So it was either diverted to an isolated airfield which would need:
- An isolated airfield with the associated workers to all remain quiet
- The crew on board to be in on it. Or the passengers that were hijackers to be so good at hijacking that they could seize the plane without a whisper leaking out
- Multiple countries faking or losing radar data
- Inmarsat faking their data, then releasing it to let everyone see how clever they were at faking it
- All the countries the plane overflew not seeing anything
- A way to get rid of a few hundred bodies
- A way to hide a large aircraft
- And most importantly, a reason for hijacking the plane and then not making any demands whatsoever
Or possibly a single person (pilot / co-pilot) diverted it to the middle of the ocean in a suicide bid.
Yep the hijacking by the black helicopter brigade sounds far more plausible.