. Project 10073, which appears on some of these documents, is generally a Project Blue Book number, but these documents predate Project Blue Book. Perhaps it was also used by Project Blue Book's forerunners.

(Initial report.)

Investigation requested by CAPT GORDON T. COLLEY, Base Security Officer. Mather Air Force Base, California. SGT (redacted) and SGT (redacted) stated that while flying in a private aircraft in the vicinity of Lebec, California, they had observed an unconventional type aircraft. Aircraft was described as ovular in shape and constructed of a dull, grey metallic substance, approximately thirty-five (35) feet in diameter. Object rapidly gained altitude to approximately seven thousand (7,000) feet, turned in a sharp left bank, and headed in a southernly direction, climbing gradually, and straight out in the direction of the ocean, approximately over Santa Paula and Ventura. No sign of exhaust or vapor trail, and no sounds were noticeable. Object in sight approximately two (2) minutes before disappearing in the distance. Investigation revealed no other witnesses. Aerial photographs taken of area disclosed unidentifiable objects on the ground. A trip was made to Lebec, Calif., to investigate unidentifiable objects, as illustrated in aerial photographs, at which time these objects were determined not to be connected with unconventional aircraft. Interview with SUBJECTS indicated them to be truthful and dependable and not addicted to narcotics or alcohol. Last physical examinations completed on SUBJECTS indicated no abnormalities; no other physical examinations available. Record and Agency chocks revealed no derogatory information concerning SUBJECTS.