Alerted by a secret coded signal from the 747’s pilot, Air Traffic Controller Jan de Haas was sure that a skyjacking was in progress in the skies over the Netherlands.

Air Traffic Controller Jan de Haas stared grimly at his radar screen in the tower at Amsterdam’s Schiphol Airport: something was terribly wrong with Japan Air Lines Flight 404, which had just taken off for Anchorage en route to Tokyo. Alerted by a secret coded signal from the 747’s pilot,…