The Vela Incident (sometimes referred to as the South Atlantic Flash) was an unidentified "double flash" of light that was detected by an American Vela Hotel satellite on September 22, 1979. There is uncertainty as to the true nature of the incident although the U.S. Naval Research Laboratory conducted a comprehensive analysis, including the hydroacoustic data, and issued a 300-page report concluding that there had been a nuclear event near Prince Edward Islands or Antarctica.".

Some specialists who examined the data speculated that the double flash, characteristic of a nuclear explosion, may have been the result of a nuclear weapons test: "The conclusions of the Presidential panel (the Ad Hoc Panel) were reassuring, as they suggested that the most likely explanation of the Vela detection was a meteoroid hitting the satellite — in part because of the discrepancy in bhangmeter readings. Others who examined the data, including the US Defense Intelligence Agency (DIA), the national laboratories, and defense contractors reached a very different conclusion — that the data supported the conclusion that on 22 September 1979, Vela 6911 had detected a nuclear detonation."