Stage 5 is coming, but aviation needs to manage expectations of the noise reduction

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Artist depiction of what future aircraft designs might look like

  Good news: quieter airplanes are coming

 BAD NEWS: lower noise will NOT be coming in 2018

FAA Rule Says New Aircraft Design Must be Quieter in 2018

The writer in this avionics article explains what he interprets the new FAA noise regulation means:

“The FAA said it will require newly designed aircraft have lower noise volumes, starting Jan. 1, 2018. A new rule, ‘Stage 5 Airplane Noise Standards,would demand that the latest noise-reduction technology available be incorporated into new designs.”

A result of the new rule, the FAA said, is that new airplane type designs in the subsonic jet airplanes and subsonic transport category large airplanes would operate at least seven decibels quieter than airplanes in the current fleet.

The measurement of human reaction to noise is called psychoacoustics . Sound is the most subjective of the human senses. Scientists and engineers have quantified the reaction of an ear to the noise of an airplane in decibels. With that logarithmic scale, a psychoacoustician issues precise estimates to the population’s response to a plane. Their numbers are expressed in tenths

In that hearing is so subjective, raising or lowering expectations can result in auditory responses that are higher or lower than the mathematical projections of the reactions.

The average citizen reading that aircraft noise in 2018 MUST be quieter is likely to look for reduced annoyance next year. The article’s title and even the FAA press release (New Quieter Aircraft) will likely cause airport neighbors to plan to enjoy quiet title to their homes in months.

The new rule does not support such positive outlook.  The standard WILL BE applied to applications for a new commercial aircraft (a maximum certificated takeoff weight of 121,254 pounds (55,000 kg)) Type Certificate for a new plane starting in 2018.

 

In plain English (excuse the bad pun) that means that Company A will begin to submit documents proving that a new design submitted in 2018 is airworthy. Optimistically that means that this new aircraft will begin to fly in 18 months to three years later than the application is filed. So, in 2020 or so, A (the 1st one) new Stage 5 airliner will be added to the fleet. Assuming that market conditions are positive and that Company A has a great sales organization, this NEW GREEN BIRD will grow to be a 10 or 20% of the US fleet no earlier than 2025. The gradual increase of the Stage 5 airplanes will eventually produce the nice noise reduction shown in the above figure.

 

This rule does not mandate the retirement of Stage 4 or 3 noise level airplanes (several years ago the technology required to achieve those standards required billions of dollars of research and development). The FAA and Congress would have a difficult time declaring such a massive investment in the fleet.

 

Another point about expectations—most of the public cannot decipher the difference between an A320neo and a B-737-100 although there are dramatically different performances in terms of fuel burn and emissions. As the Stage 5 fleet is introduces, it might be wise to require that the engines or the belly of the new plane be painted in green.

 

The FAA’s press release includes another conundrum:

“In 1975, there were about 200 million people flying in the United States, with about 7 million people exposed to what is considered significant aircraft noise.  Since then, an FAA study conducted in 2015 showed that the number of people flying in the United States had almost quadrupled yet the number of people exposed to aircraft noise had dropped to around 340,000, or a 94% reduction in aircraft noise exposure. “

The writer of this factually correct two sentences must not have access to the thousands of angry articles all over the country complaining vociferously about NOISE. Yes, the FAA and industry have devoted time, technology, capital and creativity to reduce noise, but the public’s perception is not that there has been a 94% reduction.

Recent research may have discerned some correlation between certain sounds and “noise rage.” The phenomenon is called misophonia[1], literally “hatred of sound.”

In 2000 scientists defined misophonia as a “condition in which negative emotions, thoughts, and physical reactions are triggered by specific sounds.” Other labels include “select sound sensitivity syndrome” and “sound-rage.” Misophonia has not been classified as an auditory, neurological, or psychiatric condition; so far, no standard diagnostic criteria have been defined. Neither the DSM-IV nor the ICD-10 has included misophonia listed in their referenced problem. Unfortunately, there is little research on its prevalence or treatment.

Misophonia (and its related conditions–phonophobia and hyperacusis) can be remediated. The techniques for addressing inordinate reaction to noise must be researched. While Stage 5 is being implemented, FAA, industry and the medical profession should sponsor such research.

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