Infx, the plane moves forward relative to the belt and relative to an outside observer.

The conveyor can only push on the bottom of the wheels, causing them to spin. No matter how fast the conveyor goes, it can only spin the wheels.

The plane moves forward by acting on the air, not on the tread.

BTW, if the aircraft goes nowhere, it has no speed. If it does stay in one position, it has NO SPEED and therefore the conveyor would have no speed. The plane accelerates to 10 KIAS (knots indicated airspeed), the conveyor moves in the other direction at 10 knots, the wheels rotate at a rate of 20 knots. The conveyor is powerless to halt or apply equal force to the aircraft because the thrust works to move the entire plane along, while the conveyor can only puch on the bottom of the wheels.

infx, did you read my examples with the skateboard or the aircraft doing a touch-and-go? If the aircraft doing a touch and go would stop on a dime (as your answer indicates) the navy would save billions on carrier suitability testing and you could land anything with wheels on a 200 mile ling conveyor/runway.