Business & GA, Commercial

Performance-Based Communications

By Thomas Kraft | May 1, 2008
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Our air transportation system is becoming increasingly stressed. Fuel costs are rising; we are facing more safety, security and environmental protection requirements. But we also have a variety of technologies to help in the solution. The market is demanding us to accommodate a mixed-capable fleet. Yet we need to maintain civil aviation as a profitable business. Clearly, something needs to be done, and performance-based communications will be a significant part of the solution.

What is performance-based communications? From a very high level, it starts with establishing one or more specifications for Required Communications Performance (RCP) types. These RCP types are associated with the communication capability supporting an air-traffic management (ATM) function such as reducing separation minima — just as we associate an RNAV/RNP type with navigation capability.

When we specify an RCP type, we must consider voice and data communications, and global seamless operations. Therefore, it is important that we specify an RCP type at the global level. Given the problem we are faced with today, it is also important to emphasize that we specify an RCP type from an operational perspective and not based on any particular technology.

The RCP types will be used to assess the viability of emerging technologies and to qualify different parts of the system, such as the aircraft system, the operator’s procedures, the communication services, and the air navigation service provider’s system and procedures. The RCP types also provide the benchmarks for ongoing monitoring of actual operational and technical communication performance.

Communication is and will continue to be fundamental to ATM. Data communication already has met safety needs and has enabled air-ground integration needed for 4-D trajectory operations, a main component of the Next Generation Air Transportation System (NextGen) and Single European Sky ATM Research (SESAR) program. Data communication will reduce gross navigational errors, lateral height deviations and misunderstandings.

But we are experiencing problems with controller-pilot communications and air traffic service inter-facility communications. And the problems are not going away. Communication will not improve unless we place a higher priority on the "C" of communication/navigation/surveillance (CNS) to get the attention needed to resolve the issues, to develop the enabling criteria and to implement the needed changes.

The opportunities are there. There is a significant amount of aircraft capability out there today that is not being used. Granted, some aircraft are highly capable and some not so capable, but a mixed-capable fleet will still be there in the future.

To be viable and operationally practical, we need to base our transition strategies on the "reality" of where we are today and evolve to the "vision" of where we want to be in 2020 and 2025.

Europe and the United States are cooperating on SESAR and NextGen initiatives, but from a communication perspective, what do we see? Europe has an implementing rule in place that will require States and operators to equip with controller-pilot data link communications (CPDLC) based on ICAO’s aeronautical telecommunication network (ATN) technology. By 2015, Europe expects 75 percent of the aircraft to be ATN capable, enabling increases in airspace capacity. The United States is beginning to define the data link service standards for its domestic airspace and intends to provide a globally harmonized data link service to a mixed-capable fleet in 2016.

If we look beyond Europe and the United States, what else is there? We have over a decade of experience in deploying data link infrastructure and equipping aircraft for ATM. Today, operators and air navigation service providers throughout the world are benefiting from CPDLC and automatic dependent surveillance-contract (ADS-C) using the future air navigation system (FANS) 1/A technology. Operators have voluntarily equipped over 2,500 aircraft with FANS 1/A capability and are using it. The operators with these aircraft benefit from the use of CPDLC and ADS-C.

In the Pacific, last January, our Oceanic Air Traffic Control Center at Oakland processed nearly 100,000 uplink messages and more than 250,000 downlink messages. Eighty percent of the aircraft in the South Pacific, 60 percent in the Central Pacific, with 30 percent throughout the entire Pacific ocean are FANS 1/A capable. In parts of the Pacific, the FANS 1/A capability has enabled air navigation service providers to reduce separations and provide user preferred routes, reroutes, and improved weather deviation management.

In the North Atlantic, data link has enabled operators to automatically report their position to the air traffic control facility. Nav Canada reduced communication costs to operators with FANS 1/A or the flight management system waypoint position reporting capabilities by 62 percent. Operators with 50 percent of the fleet are benefiting from these reduced costs.

