Yuma Proving Ground Disc Over Test Range 1988

On June 23, 1988, during active live-fire testing operations at the US Army Yuma Proving Ground in Arizona — one of the Army's primary weapons testing facilities — a metallic disc hovered over the test range. US Army test engineers and range safety personnel observed the craft for 20 minutes. The disc's presence directly over an active test range with live fire operations in progress triggered mandatory range safety protocols requiring all test firing to halt while an unknown aircraft was in the range airspace. The disc was stationary for the majority of the 20-minute observation. Optical tracking instruments normally used to track projectile trajectories were slewed to capture imagery of the disc. Army intelligence was notified and an incident report was filed. The Yuma encounter is notable for occurring directly over an active weapons test range — causing actual interruption of Army weapons testing operations — and for the inadvertent capture of imagery by precision range instrumentation.