Posts Tagged ‘aircraft noise’

HMMH Throwback Thursday (TBT): Field Trips in the Pre-internet Age

Thursday, March 27th, 2014

by Mary Ellen Eagan

My first data collection (“field”) trip was in the spring of 1985.  We were supporting litigation (at an unnamed airport), and needed to know how flight schedules had changed over time (in order to prepare comparison DNL contours).  I was given the daunting task of going to Eastern Airlines Headquarters in Miami (at the time, Eastern was the only known source of historic flight schedule information) to copy pages from the Official Airline Guide (OAG), which looked something like this. 

Official Airline Guide

Official Airline Guide

 

The data needed to be re-typed (into Lotus spreadsheets), sorted, etc. – just to determine average daily flights on any given route.

 

OAG flight schedules

OAG flight schedules

 

That’s how the glamor began.

From Miami, I flew to Portland, Maine for my first trip involving instruments (alas, I’ve been unable to locate a photograph of a Digital Acoustics 607 noise monitor).  Nick Miller and I were measuring noise levels near Naval Air Station Brunswick, home of Pat Wing 5 and the P-3 Orion Naval Patrol. 

 

NAS Brunswick, Maine

NAS Brunswick, Maine

 

What I remember most about that trip – and tell my girls every time we drive past the old base (the base is gone – it’s now Brunswick Executive Airport, but the Fat Boy Drive-in is still going strong!) is that I was so engrossed in managing the noise monitor that I actually screamed the first time an aircraft flew overhead.  In my defense, that plane (a P-3) was on short final and probably at 100’ altitude (I know, because I got to figure that out later) and very quiet.  It was my first experience with ‘startle’.  What I also remember is Nick’s equanimity in the situation, while inside he must have been wondering just how long my career at HMMH would last.

There are so many differences between then and now, but the thing I miss most is the opportunity to get to know colleagues on a personal level.  In those pre-Internet days, once the sun went down, we were done working for the day – no email, no work in the hotel room, no cell phones even to call home.  It left lots of time for exploring neighborhoods, which could sometime be a challenge near remote Naval Air Stations – but who doesn’t like a challenge?  For example, in the photo below, Bob Miller is seen defending me from an unseen rattlesnake near Midland (TX).  We may be way more efficient these days, but are we still having fun?

 

snake hunting near Midland, TX, 1986

snake hunting near Midland, TX, 1986

 

 

Throwback Thursday (TBT): My First Noise Contours

Thursday, March 20th, 2014

by Mary Ellen Eagan

At the risk of mixing social media platforms (and incurring an eye roll from my teenage daughter), I’d like to announce a new blog series at HMMH:  Throwback Thursdays.

This idea was sparked as a result of the recent renovation of our Burlington headquarters, and the desire to preserve this collage that was prepared for the occasion of HMMH’s 10th Anniversary in 1991: 

HMMH-the early years1981-91

HMMH-the early years 1981-91

Our team has invested significant time scanning each of the photos in the collage, and my hope is that we can find something interesting to say about most of them (well, there are some NSFW things that won’t be shared).

My First Noise Contours

I thought I’d start off with a photo of my first noise contours.  As the date indicates, it was November 1984 (yes, I am that old); I was fresh from Cornell and a summer Internship with the Massport Planning Department; still wearing Birkenstocks and going to Grateful Dead shows (yes, I am that old).  Back in the day, this is what noise contour development looked like:

  • Operational Inputs were developed by typing ATC flight progress strips (see below) into a Lotus 1-2-3 spreadsheet on the company’s only computer – a Xerox (which looked something like this): 

 fl-strips-computer

 

  • Flight tracks were developed in one of two ways:  (a) interviewing the Control Tower manager, who would describe nominal controller instructions to pilots (e.g., Climb to 1000’, then turn on course”), or (2) someone (guess who?) would sit in front of a radar scope marking radar return dots on a piece of acetate – literally, dot-to-dot flight tracks.  These days, I just smile at folks who get worked up for only getting a 99% radar track sample to analyze.
FAA Radar scope, circa 1980s

FAA Radar scope, circa 1980s

 

  • Then the real fun began!  We typed the INM “input deck” (I’m a version 2.7 girl – we old-timers mark our age by first model used) into the computer (my colleagues will tell you about their experiences with punch cards, and submitted it to Control Data Corporation (CDC) over a dial-up modem for processing.  Each run cost several hundred dollars – we did a lot of QC before submitting!   Assuming all went well, we then got to DRIVE to Waltham (20 minutes without traffic) to talk to Manny and get the output – a green and white computer printout and (hopefully) a large plot with contours!
MEE’s First Contours:  Groton-New London, November 1984

MEE’s First Contours: Groton-New London, November 1984

Next up:  Zipatone and Field trips of the 1980s!

 

Report from UC Davis Noise and Air Quality Symposium

Friday, February 28th, 2014

First, congratulations to Dan Frazee, 2014 winner of the Walt Gillfillan Award!  Until very recently, Dan was Director of Airport Noise Mitigation at San Diego International Airport where his department oversaw an award-winning residential sound attenuation program, conducted noise data management and led the community Noise Information and Education Program. Previously, he served as Noise Abatement Officer and Airport Operations Officer for the Sacramento County Airport System. He holds an FAA Airline Transport Pilot rating and is an FAA Certified Instrument Flight Instructor. He is also a retired USAF pilot and Army aviator with over 8,000 hours in rotary and fixed wing aircraft and previous work as a military Air Traffic Controller. He holds a BS in Education from The University of North Texas, a MS in Educational Psychology from The University of Texas at Austin, and is a Certified Member AAAE, and served as Chair of the Aircraft Noise working Group on the Environmental Services Committee for ACI. More importantly, he is one of the nicest human beings you will ever meet, and a good friend to many of us at HMMH.  We wish Dan all the best in his “retirement”, which promises to be busy. 