With this data link capability alone, air navigation service providers have been able to handle increases in airspace capacity to levels above those that were experienced prior to Sept. 11, 2001. The North Atlantic went operational this January with a full FANS 1/A CPDLC capability that provides the controller with an intervention capability to complement the enhanced surveillance using ADS-C.

In recent years, some States have worked with industry and research organizations to investigate a tailored arrival procedure at the Melbourne, Amsterdam, San Francisco, and Miami airports. The tailored arrival procedure will improve efficiency and reduce noise and emissions by eliminating the need for traditional step descents into airports. The controller uses CPDLC to uplink the optimum arrival procedure to the flight crew, who automatically load the procedure into the aircraft’s flight guidance system. The tailored arrival procedure, user preferred routes, and reroutes that we are doing today are the beginnings of 4-D trajectory operations.

There is a problem because the FANS 1/A and ATN are not interoperable and the procedures surrounding the two technologies are not always seamless. This problem is not new and has been studied for over a decade. The FANS 1/A capability is an integrated enhanced CNS package that includes CPDLC, RNAV/RNP and ADS-C. For example, the flight crew can automatically transfer into the aircraft’s flight guidance system, complex route clearances taken from CPDLC uplink messages. The software has been approved for Level C applications to support these types of air traffic operations.

The "pioneer" ATN aircraft (approximately 250 exist today) are not integrated and the Level D software does not support some air traffic operations without procedural mitigation, such as a voice readback. The European implementing rule for data link services will require an upgrade to the pioneer ATN aircraft. Nevertheless, we still need a global technical and operational solution, as well as a viable global transition plan.

In early 2005, operators with pioneer ATN aircraft asked member States from Europe and the North Atlantic, "What would it take to provide data link service to my ATN aircraft in the North Atlantic?" The two regions brought the question to the ICAO Paris office, which held a Data Link Harmonization Symposium in March 2005. Following that symposium, work began to answer that question and develop a data link harmonization strategy. Because this was not just a problem at the North Atlantic/European airspace boundary, the ICAO Paris office solicited the support of ICAO headquarters in Montreal to address a global problem.

Last year, the ICAO Paris office solicited input from member States on a data link harmonization strategy. The strategy indicated that any additional ADS-C or CPDLC implementations should use, without change, the existing FANS 1/A aircraft or Link 2000+ aircraft, or move to the full implementation of an internationally agreed common technical definition (as defined or recognized by ICAO).

The strategy went a step further; it explicitly stated that we should stop partial CPDLC or ADS-C aircraft evolutions, as they promote divergent paths to the detriment of the broader community. Finally, despite the underlying technological issues, we need to stop region-specific procedures and converge on "global" procedures.

ICAO has not finalized the conclusions from that solicitation, and Europe and the United States still need to determine how this strategy may affect NextGen and SESAR initiatives, taking into account economical and political perspectives, and the considerations for aircraft equipage forecasts of the different technologies and intended uses in the different regions.

Each region is developing aircraft equipage strategies that are evolving along different timelines. Europe, the United States, and the North Atlantic see some form of a mandate as the only logical solution. Europe has nearly completed the implementing rule and operators will be mandated to equip aircraft beginning in 2011. The data link definition is based on existing standards for the ATN technology. Air navigation service providers may voluntarily provide data link service to FANS 1/A aircraft. Operators using the FANS 1/A data link capabilities before 2014 are exempt for the lifetime of the airframe.

The North Atlantic is considering a data link mandate for 2015. The mandate is considering a data link definition based on existing standards for the FANS 1/A technology. It’s too early to say if and when the North Atlantic air navigation service providers will provide data link service to ATN aircraft.

The United States is considering a data link mandate for 2016. The mandate is considering a data link definition based on standards that are currently under development by the joint RTCA Special Committee SC-214/EUROCAE Working Group WG-78.

So the question is, "Will these mandates be harmonized or viable from an economical perspective? Will they be practical from an operationally seamless perspective or feasible from a technical interoperability perspective?"

