Last October and November, a procession of UPS Boeing 767s experimented with a new type of approach to their home base at Louisville International Airport (SDF), Ky. The technique is called the continuous descent approach (CDA). The results of the test flights were released earlier this year and could lead to steeper approach paths nationwide in the name of noise abatement and fuel economy. The tests were conducted by a team of Boeing, the FAA, the Massachusetts Institute of Technology (MIT), NASA, UPS and the Regional Airport Authority, which oversees SDF.

The UPS aircraft and Louisville were chosen because most arrivals are scheduled at night, so the surrounding community was particularly sensitive to noise. Also, the UPS 767s, with their common flight management systems, were considered an ideal fleet, and the tests could be tried out in UPS’ simulators before flying the profile in an actual aircraft.

In the live tests, UPS 767s flew standard approaches and the newly designed CDAs. Fourteen microphones strategically placed on the ground recorded the results. The average noise reduction measured 10 dB, a 50-percent reduction in perceived noise. Because the aircraft were held at higher altitudes for longer periods of time, they burned significantly less fuel. With the results of the tests, the CDA team, led by John-Paul Clarke, associate professor of aeronautics and astronautics at MIT, hopes ATC facilities across the country will be able to adopt new approach paths that reduce noise and conserve fuel.