Today, jet noise is affecting many fewer people across the United States than it did 30 years ago.
In the late 1970s, an estimated 7 million people were subjected to high noise levels from aircraft. Even though passenger enplanements have increased significantly since that time, the number of people who experience high noise levels has dropped to fewer than 500,000, according to the FAA’s Office of Environment, Noise Division.
The FAA assesses high noise levels by measuring sound in the neighborhoods around U.S. airports that experience a 24-hour average noise exposure level of 65 decibels (dB) or more. This noise exposure, called DNL or day-night sound level, takes into account the number of aircraft noise events, the noise level of each event, and whether the event occurred in the daytime or at night.
The widespread use of jet engines has helped reduce aircraft noise levels by about 20 dB. Because of the way decibels are calculated, that means airplanes are four times quieter than they were 50 years ago. But as we look at aviation forecasts that predict increasing traffic growth in coming years, we know that noise will continue to increase if we don’t actively work to reduce it.
So, the FAA is hard at work on a variety of solutions to further reduce aviation noise in communities across the country.
Next Generation Air Transportation System (NextGen) technologies and procedures are some of the FAA’s leading tools to help reduce aviation noise. Optimum Profile Descents (OPD), also known as Continuous Descent Arrivals, provide a smooth path to the runway and eliminate the throttle noise produced during the traditional steps-down method, in which the aircraft descends and levels off at increasingly lower altitudes. Required Navigation Performance enables pilots to not only fly OPDs, but also to more precisely maneuver around congested neighborhoods and stay on routes designed to minimize noise.
The FAA and the aviation industry are also collaborating to accelerate the development of mature low-noise technology through the CLEEN initiative (Continuous Lower Energy Emissions and Noise). CLEEN provides incentives to develop improve airframe and engine technology that will reduce noise levels.
Aviation noise exposure less of a problem, says FAA (8/13)
August 13, 2009