The RB-47 radar encounter

On 17 July 1957 a six-man Air Force crew flying an RB-47 reported an unidentified object that followed the aircraft for over 700 miles from Mississippi to Oklahoma. The Condon Committee listed the case as unidentified.

On 17 July 1957, a six-officer Air Force RB-47 carrying electronic countermeasures gear flew a route over Mississippi, Louisiana and Texas into Oklahoma. According to James McDonald's 1971 paper, an unidentified object followed it for well over 700 miles across about an hour and a half. The cockpit crew at times saw it as a strongly glowing light, ground radar followed it, and the countermeasures gear aboard detected it.

The Black Vault's account of the Project Blue Book file says that around 4:00 AM, the crew detected a radar signal of unknown origin while over Mississippi. Captain John J. Provenzano, the navigator, and the electronic warfare officers said it resembled ground-based radar but seemed airborne and moving.

The case appears in the Condon Report of 1969. McDonald says the Colorado group lost track of the case files through a date error, and ran its radar and weather analyses for 19 September 1957 in place of 17 July. Their conclusion was that, if the report was accurate, it described an unusual and puzzling phenomenon that "must be listed as unidentified".