NEW YORK (AP) — More travelers are flying than ever before, creating a daunting challenge for airlines: keep passengers safe in an ever more crowded airspace. In some areas of the world, there's going to be a learning curve," says Patrick Smith, a commercial airline pilot for 24 years and author of "Cockpit Confidential. Industry experts acknowledge the difficulties, but note that aviation has gone through major growth spurts before and still managed to improve safety along the way. Yet, the chances of dying in a plane crash were much lower. Since 2000, there were less than three fatalities per 10 million passengers, according to an Associated Press analysis of crash data provided by aviation consultancy Ascend. Airplane manufacturer Airbus says that while U.S.