It's apples and oranges to compare cars and planes in this scenario. With a car, the engine drives the WHEELS which are attempting to drive the car forward against the treadmill. With a plane, the engine drives the AIR which in turn pulls (propeller) or pushes (jet engine) the plane through the air while the wheels are spinning freely against the conveyor belt, however fast it chooses to go.

Therefore, it doesn't matter one iota how fast the conveyor is spinning, accelerating, or slowing down... the wheels are not in "gear," they spin freely, so even though they might be spinning at a zillion rpm, the plane's forward momentum is still governed by the thrust of the engine.

Hell, a 747 has enough engine thrust to take off even if its wheels were to fall off...

Why is this so hard for people to get? It's like being at the drag strip and hearing the ignorant masses let out their "BOOOOs" when the jet car fails to do a "burnout." It CAN'T for the same reason that the treadmill is immaterial...

If a regular xterra and an xterra with a jet engine on its roof, each with slick tires, were sitting side by side on an infinite sheet of glare ice; the regular x would sit and spin while the jet x would shoot across the ice like a lightning bolt. Does that help?