Aircraft positioning using multiple distance measurements and spline prediction

During the crucial phases of take-off, initial climb, approach, and landing where aircraft are close to the ground, Global Navigation Satellite Systems (GNSS) signal strength may not be sufficient to guarantee safe operation, especially in the presence of potential interference, malicious or otherwise, from ground equipment. When the GNSS location is lost, aircraft typically revert to other navigation aids. The most accurate navigation aid is Distance Measuring Equipment (DME). However, whereas GNSS location is triangulated, the navigation equipment on-board aircraft can only measure two DME signals simultaneously. Therefore, location based on DME tends to be accurate only to hundreds of meters, compared to meters for GNSS. A new approach is presented for positioning using multiple DMEs. The approach is based on regression analysis for prediction of DMEs distances in time of measurement. This approach increases positioning accuracy due to availability of multiple DMEs data in the system of navigation equations. Spline functions were used in a regression model in order to achieve the most accurate prediction values. An approach was verified using real flight data and shown the decreasing of navigation system error on value depending on availability and geometry of ground stations locations.