Ground Local Elements for Continuity Improvement on Airports
Background & Objectives
The continuous and steady growth of air traffic has led to an escalating number of accidents on airport surfaces. Existing systems for surveillance of ground movements are mostly based on the â€˜see and be seenâ€™ principle to maintain the separation between aircraft and/or vehicles.
These systems have demonstrated their weaknesses in cases of low visibility, resulting in increased ground movement hazards (runway incursions). Today, identified solutions (A-SMGCS Advanced Surfaced Movement Guidance and Control Systems) aim at providing accurate positioning services, based on guidance and communication capabilities. However, these solutions rely on costly surface radars, or on GNSS solutions, which are cheaper but do not operate in satellite shadowing areas. The A-SMGCS solutions aim at providing accurate positioning and surveillance services, based on guidance and communication capabilities.
However, these solutions rely either on costly surface radars or on GNSS solutions, which use satellite navigation systems as basic positioning sensors complemented with EGNOS. These GNSS solutions enable improving the positioning accuracy and integrity, and are cheaper than surface radars (no requested ground infrastructure), have a global coverage and give better performances (EGNOS integrity/accuracy). However, the use of GNSS systems induces continuity and accuracy limitations, due to :
- Complete shadowing effects in areas where GNSS and EGNOS satellites are not visible, leading to an incapacity to localise and to monitor vehicles (inside buildings, hangars, tunnels, etc.);
- Partial shadowing effects, where the visibility configuration of the GNSS satellites induces bad geometric conditions to provide accurate position solutions;
- Multipath effect induced by particular airport environment, such as hangars and aircraft, which are mainly composed of materials with high electromagnetic reflective properties.
The integrated system is based on the integration of the IndoorNav system, which uses WiFi as a positioning system, with the AIRNET system, which uses EGNOS as a positioning system. This overcomes the limitations of GNSS-based systems shadowing effects (continuity issue) and multipath effects (accuracy issue), thus ensuring the continuity of the positioning service in identified critical areas of the airport and therefore ensuring that airport users have the optimal quality of service in all the airport areas. A key factor to success was the definition of an optimal hybridisation scheme and algorithms between the IndoorNav system and the AIRNET system. The hybridisation efficiency was assessed and demonstrated, and the resulting integration costs considered.
The objective of GLECIA was to develop an integrated system based on the integration of the IndoorNav system, which uses WiFi as a positioning system, with the AIRNET system, which uses EGNOS as a positioning system: this ensures the continuity of the positioning service in identified critical areas of the airport. The detailed objectives of the GLECIA project were to:
- Assess the benefits (performance improvements) of integrating the IndoorNav and AIRNET systems;
- Assess methods and develop algorithms for the integration of IndoorNav (hybridisation of IndoorNav and GNSS/EGNOS measurements);
- Develop a demonstrator to illustrate the benefits of the AIRNET/IndoorNav integration in an airport-like environment.
Work performed & results
The GLECIA system enabled validation of the most innovative features of the project and demonstrated that the availability and continuity of the AIRNET positioning service could be improved thanks to the hybridisation with the IndoorNav system. However, because of the limited time frame between the field trials and the project completion, it was not possible to evaluate the improvement on the accuracy of the positioning service. Besides, some limitations were identified, namely interferences between the GNSS receiver and the antennas. These limitations will be carefully addressed if the decision is made to continue with the development of an operational system. GLECIA was therefore an excellent opportunity for the partners to acquire specific knowledge, thus enabling them to further develop the GLECIA concept in other applications.