By Dr. Matthew Price, Chris McCann, Anthony Stiegler / La Jolla Light / May 15, 2023
The following has been updated and edited from the original version.
The FAA recently opened a public comment period on its Noise Policy Review for the San Diego International Airport, and the public comment deadline is July 31st.
The review will evaluate:
- Whether the current use of the “day-night average sound level” (DNL) should be the primary noise metric for assessing cumulative aircraft noise exposure;
- Whether and how alternative noise metrics may be used in place of or in addition to DNL;
- The community’s understanding of noise impacts and how to better respond to aviation noise concerns;
- The findings of ongoing noise research and more
The FAA held four webinars during May via Zoom, and, again, the public comment period closes July 31.
For more information, visit faa.gov/noisepolicyreview.
Quiet Skies La Jolla will be providing comments on the Noise Policy Review. For updates, visit quietskieslajolla.org.
We urge all affected areas of San Diego to submit comments by the July 31 deadline and that the San Diego County Regional Airport Authority sponsor and facilitate round-table meetings to encourage a unified voice from San Diego. We can achieve better results working together as a community.
This is an update on recent developments regarding the efforts to reduce commercial jet noise over impacted San Diego communities.
Don Scata, the FAA’s director of noise research and policy, gave the keynote address at the recent Air Noise and Emissions Symposium in April. He acknowledged that the FAA received many more noise complaints after it rolled out the NextGen concentrated flight paths nationwide. He noted the significant noise impact on “flight corridor communities” and that the FAA’s recent Neighborhood Environmental Survey reported a significant increase in reported annoyance complaints.
Scata announced that the FAA is open to considering additional metrics to measure noise levels and reassess thresholds, including modifying the level at which the FAA considers noise to be “normally compatible” or of “insignificant impact.”
A key question is how to measure the impact of aircraft noise on residents and communities. The FAA has traditionally used a decibel threshold, but recent research suggests that measuring the frequency of noise events is a more accurate metric of human annoyance, stress and resulting health consequences. While one overflight at 65 decibels may not bother you, 10 overflights in 30 minutes is another story.
Noise experts recommend that a standard that measures noise repetition and frequency, or the “N above” standard, be used, i.e., assessing the number of noise “doses” above a threshold after which noise becomes a significant stressor.
Aviation Impacted Communities Alliance
After the FAA rolled out its NextGen navigation program in 2016-17, communities across the country united under the Quiet Skies organization and a congressional caucus, advocating for the FAA to roll back NextGen and/or mitigate the human health harms.
San Diego, Los Angeles, Palo Alto, Baltimore, Philadelphia, Lake Tahoe, Boston and many others have joined the 67 members of the Aviation Impacted Communities Alliance to pool resources, coordinate efforts and work at the national level for change.
In the past, community groups have acted individually to get noise issues addressed in FAA reauthorization bills. But now a large coalition of community groups is speaking to Congress with one voice.
AICA is lobbying on Capitol Hill for solutions to address noise in communities more than a mile from airports (that are not within the 65-decibel day-night average sound level contours), require the FAA to take advice from the National Academies of Science on human health impacts from commercial jet noise, and require the FAA to devise action plans to alleviate noise and address community concerns, among others.
No single solution will work for all airports because geography, traffic constraints and external factors will require local answers. Flight dispersion and making use of the Pacific Ocean, however, are winning concepts for the entire greater San Diego community and should be implemented at the San Diego airport.
How to fix what’s broken
The NextGen project concentrated departures and landings over tight corridors, resulting in repetitive noise exposures to previously quiet communities. Communities affected by the concentrated departure paths include La Jolla, Ocean Beach, Pacific Beach, Point Loma and Mission Beach, all of which are central to San Diego’s tourism interests.
These communities participated in a series of meetings and workshops with the goal of recommending noise abatement procedures to the FAA. Proposals were made to disperse noise across three departure tracks so that no single community or group of residents will bear a disproportionate burden of living under or adjacent to a flight path.
