Accuracy and Availability of an Optical Positioning System for Aircraft Landing

Aircraft navigation systems must provide a high level of accuracy and availability, especially during the final approach and landing, which are the most critical phases of a flight. In this work a complementary optical positioning system is introduced which can help to meet these requirements. The system provides an additional source for positioning information relative to the runway. Position calculation is based on detected point and line correspondences between the actual runway and its appearance in the image For establishing of correspondences the runway must be detected. This is done using model-based object recognition methods. An estimation of the expected runway is projected to the image using algorithms of projective geometry. Several criteria are derived from the projected runway, which are used in a downstream filtering process in order to identify those features within the image which represent the runway. Prior to the filtering the features are extracted from the image using common methods of computer vision. The system was installed on board of the research aircraft Dornier Do 128-6 and evaluated in flight experiments, which took place at different airports in Germany.