Is the FAA asking all of the right questions in its scientific research of aircraft noise?

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The below linked AINonline article identified that FAA Administrator Huerta has initiated an “ambitious project to update the scientific evidence of the relationship between aircraft noise exposure and its impact on communities around airports in today’s context of quieter aircraft, but with more aircraft operations than in the 1980s and1990s and heightened environment awareness,”  March 27, 2015 letter.

The measurement of aircraft noise is a complex science. The current standards, used by the FAA and followed around the globe, are the results of years of multi-disciplined research and analysis. It has been said that hearing is the most subjective of human senses and the academic discipline of psychoacoustics attempts to study and quantify that phenomenon. Scholars have examined the impact of noise from a physiological, engineering (see the above anechoic chamber) and operational perspectives (see the above ATC tracks chart).

With that context as background, what caused the Administrator to write the quoted sentence? On February 15, 2015 a group of 8 trade association CEOs wrote to Mr. Huerta and expressed their joint concerns about a rumored noise project; they said rather pointedly:

“…we are troubled by recent calls for FAA to fiat in new noise metrics and thresholds without basis or to otherwise reverse appropriately adopted advanced Performance-Based Navigation (PBN) flight procedures, such as those recently deployed at Phoenix Sky Harbor International Airport.”

Citing the Aviation Safety and Noise Abatement Act of 1979 (ASNA), the signators reminded the FAA that the statute “established a science-based approach to assessing and addressing noise exposure.”

The March 27 letter, quoted and linked above, speaks for itself:

faa-letter

Hopefully, the response only mentions the survey of airport neighborhoods because it is the first, but not exclusive step in the “methodical approach.” Science is not needed to predict  that this survey will produce numbers demonstrating that the current level of noise is unacceptable to the residents. One would expect that the instrument used in questioning the respondents will capture some of all of the following:

  • the precise location of the residence (to measure distance from the flight track),
  • the date on which the respondent occupied the residence,
  • whether the current ATC pattern existed at the time of the purchase or whether the noise is the result of recent changes to the ATC track,
  • whether the house has sound insulation now
    • whether the insulation was installed before or after the respondent’s purchase of the residence
    • whether the insulation was paid for by FAA/airport funds
    • does the insulation provide any reduction in noise
    • if there is no insulation in the respondent’s house, would the respondent accept free insulation ,
  • whether  there are other noise sources proximate to their residence and what are they
  • how the number assigned by the respondent in the survey compares to other noise sources, such as
    • motorcycles
    • crowd noise at athletic events—at peak, when music is playing, normal cheering
    • ambulances
    • rock and roll concerts

Such questions should provide metrics to assess the respondents’ sensitivities.

As noted above, the survey should not be the sole measure of noise impact. Sophisticated measuring instruments should be used to map out the precise noise being experienced and the results should be able to array the noise by time of day and day of week, month and season, perhaps even weather (low clouds tend to amplify the noise).

The FAA already has the numbers for the noise generated by aircraft in its Part 36 Stage III and IV certification. It also has the ATC track data by aircraft type and air carrier. It would appear to be worthwhile to correlate the certificated noise against the measured noise, aircraft type, carrier and location.

The implication of the Administrator’s ambitious project could result in a lowering of the 65 dBA. Before making such a major alteration of this decisional criterion, it would be wise to measure the economic impacts (i.e. increased FAA funding of insulation) based on this policy decision.

The Administrator has used the term “environmental awareness.” Does this word choice signal that noise policy must be constantly readjusted to meet airport neighbors’ EXPECTATIONS? For example, if a person buys a house in a noise impacted area, it is reasonable for that person to anticipate that this condition will improve? If expectations/awareness becomes the FAA noise target measure, should the FAA also contemporaneously change its Part 36 standards? Should not the FAA, before it moves to such a perspective, be sure that technology can meet the expectations for future noise reductions?

The Administrator’s letter in response to the associations’ inquiry may not have been intended to relate all of the elements of its research. What seems clear is that a phone/paper survey alone would be an inadequate basis for discarding the long-standing 65 dBA.

ARTICLE: FAA To Take New Look at Science of Aircraft Noise

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