Visitors who arrived at this year’s NBAA Convention on a commercial flight into Atlanta Hartsfield Jackson International Airport might have noticed a much longer glide on the approach and less noise in the cabin. As part of an initiative called AIRE (Atlantic Interoperability Initiative To Reduce Emissions), formally launched at the Paris Air Show in June, the airport has started testing “trajectory-based operations” including continuous-descent approaches (CDAs) aimed at reducing fuel burn, CO2 emissions and noise.

The practice calls for aircraft to begin their descents closer to the airport, with their engines near idle almost all the way to touchdown. Atlanta-based Delta Airlines is a key participant in the testing. Joseph Kolshak, the airline’s vice president of operations, described the procedure as “a no-brainer. It’s essentially flying the airplane the way the airplane wants to be flown,” he said. “Stay up at altitude until such time that you can start a continual descent almost all the way to the runway instead of doing step descents.”

While the procedure is being touted for its green benefits, the airlines are enthusiastic about using CDAs for other reasons. With settings on very low thrust for the landing approach, the normally fuel-thirsty engines will consume less jet-A.
“Reducing fuel burn will reduce our costs, but it will also benefit the environment, and if we–together with air navigation service providers–can establish this, a lot will be [accomplished],” said SAS senior vice president Hans Ollongren, whose airline has been practicing CDAs at Stockholm’s Arlanda Airport.

Substantial Fuel Savings

Those fuel benefits can be substantial, according to Delta’s Kolshak. “The beauty is our beta tests have shown an average savings of about 400 pounds of fuel per flight,” he said. “It equates to about 13 million gallons a year saved. That’s just from Delta, and that’s just [into] Atlanta.”

Delta’s CDA tests have occurred only during less congested times at the normally bustling Hartsfield Jackson International hub. While results have been promising, some people doubt whether CDAs will truly be practical. “To actually implement it in a much higher  density environment would be very challenging,” said Tom Niffalke, the airport’s director of environmental and technical services. “To sequence aircraft not only along one route but from multiple routes that eventually feed into two and then one waypoint, you’ve not only got to maintain that separation, but then you’ve got to sequence the airplanes from different directions. They are just getting started with their research now, and they know these are some of the things they have to tackle,” he said.

Other improvements to help the feasibility of CDAs, such as ADS-B, should come from the FAA’s proposed NextGen air traffic control system, but Kolshak said he is confident about the current level of aircraft readiness. “The technology today is such that the airplanes can do it. I can program my [Boeing] 777 to be over Rome, Georgia, at a particular time, at a particular altitude and at a particular airspeed and it will do it,” he said.

But, he added, this capability is not limited to huge jetliners. “As a matter of fact, the GA guys in many respects have better flight-management equipment. Look at the VLJs that are coming out. I was looking at one of the Embraer airplanes, and it’s got better equipage than any of our airplanes.”