Oh what a lively discussion here. So I also want to butt in.

Well the plane certainly not going to take off if it's stationary relative to the air around it's wings.

I think a lot of people don't understand how a jet engine works. The enjin just pushes the plane foward. It doesn't pull air over the wings so the air over the wings is faster than the air below it. Thus the engine aren't directly reponsible for the lift. It just moves the plane fowards.

Now such a conveyor belt that can keep a plane stationary probably is impossible to be built. Even if the belt can match the speed of the plane perfectly, since there's friction between the plane wheels and the plane, the plane will just be dragged foward on the conveyor belt once the wheels jam up. What happens after that well, it doesn't matter cause the plane moved.