TWO YEARS AGO, Malaysia Airlines Flight 370 disappeared somewhere over the Indian Ocean with 239 people on board. What then grew into humanity’s largest, most expensive search operation has also been among its most frustrating and beguiling. Investigators have found only one real bit of evidence, a wing flap that washed up on the shores of Réunion, near Madagascar. It was pretty useless. Because it spent nearly 500 days bobbing around on the ocean’s surface, all it indicates is that the plane crashed into the water. Likely to the east.