So that explained why they had felt free to gain altitude. They had timed their flight plan so as to synchronize it with this jumbo’s takeoff from Taipei airport. It was headed for (she guessed) Vancouver or San Francisco or some other West Coast destination. Cutting underneath it as it vectored northward from the tip of Taiwan, they had positioned themselves beneath it and gained altitude in lockstep with it, their bogey merging with its bogey on the radar screens of air traffic controllers and military installations up and down the eastern coast of Asia.