This episode's headline: Fright Flights; Lax Labs?; Nicaragua's View. The guests include In Chicago: Dr. GEORGE LUNDERBERG, Journal of American Medical Asso.; In Washingtn; ALLAN McARTOR, Federal Aviation Administration; JOHN O'BRIEN, Air Line Pilots Association; WILLIAM HOOVER, Air Transport Association; JOHN THORNTON, National Air Controllers Asso. REPORTS FROM NEWSHOUR CORRESPONDENTS: KWAME HOLMAN, CHARLES KRAUSE. Byline: In New York: JIM LEHRER, Associate Editor; In Washington: JUDY WOODRUFF, Chief Washington Corresondent