Ok, I screwed up in my last posts with respect to the 3rd party - so ignore those - I ended up confusing myself when people began mention 3rd party observers to the scenario - and made a mistake. If the plane is not moving in relation to the 3rd party observer Like in my aircraft scenario) then the plane does not fly. However my aircraft scenario is flawed because there is nothing to prevent the airplane from moving with respect to the gound. Thus the plane to a 3rd party observer could not appear to stay in one spot.

The assumption that the airplane on a conveyor remains staionary with respect to the ground is wrong.

Think about this - carefully.

The conveyor is set up to match the airplanes speed, so if the airplane is moving at 10 mph, so is the conveyor in the exact opposite direction.

The originally scenario does not say that the planes causes the conveyor to move, but that the conveyor is moved by some other control to match speed of the plane.

So if the plane is off of the conveyor on hard ground moving towards the conveyor at 10mph, then the conveyor is still going to move at 10mph in the opposite direction...

Now replace the Airplane with a car (make it a Front wheel driven car) and with the same setup as above, but this time the car drives onto the conveyor.
Once the front wheels of this car touch the conveyor the car stops it's forward motion with respect to the ground - with the front wheels on the conveyor spinning at 10 mph on the conveyor and the rear wheels (which were only spinning because the front wheels were moving along the ground and the rear wheels have to follow) are on the ground stationary.

Now replace the Airplane with another car (make it a 2wd Xterra) and with the same setup as above, what happens when the Xterra drives onto the conveyor? When the front wheels contact the conveyor they (being free spinng) double their speed as they contiune to move up the conveyor until the rear wheels get onto the conveyor. At that point, all 4 sets of wheels are spinning at 10 mph and the Xterra stays in one spot with respect to the ground.

Now, an Airplane has front wheels and rear wheels, so what happens when the airplane moves onto the conveyor?
Does the plane stop it's forward motion when the front wheels touch the conveyor belt? No, the front wheels, which are free spinning, begin to move at 2x the belts speed and the plane continues to move with respect to the ground...
Does the plane stop when all of the wheel are on the conveyor? No, all of the wheels are free spinning so all of the wheels double their speed, the plane continues to move with respect to the ground.