I would imagine that if the plane is traveling at a speed of 510 km/h then this speed would be measured in reference to a point on the Earth, which is rotating. Thus this speed already takes into account the rotation of the Earth.

As far as the circle the plane flies in, yes, we need to add the height of the plane above the surface. So the circumference of such a circle will be

where is the Earth's radius and h is the height of the plane above the Earth.

-Dan