Ninety-eight passengers had boarded São Paulo Airways flight 375 to Rio that morning but the man in seat 3C had a different destination in mind. As the Boeing 737-300 roared off the runway, Raimundo Nonato Alves da Conceição sat quietly clutching a backpack with a box of ammunition and a .32 caliber revolver stashed inside. Enraged by the economic turbulence and hyperinflation convulsing Brazil as it emerged from two decades of military dictatorship in the late 1980s, the jobless 28-year-old had decided to crash a plane into Brasília’s Planalto presidential palace to kill the country’s then leader, José Sarney. “Oh...