On the night of May 19, 1986, Brazilian Air Defense radar tracked 21 unidentified objects moving at estimated Mach 15 across São Paulo, Goiás, Rio de Janeiro, and Minas Gerais. Two F-5Es and three Mirage IIIs were scrambled; pilots reported objects surrounding their aircraft before vanishing. Four days later the Minister of the Air Force held an unprecedented public press conference confirming the events.

Brigadier Octávio Júlio Moreira Lima stated at the May 23 press conference: 'Technically, I'd tell you gentlemen that we have no explanation.' The official FAB report, declassified in September 2009, described the objects as capable of speeds from subsonic to supersonic, hovering, and 90-degree turns. Pilot Captain Viriato pursued one object at 1,350 km/h; it evaded and disappeared from radar. The night became known in Brazil as 'Noite Oficial dos OVNIs.'