The world's longest and largest twin-engine airliner, the Boeing 777-9X, has finally taken to the skies for its maiden flight, offering a ray of hope for the troubled US aviation company following months of grim headlines. After days of abysmal weather, airplane WH-001 took from Paine Field, home of Boeing's wide-body factory, north of Seattle, on Saturday morning. The flight had been postponed twice earlier in the week because of poor conditions, but as the aircraft taxied past the press viewing area ahead of takeoff, a rainbow appeared -- perhaps offering a positive portent. When the moment did finally arrive,...