The promise of ADS-B is well known by now: provide quality surveillance at a lower cost than conventional radar and improve situational awareness in the cockpit, thereby reducing the number of accidents or incidents–such as runway incursions–in the air and on the ground.

In Europe, Eurocontrol’s Cascade program aims to reduce ATC delays, increase safety and improve ATM efficiency by introducing ADS-B applications and an advanced set of controller pilot datalink communications (CPDLC) services. The main operational benefit of ADS-B, for European pilots and controllers too, is enhanced situational awareness.

However, a recent ADS-B workshop organized at the European ATM agency underscored that there is much work to be done in terms of standardization, implementation and equipment before the system can be widely adopted.
ADS-B implementation will be included in the Sesar master plan, with an initial operational capability next year for ground surveillance applications (ads-b out) and in 2011 for airborne applications (ads-b in). Controllers will continue to be kept in the loop long before pilots will be able to establish any spacing capability. GNSS will effectively be the only compliant position source. However, GPS engines will need to provide the integrity-related information to the transponder.

Six applications will be based on ADS-B, explained Stephen O’Flynn, Cascade operational expert at Eurocontrol. Three applications will be of the ads-b out type and will provide ground surveillance either in the non-radar environment (NRA) for low-density traffic areas or in a radar environment (RAD) for a better quality of surveillance in the periphery of high-density areas as well as surface surveillance at airports to provide better access to airspace, reduce delays, help search-and-rescue missions and improve traffic information service. Atlas in Australia and Girona in Italy are two examples of airport applications.

Airborne surveillance applications will include airborne traffic situational awareness (ATSA), which will require the use of CDTI to display nearby traffic (position, altitude, orientation, aircraft identifier); visual separation on approach (VSA), which could be important for wake vortex situations; and situational awareness on the surface (SURF).

Eurocontrol does not foresee any mandate at this stage however, as long as the efficiency of the program does not depend on 100-percent fleet equipage, said Cascade program Alex Wandels. This could be the case for applications based on ads-b in and TIS-B.

Regarding the potential risks of “spoofing”–the alleged vulnerability of the system to hackers who could invent nonexistent targets and make them appear on pilots’ and controllers’ displays–Eurocontrol officials remain confident.

“A comprehensive security case for ads-b out is planned to be published this year in Europe. In Europe we intend to keep a list of 24-bit addresses that have operational approval. Any incoming signal will be compared to that list before it is used for display to controllers. Also, most processing systems in Europe require that a target appears where it is expected to appear according to its flight plan or that it has been activated by a message from a neighboring control center. In short, spoofing may not be as easy as some people would like us to believe,” Wandels told AIN.

Swedish Experience
In Sweden, national ATS provider LFV has recently released its final report on the EGOA (enhanced general aviation operations by ADS-B) project, which will implement and validate a surveillance tool in the Östgöta TMA, busy airspace where gliders, parachutes, balloons and airplanes from flight schools are flying (see www. egoa.se). Furthermore, Sweden’s regional advanced ATM program (Ramp), due to start this month, calls for use of ADS-B for general aviation operations.
The EGOA project has verified that en route coverage as well as low-level and airport surface coverage can be achieved over a large area with ADS-B at a significantly lower infrastructure cost than with conventional SSR and surface movement radar (SMR).

The prevalent view among pilots is that being allowed to use ADS-B operationally will enhance both safety and situational awareness. Navigational errors would decrease, too, if pilots are allowed to use the moving-map feature of the CDTI. The risk of midair collision or runway incursion will also decrease significantly when other aircraft and airport vehicles are displayed on the CDTI. Most pilots, however, view the current solution with a PDA as the hardware platform as inadequate for cockpit use.
“GA wants early implementation of ads-b (in/out) to reap the benefits and the improved safety that are possible with the available technology today,” emphasized IAOPA’s Klaus-Peter Sternemann. IAOPA favors VDL Mode 4 since the technology has been operationally tested and satisfies most requirements for improved surveillance and new traffic/met services. VDL Mode 4 will be the standard means of navcom in Scandinavia and possibly in Russia and the CIS.

Incentives for GA pilots to equip could come in the form of bundles of services and technology provided by some avionics suppliers such as they did for Capstone, offering mode-S/1090ES combined products.