Here's my scoop as an engineer, it's not possible. We still guide jets around with missiles if they go rogue into another part of the country. If such an aircraft was hijacked by a man, they can't call the nearest OnStar and say to safely guide it. They just do not have the systems in place to do so.

Most aircraft still run on cables, pulleys, and highly reliable computers that are way behind on technology. I say highly reliable considering cars cannot have that newest and the greatest GPU, CPU, and motherboard from Tiger Direct. It has to be reliable since it is carrying human lives, now apply that to an airplane. No, aircraft are not up to date with today's technology of wifi and satellite downlink of high amounts of data to the on-board controls. It is more than likely MH370 was 20+ years old running on the usual fly by cable and pulley system.