Vanished into the ether.
Assuming wreckage is found, there are quite a few oil field construction type ships with deep water Robotic Vehicles in the S China Sea are which are capable of tying shoe laces at 1000m which could be called up. But as yet after an extensive day's searching both by air and sea search and rescue parties; mysteriously no debris has been sighted, not even a cushion or life jacket so no one knows for sure whether it has been hijacked to some where or vanished. I also note that Sky news stories about emergency beacon tranmissions have also fizzled out and oil slick sightings are perhaps another Red Herring.