As new technologies enable commercial aircraft to fly halfway around the world, industry experts are grappling with the issue of pilot fatigue on ultra-long flights. Delta Air Lines in 2006 implemented its own standards for such flights, requiring two captains and 48 hours of rest, among other things. The FAA used the Delta model in formulating industrywide standards issued last October, but other carriers say that shortcut should be reversed. "We're not challenging the findings of this; it's rather the procedure of the way the FAA went about it," says Tim Smith, a spokesman for American Airlines. The formal rule-making process would result in better standards "because the FAA itself becomes more knowledgeable and better educated through the comment period," he says.