While European ATM research focuses on the 2020-oriented Sesar program and the FAA has picked 2025 as the date for implementation of its new system,
private-sector companies are working on near-term improvements.

Mark Viggiano, president of air traffic systems at Sensis of East Syracuse, N.Y., said his company is trying to focus on “transformative infrastructure” that will allow innovations to take place naturally over the years. “The idea of focusing on 2025 is useful,” he agreed, “but anybody who thinks they can look more than five years into the future is probably fooling themselves.”

Viggiano cited the aircraft communications addressing and reporting system (Acars)–“an open-architecture datalink that people have used to do all kinds of remarkable things”–as an example of the sort of innovation he has in mind: “system-wide infrastructure that will allow new people to come up with ideas.”

In Sensis’ case, that means focusing on overlays and additions to ADS-B technology. The company already produces ADS-B and multilateration ground stations operating on both the 1090 MHz mode-S extended squitter (ES) and the universal access transceiver (UAT) frequencies. In fact, it has deployed more than 500 ADS-B transceivers in the U.S., Europe, Asia and Australia. Now, Viggiano said, “We are looking beyond that to add some capabilities that we think will be essential to support evolution over the next 20 years.”

One capability is a secure layer. The idea is first to authenticate the aircraft so the system knows for sure that the pilot and aircraft transmitting are who they say they are in a cryptographically secure way. That is achieved by tying the UAT ADS-B identifier code or mode-S ID code to the flight plan to establish unequivocally “what aircraft it is, who’s flying it and what flight plan he’s flying.” The secure layer also provides the ability to encrypt part of the message so that the aircraft’s identity, position information or both can be concealed, such as for a military aircraft.

The next addition is a transactional datalink that resembles Acars in functionality but offers significantly increased bandwidth. This could use any ADS-B datalink frequency, Viggiano said.

The aim is to facilitate the exchange of flight plan and intent information and negotiate 4-D trajectories. “Because of the nature of aviation you will have to do that repeatedly throughout a flight,” Viggiano commented. “You won’t be able to negotiate a trajectory in advance [and] then fly it. If you don’t get the pushback time, flight level or weather you want you might have to negotiate it repeatedly, and that will be too much workload for pilots if they have to key in the new trajectories.”

ADS-B lowers the cost of surveillance, for ANSPs, but the benefits are not so obvious to aircraft operators. However, one benefit operators will see is the fuel savings that result from better arrival distribution using transactional datalink. There is likely to be some form of preferential service so that aircraft with a transactional datalink with direct interface to the flight management computer (FMC) will gain better access to preferred routing.

Sensis subsidiary Seagull Technology, meanwhile, is working on FMC-flown idle descent/continuous descent procedures that promise all-around benefits. Extensive NASA simulations have verified the capacity gains that result from reduced uncertainty of arrival to a metering fix or runway threshold. An idle descent can save operators several hundred pounds of fuel. And communities on the ground will benefit as well, as constant Mach/constant airspeed descents are much less noisy as well as more fuel efficient than “dive and drive” approaches with engines throttling up and down.

“Precision trajectory approaches can have a great impact on efficiency,” Viggiano added. “Now is the time to be building infrastructure that is flexible enough to allow that kind of innovation. That’s why it is so important to get the infrastructure right now. We see the key infrastructure as being secure ADS-B with a transactional datalink and a standardized interface to the FMC, plus an information network that connects ground and aircraft with a link to the information source,” he concluded.

The ground stations being deployed, including those in the ASDE-X surface surveillance systems being installed at several U.S. airports, exemplify the benefits of this philosophy, Viggiano said, providing high precision and update rate today and with ADS-B functionality built in for when aircraft are equipped.