Great Idea!
From there on, terrorists only have to break in the central computer, and can steer a much greater number of planes at the same time from the ground!!
You donīt have to find fanatics anymore, who are ready to die, only guys who would be happy with a lot of money, and a capable software, because as soon you have a link from the ground to the flight controls, you have the infrastructure for any kind of software...
Unrealistic? If I told you last week, that the WTC, the pentagon, 4 planes .... and so on...
If it exists, another desaster will happen. And then the whole world will cry out: "We need a big red knob in the cockpit, so the pilots can disengage!!"