I know someone has said this already, but you do realize that aircraft measure air speed, that is to say speed through the air. The relative motion thing is what is confusing you right now.
Also someone mentioned the higher you go the faster you are traveling. This is somewhat true if you are holding a stationary spot above a rotating sphere. The further you are from the center the faster you are going to maintain that same line to the center. The problem is that is completely unrelated to what the discussion is about and it still is a failure of seeing the relative speed. The atmosphere is moving with the spin of the Earth, for the most part. It is still all relative to ground level though. so if you are on the surface at the equator you are moving relative to the axis of rotation, at 1000 mph. This is ignoring the revolution of the Earth around the Sun and the Revolution of the Sun around the galactic center.
But that is also not something we should be getting off onto right now. Back to what I explained about the train scenario, and yes jroa I use it because it is somewhat valid and i know you have no refutation for it therefore you want to dismiss it. Anyway, the Earth is moving at a constant speed in relation to the rotation. You, the plane, the air are all moving with that rotation. It isn't starting, stopping, drastically accelerating or decelerating. What you "feel" as motion while in a jet, a plane, a car,a train, etc. is the change in velocity. Be it vector (direction) or speed. If you are moving at a constant rate, in the same direction, you will not feel the motion because you are moving with it.
The hovering plane scenario is well, whatever we will go with it. It is hovering above the statue of liberty. From a frame of reference from the surface of the Earth it is sitting still. From a frame of reference that is not moving with the Earth it is moving with the Earth. If it were hovering above the surface, you could walk around on it easily because it is not moving through the air. It is moving with the air. Airplanes, once again, measure speed through the air or over the ground. That is your frame of reference, if it is moving at 1000 mph airspeed, it is moving throught the air at 1000 mph. The air is moving with the Earth therefore if it is moving in the same direction as the rotation of the Earth, then from a frame of reference outside the rotation of the Earth it is moving 2000 mph with the Earth turning under it at 1000 mph. Relative to the Earth it is moving 1000mph. Lets use 500 mph instead for a second time through. plane, flying at 500 mph with the rotation of the Earth, from an observation point outside of the rotation of the Earth is traveling at 1500 mph, from the ground it is 500 mph, the Earth from outside is moving at 1000 mph the plane adds 500 mph equals 1500 mph. From the ground 500 mph because the observation point is moving at 1000 mph with it.