accidents unit. this is not the first time air traffic control has been called into question. >> reporter: in air transportation, there are no second chances. but there have been a number of close calls and even tragedies that have been cause for alarm. >> jeff blue 171, cleared for takeoff. >> like the case of the controller's kids landing planes at new york's jfk last year. >> adios amigos. >> the controller was put on leave. and an even more disturbing case, the air traffic controller on a personal phone call when he should have been manning his post. a helicopter crashed over the hudson river in 2009 that left nine people dead. and then there's been cases where exhaustation and demands of a nerve-racking job have