Taking a major step ahead of the U.S., the European Commission (EC) has issued a notice of proposed rulemaking (NPRM) announcing its intent to mandate carriage of automatic dependent surveillance-broadcast (ADS-B) transponders by 2015, versus the FAA’s planned 2020 deadline. The EC also calls for its 27 member nations to align their ATC procedures more closely with those of their neighbors to create a seamless European airspace system that supports five- and three-mile separation standards, for en route and terminal operations, respectively. These initiatives are key elements of the EC’s move towards its Single European Sky (SES) plan and the associated Sesar air traffic management system, similar to the FAA’s NextGen project.

The EC NPRM mandates ADS-B out capability as the initial step to ADS-B in, which will become the standard equipage in future European airspace. The European ADS-B rule is slated to become law late next year (the FAA is aiming for April of the same year), and will confirm 2015 as the date by which all aircraft, both European and non-European, must be ADS-B out compliant. Airplanes weighing less than 12,500 pounds and with cruise speeds below 250 knots will be exempt.

It seems unlikely that the EC’s 2010 rule issuance date will slip (Washington scuttlebutt suggests that possibility for the FAA’s April 2010 date), because the EC has taken a consultative approach in developing the NPRM. Throughout their planning for ADS-B’s introduction, EC officials have involved aircraft operators, Europe’s national ATC service providers, Eurocontrol officials and Sesar representatives in crafting a requirements document that meets the needs of the affected parties. As a result, sources told AIN, the NPRM text, now open for public comment, contains no surprises or contentious technical requirements. After that period closes on April 8, all comments will be published, along with the responses of the EC planning group, and presented for review at a public workshop in May.

The NPRM’s technical specifications are quite similar to the FAA’s. The primary differences are that the EC proposal does not include the U.S. requirement for WAAS–or Europe’s Egnos equivalent–and incorporates GPS performance standards that are somewhat less rigorous.

Nevertheless, there are still some concerns about the European NPRM, although organizations contacted by AIN were reluctant to express these publicly before the comment period closed. For example, some smaller nations anticipate significant costs to achieve the required seamless surveillance continuity with more advanced ATC environments of larger neighboring states. In addition, while Eurocontrol records indicate that more than 40 percent of aircraft are now transmitting ADS-B out signals, the larger proportion have yet to upgrade their transponders, at the EC’s estimated cost of about $80,000 per aircraft. It seems likely that users will request operational or financial incentives–a process used earlier when Europe launched its datalink project.

Also, some suggest that adopting ADS-B out would not significantly improve European air traffic management beyond what is now being achieved with secondary surveillance radar (SSR), and propose the transition should move directly to ADS-B in, which provides situational awareness that enhances safety and will be an essential element in 4-D trajectory flight and other advanced procedures. Others believe that “enshrining” today’s already congested 1030/1090-MHz transponder frequencies into the legislation would further delay the urgent need for a better and more secure surveillance datalink.

The EC’s NPRM takes a pragmatic, “performance-based” approach to achieving the targeted three- and five-mile separation standards. Instead of proposing a continent-wide network of ADS-B ground stations, it recognizes that individual member nations already have investments in SSR and, increasingly, in wide-area and local multilateration networks, all of which can track ADS-B aircraft to three- and five-mile accuracies. Therefore, the NPRM simply states that nations can continue to use their SSR or multilateration systems and, where necessary, deploy them or new ADS-B ground stations to cover airspace not currently compliant.

Like the U.S., Europe plans to decommission many of its 208 SSRs, most of which partially overlap each other’s coverage. In one notable case, AIN was told that no fewer than seven SSRs included the same small area in their surveillance volumes. But total decommissioning is not planned: there will always be “skeleton” coverage to back up ADS-B in the event of, say, GPS outages. Like the FAA, Eurocontrol is studying security issues, such as accidental or deliberate signal interference to GPS and to Europe’s equivalent Galileo satnav system, and to the even more vulnerable ADS-B signals.