1:34 p.m. local. Carlos Antonio de los Santos Montiel, 23, was flying a Piper PA-24 from Zihuatenejo to Mexico City at about 15,000 feet (4.5 km). While passing over Lake Tequesquitengo, he felt a strange vibration in the plane. Then he saw to the right, pacing alongside, a 10-to 12-foot (3...