Work has been underway on performance-based communications for at least 10 years, but we have only recently completed standards to support its implementation. ICAO has amended Annexes 6 and 11 to include provisions for RCP, effective last November. The organization completed a draft manual on RCP in September 2005. RTCA and EUROCAE jointly published the latest change to the performance-based standard for data link services in continental airspace last June. This is the standard that Europe is using as the basis for their data link implementing rule. RTCA/EUROCAE also published a new performance-based standard for data link services in oceanic and remote airspace last October.

Currently, the North Atlantic air navigation service providers process approximately 1,200 flights per day, and they are expecting 4-percent annual growth over the next 10 to 15 years. They are planning to use CPDLC and ADS-C to support implementation of more efficient operations.

But in June 2007, the North Atlantic member States had expressed concerns with the use of commercial services, in particular, the Inmarsat classic aero satellite services, which provide the data communications for CPDLC and ADS-C. The concerns are related to the increased use of these services, aging equipment in the primary ground earth stations, and the closure of a number of backup ground earth stations, leaving only four ground earth stations which are owned and operated by separate commercial entities.

To address these concerns, the North Atlantic member States invited industry to join them at special meetings last October and November, and this February, where work had progressed to plan the necessary tasks for communications to support future North Atlantic operations. These tasks are based on ICAO and RTCA/EUROCAE standards to implement performance-based communications using RCP 240 and RCP 400 specifications. The tasks are necessary to ensure that planning and implementation activities requiring improved surveillance and intervention capability using data link services are not severely curtailed.

The North Atlantic is considering RCP 240 and RCP 400 for their planned operations. You can find the specifications for these RCP types in the Report of the North Atlantic Region’s RCP Task Force, from their meeting in February. The North Atlantic has based the specifications on the RTCA/EUROCAE performance-based standard and ICAO’s Manual on RCP.

Currently, the North Atlantic is investigating reduced separations that were not specifically addressed in the performance-based standard, so member States are conducting further assessments to confirm that these RCP types are appropriate for North Atlantic operations.

So while North Atlantic operations may be different from other regions, member States recognize the importance to globally standardize the RCP types. That’s why they are using the RTCA/EUROCAE standards as a basis for their work and are coordinating with ICAO headquarters and other regions of the world.

In the Asia-Pacific Region, we began coordinating the RCP 240 specification with Japan at the Informal Pacific Air Traffic Control Coordinating Group meeting last November. We continued to coordinate with the ICAO Bangkok office and the Informal South Pacific Air Traffic Services Coordinating Group (ISPACG). At their 22nd meeting, held in March in Tahiti, member States of the South Pacific adopted the RCP 240 and RCP 400 specifications defined in the RTCA/EUROCAE standard, as amended by the Report of the North Atlantic Region’s RCP Task Force.

The FAA-sponsored Performance-Based Operations Aviation Rulemaking Committee’s Communications Working Group intends to use RCP 240 to provide the benchmarks for assessing the viability of Iridium data communication for aeronautical safety services.

We need coordination between those working on performance-based communication initiatives and those working on NextGen and SESAR initiatives. We need to ensure that our transition from where we are today to the next step converges to an implementation of an internationally agreed technical definition that supports seamless operations worldwide. Each region needs to consider in their business model the forecasts of different aircraft equipage and capability from neighboring regions. One aspect that we may need to address is the planned use of ADS-C in continental airspace, given the ADS-B initiatives.

In conclusion, I will leave you with a few key points. First, the time couldn’t be better for Europe and the United States to take advantage of the opportunities that are out there. Look at the rest of the world, benefit from the wealth of experience, and mature the NextGen and SESAR "visions" into a clear definition that can be transformed into "reality."

Second, leverage existing aircraft capability, infrastructure, and procedures. Sometimes things can go much quicker if we can adopt or even adapt what we have already done. Other times, all that we may need is a new procedure to take advantage of aircraft capability and infrastructure that already exist.

Third, performance-based standards are complementary to interoperability standards and both are essential to evolve operating concepts and to take advantage of advances in technology.

And finally, and perhaps most important, the aviation community needs to cooperate and commit to implement a viable harmonized data link transition plan that provides a solution that will satisfy aviation needs worldwide.

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