Flight Testing of Advanced RNP to ILS Autoland with DLR’s A320 Test Aircraft

Kurzfassung

This thesis shows the performance of DLR’s test aircraft A320-ATRA during flight tests of experimental RNP to ILS approaches to Braunschweig-Wolfsburg airport. The purpose of the flight test campaign was to demonstrate the feasibility of advanced procedures including a fixed radius turn onto ILS precision final segments with lengths between one and five nautical miles for autoland operations. Enabled by precise area navigation systems based on satellite navigation, these procedures allow the inclusion of turns with a predictable ground track into the approach phase, thus allowing the construction of more flexible routes in areas with a high traffic density or difficult terrain. Furthermore, more environment-friendly procedures can be created due to shorter approach tracks and the possibility to circumnavigate areas sensitive to noise. During the flight tests, three main areas of interest were investigated: The autoland performance of the ATRA was evaluated in approaches with varying lengths of the final approach segment in order to identify a minimum required length for the autoland capability of the test aircraft. Beyond that, the vertical path generated by the flight management system was assessed with regard to its compliance with the intended flight path for a successful transition to ILS guidance at the end of the turn before the final approach. Additionally, the lateral path following during the transition to localizer guidance was investigated for possible violations of the RNP corridor. The results of the flight tests show that it is possible to perform an automatic landing during all experimental approaches, regardless of the length of the final approach segment. Lateral navigation is precise enough to support operations with high accuracy requirements such as RNP 0.1, although the activation of the approach mode can cause larger deviations as soon as the aircraft enters the localizer service volume. During the flight tests, it was also found that RNP to ILS approaches should be coded with a flight path angle in the navigation database in order to prevent an early descent to the ILS intercept height. Although procedures coded without a flight path angle were successful as well, an undesirable level segment was included into the approach by the flight management system, reducing or neutralizing the benefits with regard to noise pollution and fuel efficiency. However, in consideration of the findings of this flight test campaign, it is possible to safely fly RNP to ILS approaches while maintaining the advantages inherent to these procedures.