The Historical Driver for Next Generation Surveillance
In the late 1990’s, air traffic control systems in the United States and Western Europe began seeing more and more delays. For the first time, EUROCONTROL reported average delays of more than 15 minutes per flight. At that time, slow turning radar technology with update rates up to 12 seconds, some of which were 15-20 years old, together with old and isolated data processing systems, were commonly used around the globe. ATC system procedures simply could not cope with the huge traffic demand created by the liberalization of the airline industry and the prosperous global economy.
The Dawn of Multilateration
Since the beginning of the last century, there have been many external forces that have greatly affected the economics of the aviation industry. We have seen the airline industry change dramatically, by mergers and bankruptcy; we have seen aircraft manufacturers merge into only 2 major companies; and we have seen air navigation service providers (ANSPs) strive for improved efficiency and increased productivity.
One major way that ANSPs have looked to balance the steadily increasing demand in air traffic with the increasing safety demands and lower costs is to look to next generation air traffic management technology. They found that technologies, such as Mode S MSSR radar with higher update rates (4-8s), multilateration for airport and wide area surveillance and multilateration for height monitoring units could serve as significant tools to help them achieve their ambitious goals.
The Pioneers of Multilateration
In the early 2000’s, two ANSPs emerged as surveillance pioneers, and began replacing their radars with multilateration technology. The Czech Republic and the Austrian ANSPs were the first to deploy wide area multilateration (WAM) systemsinstead of radar technology. Ostrava in the Czech Republic (2003) and Innsbruck in Austria (2004) were such great successes, in terms of technical and economical performance, that a whole group of ANSPs in Europe and even the FAA started to look into this new substitute technology. Life cycle cost savings for Innsbruck have been calculated at about 13M Euro (W. Langhans, Ch. Scheiflinger, et.al., 2007), when compared to MSSR, which would have required two systems to adequately cover the extremely mountainous region of the Inn valley.
The successful introduction of these two pioneer WAM systems has triggered a sequence of actions in the industry. EUROCONTROL has established the MLAT-Taskforce, which coordinates the international standardization process and exchange of user and industry information; EUROCAE has started the WG-70 workgroup and has created the technical specification (ED-142) for WAM to support ATC separation services of 3/5NM; and ICAO has integrated MLAT technology into their Annex 10 and Doc 4444. EUROCONTROL has also published a generic safety case and a general approval guideline in order to support civil aviation authorities and ANSPs to introduce the MLAT technology in their areas of responsibility.
Over the last decade, many more ANSPs have taken WAM systems operational, such as the FAA, AENA (Spain), South African ATNS, NAV Canada, Australia, Armenia, Namibia. Even more are currently in the process of deploying them, such as UK NATS, Deutsche Flugsicherung GmbH (DFS), NAV Portugal, LVNL, ROMATSA, Tajikistan and many military organizations.