The deadly crash of a TAM Airlines jet at São Paulo's Congonhas airport on July 17 was just the latest example of the aviation woes plaguing Argentina and Brazil. Over the past year, South America's two largest countries have suffered two deadly accidents and a number of close calls—almost all for a surprising reason. In both states, civil aviation is controlled by the armed forces, which managed to maintain this jurisdiction when the nations returned to democratic rule in the 1980s.

But far from ensuring safer skies, military control has proved fatally flawed—particularly in recent months. Experts say the problem is underfunding and sheer incompetence; neither country's military has the training or resources to upgrade aging infrastructure or cope with the soaring number of commercial flights. "The armed forces aren't constructed to respond to market demands," says William Voss, a retired pilot who now heads the U.S.-based Flight Safety Foundation. "They aren't as quick to respond to incidents and early warning signs that are hallmarks of safety management." And ordinary fliers are paying the price.