Airline Close Calls Happen Far More Often Than Previously Known::On the afternoon of July 2, a Southwest Airlines pilot had to abort a landing at Louis Armstrong New Orleans International Airport. A Delta Air Lines 737 was preparing to take off on the same runway. The sudden maneuver avoided a possible collision by seconds. Nine days later, in San Francisco, an American Airlines jet was accelerating down the runway at more than 160 mph when it narrowly missed a Frontier Airlines plane whose nose had almost jutted into its path. Moments later, the same thing h