Perspectives: Airspace Users' Equipage Dilemma

The aviation community has widely endorsed the International Air Transport Association's (IATA's) strategic vision for future air traffic management (ATM). (Visit www.iata.org/whatwedo/infrastructure_strategy1.) Guided by this roadmap, one can identify the airborne capabilities needed to support the new ATM concept (see illustration below). But why does implementing these capabilities take so long?

The problem is twofold: technology overload and indecisive implementation. To achieve global interoperability and harmonization between regions, the aviation industry must agree on the supporting communication, navigation and surveillance (CNS) infrastructure. Unfortunately, we seem unable to do this.

Airlines are increasingly alarmed by the risk of multiple equipage requirements and uncoordinated ground implementation programs. They find it difficult to clearly define their equipage needs. Looking at the following technologies, we can see why operators are alarmed--and confused.

Airborne separation assurance. To many this application is the most promising tool to increase airspace capacity. But the onboard equipage costs for this application cannot be assessed at present. The question of whether one supporting system is sufficient or a diversity of supporting systems is required cannot be answered until the ATM application is considered for certification. Yet considerable proof of this concept's feasibility is required before investment can be decided. The comparatively high cost for this application to satisfy the safety case has to be weighed against the benefits in terms of airspace management and flight efficiency.

Surveillance. Automatic dependent surveillance (ADS) is expected to first complement and then replace voice and radar surveillance services. Three supporting links are being considered: Mode S extended squitter; VHF digital link, Mode 4 (VDL-4); and universal access transceiver (UAT). Mode S is considered to be the global, interoperable ADS broadcast link. Unfortunately however, growing support exists for the two other alternatives.

Navigation. The capabilities of GPS are at last starting to be properly exploited. The introduction of APV/baro-VNAV/GPS approaches--ones with vertical guidance/baro-vertical navigation/GPS--will facilitate vertically guided approaches at airports with insufficient or no ground-based navigational aids. But a strong lobby for additional satellite based augmentation systems (SBAS) could bring significant changes to airborne equipage requirements, with questionable long-term benefits, considering the development of satellite services.

Communication. It was recognized 20 years ago that a packet data communication network is the preferred way to ensure adequate capacity to support the future ATM concept. However, only limited use has been made of the available airborne capability, be it VHF airborne communications addressing and reporting system (ACARS), satcom or high frequency data link (HFDL). Instead there has been much more focus on whether VDL-2, -3 or -4 should be the next data link. The aviation industry needs to learn from the telecommunication industry how to roll out a reliable, cost-effective, globally transparent, interoperable and competitive communication service.

Our present system remains safe; however, we must introduce a new ATM concept. Discussing alternative technologies in many forums wastes time. The value of archaic rules, regulations, procedures and practices should be assessed. A complementary roadmap agreed between air traffic service providers and airspace users is essential to head off the potential proliferation of competing technologies. With required capabilities clearly defined, a realistic CNS/ATM global system roadmap can be developed in coordination with the suppliers. Finally, the relevant organizations and stakeholders representing the aviation industry should start to make an attempt to bring all relevant CNS/ATM activity within a single framework.

This column reflects the personal views of Kors Van Den Boogaard, assistant director, CNS, for the International Air Transport Association.