Project Blue Book Case #2105. On September 17, 1952, witnesses in Tucson, Arizona, observed a silvery, oval-shaped object performing unusual maneuvers in the clear desert sky. The object was visible in broad daylight, its metallic surface reflecting sunlight as it moved through a series of turns and altitude changes that defied conventional aerodynamics.
Tucson in 1952 was surrounded by significant military infrastructure. Davis-Monthan Air Force Base, home to Strategic Air Command bomber units, was located on the city's southeastern edge. The nearby White Sands Proving Ground in New Mexico and various test ranges across the Arizona desert meant that military aircraft of all types were common in the area's skies. Witnesses who could differentiate this object from the usual parade of military aviation carried particular credibility.
The object's oval or elliptical shape was distinct from any known aircraft type. It appeared solid and three-dimensional, ruling out atmospheric optical effects. Its movements included abrupt changes in direction without banking — a key distinguishing characteristic noted in many Blue Book unknowns — and acceleration rates that appeared to exceed human physiological tolerances.
Investigators at Davis-Monthan provided flight logs confirming no military aircraft were in the area matching the object's described position and behavior. Weather balloon launches were checked and eliminated. The desert atmosphere, while prone to mirages at ground level, does not produce the type of high-altitude, solid-appearing object described by the witnesses. Case #2105 was classified "Unknown."