The German Aerospace Center has commissioned an experimental groundstation at Braunschweig-Wolfsburg Airport that makes it possible to carry out satellite-supported precision landings. The final inspection of the Ground Based Augmentation System, manufactured by Thales ATM GmbH, took place on 25 July 2009 following flight-testing with an Air Berlin Boeing 737-700. Air Berlin is the first airline in Europe to trial landings using GBAS stations, in collaboration with the German Air Traffic Control organisation.
The GBAS station at the research airport in Braunschweig will be given the initial task of replicating the functionality of the Instrument Landing System on runway 26. The aim is to create an experimental station that will be used for research purposes, primarily by DLR’s Institute of Flight Guidance.
Demonstration flights for the purpose of commissioning
As part of the flight-testing, the first approach to Braunschweig was carried out as a standard ILS approach, with a subsequent landing. This flight was used to determine the range of the signals emitted by GBAS. After taking off again the aeroplane conducted what is known as a ‘right circuit’, using another standard ILS approach as a basis for comparison. Following the two reference approaches, other approaches were carried out using different configurations of the GBAS equipment.
During the demonstration flights, the ILS approach system was used as a reference for checking the correctness of the information transmitted by GBAS. In addition, the flight trials were used to check the range of the ground station’s correction signals.
Accuracy of position sensing increased to better than one metre
The GBAS station at Braunschweig-Wolfsburg Airport is based on the GPS, which uses satellite signals to allow the exact location of a GPS receiver to be determined. As the capabilities of the GPS system do not meet all the requirements of the various flight phases without an add-on system, ground-supported add-on systems have been developed.
The GBAS station consists of three GPS receivers with their associated antennas, whose positions have been measured precisely and are thus known to the system. During normal operation, the GBAS station receives the GPS signals and determines the offset between the positions as determined by GPS and the known positions. The differences thus determined are sent to the aircraft, which are equipped with a Multi Mode Receiver, twice per second via a Very High Frequency link. In addition, the approach routes that are permitted for the airfield are transferred to the aircraft every 30 seconds.
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