Loosen up, nail-biting, sedative popping frequent flyers. Travelling on scheduled United States airlines is safer than it ever has been, with no fatalities in 2002 and only one death in 32.6 million passenger departures in 2003, according to the National Transportation Safety Board, a quasi-independent agency that examines why planes crash and what happens when they do. And even if your plane does go down, the chances that you will walk away from the wreckage have improved sharply in recent years.