read the link, little diagram, Australian base satellite, plane flying away from satellite [can't cut and paste for some reason ] anyway planes flying in the opposite direction, or any direction, still gives the same doppler shift.
Satellites in a stationary orbit, it receives a signal, it's non directional, doppler shift only says coming or going. It sends to the ground station, no direction of travel.
Plane can come from East, West , South or North, same doppler shift to the ground station.
Think I need a few more details of how they got the aircraft position in the first place.
Not saying the data is wrong, just no confirmation that it's right. Jim