They started straight away, theres been a few including an Alien Abduction and Malaysia armed forces shooting it down either on purpose or 'acciden't so they're covering it up
They said they found an aeroplane door in the sea, but when they checked it wasn't from this flight. I recall something a few years back when they found a massive part of a jet, from memory it was part of the tail, but had no record of anyone reporting it missing.
Apparently it's now been found to have flown for upto 4 hours after last contact and could be in Pakistan
If it's been hijacked,all it would take for the hijackers to "disappear" with the jet would be to turn its transponder off.... Although why they'd want to disappear with it would be the question obviously. More likely a cabin decompression may have happened,rendering the crew and passengers unconscious and the plane could have flown on its own on autopilot....possibly into the Indian Ocean.
Much more mundane than some of the outlandish speculation I fear. It's crashed into the sea for some reason, as yet unknown, resulting in the deaths of all onboard. Only hope that they knew very little about it and did not suffer. RIP.
Maybe the plane was a Chinese copy made out of Chinese monkey metal, and just disintegrated in mid-air. Or maybe it had rocket boosters which accidentally went off and sent it into hyperdrive cannoning it into a distant galaxy. Or maybe it got sucked up and swallowed by a black hole. Or hit by a meteor. Who knows?