Trial and Error
Take, for instance, the enormous helium balloons in Mexico City. Turns out, the reason they wouldn't fly had to do with the altitude (the city is more than 7,000 feet above sea level). Although Don tried to consult colleagues on this one, he was out of luck. No one had tried this before. "We finally got 'em up there," he says. "We just kept pumping them full of helium."