Aircraft fly from a departure airport to a destination airport along a route that is ideally a great circle connecting the two airports. Weather and other aircraft traffic, along with other considerations, can lead an airplane across a range of territory when flying the route from day to day.
Airplanes inherently favor flying wings-level while not maneuvering (as opposed to a slip.) This leads to greatest passenger satisfaction and can avoid troubling issues with fluids. As a result, the orientation of the airplane changes with respect to satellites operating along the geostationary orbit (GSO). The relative orientation between satellite and antenna leads to beam steering (azimuth, elevation, polarization skew) commands and also has an influence upon the airplane antenna performance.
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| Skew angle and Elevation angle from various satellite positions, flying Los Angeles to Sao Paulo, Multi-gimbal antenna |