Next-gen ATC promises environmental rewards

 - August 27, 2010, 4:40 AM

The benefits of implementing NextGen and its European counterpart, the Single European Sky ATM Research (Sesar), are threefold: not only will the new procedures and technologies improve safety and efficiency, but they will also yield environmental benefits. The ultimate goal is to increase airspace capacity while reducing fuel burn, emissions and noise. 

To that end, the FAA is "moving forward aggressively," according to Michael Romanowski, director of NextGen integration and implementation. "The infrastructure is starting to emerge, and we're seeing a lot of success with early operational demonstrations and deployments." 

The operators involved in transoceanic "gate-to-gate" demonstrations of NextGen capabilities (oceanic trajectory-based operations) are saving significant amounts of fuel, for example. "We're routinely seeing 3- to 5-percent fuel savings per flight," Romanowski said. "On the Atlantic side, we've saved two tons of CO2 per flight. And by saving fuel, you're reducing your environmental impact and seeing a reduction in carbon emissions."

The demonstrations involve not only the FAA and various operators, including American Airlines, Air France, Lufthansa, Qantas and Singapore Airlines, among others, but they also require cooperation from various service providers and agencies. This cooperation will continue into the future, as well. 

In fact, the U.S. and the European Commission on June 18 signed an agreement allowing the FAA and Eurocontrol to work together to provide consistent air traffic service, such as avionics, communication protocols and procedures, and operational methods, to aircraft on transatlantic flights. "The systems will not be identical, but they need to be interoperable," Romanowski said. 

Eurocontrol, meanwhile, recently announced that it has taken "major steps forward" in several key areas of Sesar development. Most important, the agency has cleared the European satellite navigation system, the European Geostationary Overlay Service (Egnos), for final safety certification by the European national supervisory authorities. In collaboration with the FAA, the agency is also moving forward with the aeronautical information exchange model (AIXM-5), the basis for worldwide digital Notams. 

"Gate-to-gate" navigation actually begins long before an airplane leaves the departure gate or begins to taxi. "The FAA is putting a lot of emphasis on being able to make decisions early," said Bruce Carmichael, director of the aviation applications program at the National Center for Atmospheric Research (NCAR). "In fact, it would really like to begin many of the traffic management and flight planning ex ercises as much as 24 hours ahead of time."

Using NextGen technologies and procedures, such as collaborative departure management (CDM), NextGen airports will be able to coordinate traffic on the ground, thereby eliminating takeoff delays and ground holds. ASDE-X is a satellite-based surveillance tracking system that gives operators and air traffic controllers an enhanced view of ground traffic, presented as a color display on a map of the airport. It is scheduled for deployment at 35 U.S. airports by year-end.

Traffic Coordination

CDM, meanwhile, involves collaborative decision making by controllers, operators, airport officials and the FAA, among others, based on common knowledge of the activity on the ground. The concept proved successful during initial demonstration work in Memphis. "Just by sharing information with the operators, and helping them understand what's happening on the ground, they can save 1.5 to 4.5 minutes per flight per aircraft," Romanowski said. "You start seeing dramatic savings in fuel burn and emissions."

This past summer, the Port Authority of New York and New Jersey established a CDM command center to manage traffic flow at JFK while the airport's main 14,572-foot runway was closed for repairs between March and June. 

"In the past, it was not uncommon to see 40 to 80 aircraft lining up for departure," Romanowski said. "Using CDM, [controllers] were able to keep a constant stream of eight to 10 aircraft at the end of the runway. Even with the most significant runway closed, the airport did not experience delays." 

From an environmental standpoint, the experiment was a success: "The Port Authority is estimating that operators are saving five million gallons of fuel per year at JFK," Romanowski said. "It has fundamentally changed how it operates the airport."

In terms of the actual departure, more airports will be using Rnav departures. "With the level of precision they provide, Rnav departures allow us to use runway capacity much more effectively," Romanowski said, adding that Rnav departures have been in place at Dallas/Fort Worth for a number of years. "We've seen a 45-percent delay reduction using Rnav departures. And they save in terms of efficiency and fuel burn, in the amount of $30 million."

Following taxi and takeoff, aircraft will be able to take advantage of NextGen concepts for climb-out and cruise. "The idea with climb and cruise is to be able to do it in a way that's the most fuel efficient for the aircraft," Carmichael said. "To do that requires that all the trajectories for all the aircraft fit together like a jigsaw puzzle."

The system we use today is too reactive, Carmichael said. "It is based on a large number of asynchronous events that happen somewhat independently. We work out the problems when we run into them. We're trying to move away from that, to a more synchronized operation where the pieces of the puzzle fit together just so."

To accomplish this, the FAA will make use of technologies such as automatic dependent surveillance-broadcast (ADS-B) and the traffic management advisor (TMA). Coverage will be nationwide in 2013.

Satellite-based procedures, such as Rnav, can also be used for arrivals. The procedures are being used at Dallas/Fort Worth and Phoenix Sky Harbor International Airport, Romanowski said. "With Rnav arrivals, we're saving 700,000 gallons of fuel per year and 6,700 tons of carbon. And this is just using it part-time [in Dallas]." Phoenix saw a reduction in carbon emissions, estimated at 2,500 tons annually.

Tailored arrivals, in which aircraft use optimized descent paths, are also saving large quantities of fuel. During demonstrations in San Francisco, Los Angeles and Miami, the procedure saved between 100 and 300 gallons of fuel per flight, Romanowski said, adding that the procedure will be operational next year.

The Key to NextGen

Implementing NextGen will also require a change in the way things are currently run, from a human-centered operation to one that is automated and almost completely reliant on technology. "That is an ambitious idea," Carmichael said. "It's not going to be done without a huge culture change, and that's the biggest single impediment to NextGen: it will require a culture change in the cockpit, in operations and in the air navigation services provider."