The new super airline is all clear for takeoff. A judge approved the merger between American Airlines and US Airways Wednesday, clearing the way for the new combo company to be the largest airline in the world. There was turbulence, however. The judge rejected a proposed $20 million severance package that was set to go to AA CEO Tom Horton, who has agreed to step down within a year. The package would “muddy the water,” the judge said, suggesting that the payout instead be part of the airline’s reorganization plan.