In the crisp, clear air 33,000 ft. over Pennsylvania, United Airlines Pilot Dale Chapman blinked in disbelief. There, one moment, were the myriad lights of Manhattan winking in the distance like diamonds on a jeweler's velvet cloth. An instant later, there was only blackness. "The whole city of New York was missing," marveled Chapman. "It looked like the end of the world."
For Lufthansa Pilot Reinhard Noethel, bringing in a 707 jetliner from Cologne at 39,000 ft., it was the same story—almost. "Ladies and gentlemen," he announced on the intercom, "on the left side...