FAA Noise Impact Assessments
Only Hard Data Matters
A recent study has carefully examined the voices being expressed in response to the FAA’s implementation of NextGen’s new procedures at Washington’s Dulles and National Airports. Eli Dourado and Raymond Russell authored the following quote found in their article entitled Airport Noise NIMBYism: An Empirical Investigation, while at GMU’s Mercatus Center.
“Airport noise policy must strike a reasonable balance between noise abatement and the economic beneﬁts associated with noisy airplane takeoﬀs and landings. However, because the majority of noise complaints come from a small number of loud objectors, there is a danger that this balance has been tilted too far in the direction of noise abatement. We hope that increasing awareness of the lopsided distribution of noise complaints can help promote noise standards that strike an appropriate balance and facilitate the advancement of faster and cheaper commercial ﬂight.”
True to its motto, “bridging the gap between academic ideas and real-world problems,” the authors suggest four possible solutions:
- “One option is for airports to acquire residential land below flight.”
- “A second approach is to make noise standards more severe, creating mandatory retirement of the existing fleet of airplanes.”
- “A third approach is to subsidize and otherwise support the installation of more and better insulation in homes aﬀected by airport noise.”
- “Finally, a noise tax could help to efficiently discourage the production of noise without outright banning it, and revenues could be used to fund insulation programs.”
And they conclude:
“It would be a mistake to allow the preferences of a vocal but minuscule minority of citizens, however sympathetic their circumstances, to impede much-needed improvements in aviation. Airport noise standards are already quite strict, and they create real economic and environmental costs associated with lower aircraft fuel efficiency. While our analysis cannot recommend a precise noise standard, we are concerned that a handful of callers—who contact not only airports but also the FAA and congressional offices—have unduly influenced existing standards. Policymakers should be acutely aware of the distribution of calls before taking further action on airport noise.”
Before discussing the merits of the authors’ public policy statement that the FAA is making its decisions based on that the counting of complainer “votes” or tallying the letters of Members of Congress, it is important to premise this post with the acknowledgement that the FAA’s NextGen, particularly the RNP routes, have created a concentration of noise over specific points and that there is a need for a new metric for such impacts. In fact, the FAA in May, 2015 announced that it is reassessing the scientific methodology it utilizes to objectively assess noise.
[In fairness to the FAA, it is also important to note that the FAA continues its dialogue with the community to record what problems are perceived by the public and where feasible, address them. The final outcome in the Metroplex will be based on the existing environmental standards, not a noise referendum.]
That research will not obviate the benefits of NextGen, but should provide analysis which will quantify the impact of these new more precise flight patterns.
In all of its environmental reviews, the FAA uses a noise standard, which may be improved but which constitutes a sound basis to decide how to minimize the OVERALL noise impact of a different Air Traffic procedure (high and low altitudes).
The FAA has for many years used its Integrated Noise Model as its primary method to measure noise but in an effort to more accurately determine impacts, in May, 2015 it adopted the Aviation Environmental Design Tool (AEDT).
These computer modeling methodologies evaluate aircraft noise impacts in the vicinity of airports. They are based on the algorithm and framework from the SAE AIR 1845 standard, which used noise-power-distance (NPD) data to estimate noise accounting for specific operation mode, thrust setting, and source-receiver geometry, acoustic directivity, and other environmental factors.
Using these scientific techniques the FAA is able to
- accurately assess changes in noise impact resulting from new or extended runways or runway configurations,
- accurately assess changes in noise impact resulting from new traffic demand and fleet mix, and
- evaluate noise impacts from new operational procedures.
The data input into these assessment tools are based on operation forecasts, fleet and flight track assumptions. The numbers are then run through the algorithms are create decisional tools as shown in this example:
The model outputs are then validated by noise measurements taken from precise engineering equipment which are located throughout the test area based on reliable statistical determinations:
The FAA typically develops multiple iterations of the alternative Air Traffic procedures and selects the best options based on purely quantitative measurements (noise numbers, safety of flight and efficiency of the ATC). The multivariate equations used may not include the loci of telephone complaints. Part of the reason why the FAA models do not include such subjective or qualitative factors is the science of psychoacoustics which is the study of sound perception. Hearing is not a purely mechanical phenomenon of wave propagation, but is also a sensory and perceptual event. The term “psychoacoustics”…
…involves cognitive psychology and the effects that personal expectations, prejudices, and predispositions may have on listeners’ responses. For example, many react more negatively to the sound of a motorcycle than a noise of an equal energy level BECAUSE the person hearing its signature resonance equates subconsciously to danger. The expression that one “hears what one wants (or expects) to hear” is apt here.
The FAA and the world’s CAAs use objective criteria to assess noise experienced around airports. The voices of individuals may be the basis for further examination of the data to see if here is any anomaly, but they do not constitute a determinative “vote.”
Can the FAA’s assessment of the particular noise generated by the new more precise AT routes be challenged? Yes, but until there is a new, more realistic measurement of that impact, only hard data will matter to these decision-makers.