The communities failed to come to an agreement about where to locate the three recommended dispersed flight tracks. Although the dispersion proposal would have reduced noise for thousands of residents (mostly in Mission Beach, Ocean Beach and Point Loma), a slight shift in noise would have affected a dozen or so homes in Ocean Beach.
The airport declined to move forward without unanimity. However, the airport committed to reevaluate the dispersion proposal in 2026, and it is important that all San Diego communities collaborate and reach a consensus on a solution that provides a win for the entire region.
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In 2017, the Federal Aviation Administration began to implement the NextGen Southern California Metroplex project, which modified commercial flight patterns to and from San Diego International Airport to optimize the efficiency of airspace use.
This led to a further concentration of flights, or “highways in the sky,” above several San Diego communities. Recent scientific research and objective data indicate that concentrated exposure to repetitive jet noise may cause serious medical harm, including cardiovascular events such as stroke and heart disease, along with cognitive processing problems such as decreased school performance for children, sleep disturbances and increased stress.
Similarly, small-particle jet emissions are linked to serious human diseases like respiratory ailments.
Dispersing jet noise and particle emissions is an acknowledged antidote to concentration and is defined as “the process of introducing track variability by changing aircraft lateral position enough to spread out repetitive and intrusive noise events experienced by people living under highly concentrated flight paths” (UC Davis Aviation Noise and Emissions Symposium, February 2021).
Dr. Matthew Price, Chris McCann and Anthony Stiegler are co-founders of Quiet Skies La Jolla.
Editordude: the above has been updated and slightly edited from its original version at The La Jolla Light.
{ 3 comments… read them below or add one }
I believe the standards used at SAN are CA standards of CNEL vs DNL with CNEL adding 3 dB to aircraft between 7pm and 10pm. CA regulations show slightly higher noise levels.
At this point, the key to reduced noise is an accelerated phase-out of current Stage 3 aircraft such as the 737NG and 320ceo series aircraft, and replacing them with much quieter 737MAX and 320neo aircraft.
The government uses a decades-old law phasing out Stage 2 aircraft, which is now a moot point since they are all gone. Stage 3 aircraft with current generation engines (not MAX or neo) are unrestricted – the government needs a new law to establish a phase-out of these current aircraft in the 10 pm to 7 am time frame first, then all together in about 20 years. Accelerated phase-out at airports with housing in the 65 contours like SAN, SJC, SNA, and others would be laudable and appropriate.
While I agree with the comment above, I believe the time has come to change the criterion for establishing incompatible noise areas. There is increasing research and data that shows that there is a cumulative effect of single event aircraft noise levels on a number of health issues, including hearing loss and cardiovascular damage among others. For example, the CNEL averages the total number of events over a 24 hour day, which understates the size of the contour. But more importantly, it is very difficult to correlate the CNEL to health impact. As a minimum, the FAA should add a single event criterion to the current 65. It is easy enough to convert measured single events over a month or a quarter to a histogram (number of events as a function of event magnitude), which can then be correlated to anatomical damage, much like fatigue of a metal is done. The two areas that would benefit from the new criterion would be those closest to the current ZZOOO and PADRZ SID departure tracks. I have taken measurements at several houses in South Mission Beach and the airport authority has used their portable monitor at my house as well. This data simply needs to be connected with anatomical damage models to derive the new criterion.
One more point. If damage models show that single events outside the 65 correlate with anatomical damage, can you imagine what the models would show for those living within the 70 or 75 dB CNEL. Right now the emphasis has been on the 65, but in my opinion, this is a distraction. The people living within the 70 near the ZZOOO or PADRZ flight track, need to have the airport authority set up their portable noise monitors at they houses. The airport authority will provide the raw data if requested which I can put into my software that does histograms. If this shows severe or rapid damage in combination with the airport reaching capacity, perhaps this becomes the perfect storm.