If Armageddon leaves Oral Roberts' town unscathed, well, fine. But if it doesn't, American Airlines is ready. This spring the airline opened its supersecure underground computer bunker-a $34 million facility covered with five feet of dirt, built by the airline to be earthquake proof, terrorist proof, flood proof, Sherman tank proof, blackout proof, possum proof, fireproof, tornado proof and generally able to withstand any other type of assault. Computer operations are big business for all airlines, but especially for American, which pioneered their use for reservations. American's Sabre system...