Frazee

This year’s symposium featured several new concepts, including a double-track (admittedly, not new, but something that hadn’t been done for a while), and a “Vendor Showcase” for folks to learn about new product offerings.  Session titles included the following:

  • Performance-Based Navigation: An Overview and Experiences
  • NextGen and NEPA
  • Recent Noise Research
  • Fuel Advances and Emissions Reductions
  • Helicopter Noise Issues
  • Noise Office Responses to Air Quality Inquiries
  • Sound Insulation: The Community View
  • A Decade of Research
  • Upcoming Significant Revisions to FAA Order 1050.1E
  • Health Effects of Aviation

I moderated this last one, and want especially to thank Dr. Anna Hansell of Imperial College London, who spoke about her work on the Aircraft Noise and Cardiovascular Disease near Heathrow, and Dr. Sarav Arunachalam of University of North Carolina at Chapel Hill, who talked about his work on health impacts from aviation emissions.  This is a topic we should all monitor closely.

A “perfect storm” – Recent actions by all three branches of the federal government address more types of aircraft noise, and acknowledge that adverse effects extend beyond traditional noise contours.

Thursday, July 18th, 2013

by Ted Baldwin

Serious federal attention to aircraft noise began around 1960, largely in response to community concerns (okay, complaints) related to the introduction of early air carrier jets (“airliners”), in particular the Boeing 707 and Douglas DC-8.

For the past half century, the federal government has largely focused its attention on aircraft noise associated with succeeding generations of airline jets at commercial service airports.  General aviation (g.a.) airports, g.a. jets, propeller aircraft, and helicopters have been a secondary focus of attention to all branches of the federal government, as illustrated by the following examples:

  • Legislative branch:  Congress has focused on laws phasing out older noisier aircraft over 75,000 pounds, which largely represent air carrier jets.
  • Executive branch:  The FAA’s development of the Integrated Noise Model (INM) has largely focused on modeling air carrier jets, as exemplified by the database’s most extensive coverage for that category of aircraft, with increasing dependence on substitute modeling surrogates as aircraft weight decreases.
  • Judicial branch:  Legal decisions have largely accepted arguments that significant noise exposure and associated liability extend only to the 65 decibel (dB) Day-Night Average Sound Level (DNL) contour, on which g.a. aircraft and helicopters have relatively little effect;  typically the 65 DNL contour from these aircraft alone encompass little – if any – off-airport land.

To build on the “ocean” metaphor in the title of this posting, the airline jet noise “tide” is ebbing, largely as the result of federal legislation and FAA regulations that force the retirement of 14 C.F. R. Part 36 Stage 1 and 2 jets over 75,000 pounds, and require applications for new “type certification” to meet Stage 4 requirements.  Local noise abatement and land use compatibility programs have complemented these federal actions (and frequently benefited from federal funding and implementation support).

One potential federal response might be to declare “mission accomplished” on the noise front, and turn the focus to areas where the tide is rising – both literally and figuratively; e.g., emissions-related contributions to climate change, which appear to be associated with storms that threaten coastal airports and result in operational delays at airports at all elevations.

However, recent actions show that the federal government is taking a different approach, and turning its focus to previously neglected – or at least lower-profile – noise issues associated with g.a. airports, g.a., jets, and even helicopters.  Again, this “changing tide” is reflected across the board at the federal level:

  • Legislative branch:  In the “FAA Modernization and Reform Act of 2012,” Congress prohibited, after December 31, 2015, regular operation in the contiguous 48 states of civil aircraft weighing 75,000 pounds or less that do not meet Stage 3 noise levels.  See http://www.gpo.gov/fdsys/pkg/FR-2013-07-02/pdf/2013-15843.pdf.)
  • Executive branch:  As summarized in its “Aviation Noise Impacts Research Roadmap,” the FAA is supporting a number of initiatives recognizing a broader range of noise issues, such as the accuracy of the INM for modeling g.a. aircraft and enhanced modeling of taxiway noise.
  • Executive Branch:  In a more applied case, the FAA adopted a final rule on July 6, 2012 that requires helicopter pilots to use the North Shore Helicopter Route when operating along the north shore of Long Island, New York.  The purpose of the rule is to “protect and enhance public welfare by maximizing utilization of the existing route flown by helicopter traffic one mile off the north shore of Long Island and thereby reducing helicopter overflights and attendant noise disturbance over nearby communities.”  (see http://www.faa.gov/regulations_policies/rulemaking/media/NYNShoreHelicopterFinalRule.pdf)
  • Judicial branch:  In a recent opinion that denied a petition by the Helicopter Association International (HAI) for judicial review of the preceding mandatory helicopter route, the U.S. Court of Appeals for the District of Columbia Circuit supported the other executive branches in their focus on lower levels of noise exposure related to operations by non-airline aircraft.  (see http://www.cadc.uscourts.gov/internet/opinions.nsf/1C20D137DFF53DAD85257BA600539826/$file/12-1335-1446255.pdf)

It should be noted that the Long Island helicopter route rule addressed in the preceding two bullets was initiated by two federal legislators representing Long Island residents – Senator Charles Schumer and Representative Tim Bishop – who conducted a meeting in October 2007 with the FAA, local helicopter operators, and airport proprietors to specifically address noise complaints stemming from helicopter operations along the north shore of Long Island.  While only the executive and judicial branches took formal action, the process involved significant input by these legislators as well.

The mandatory helicopter route is particularly significant because it represents divergence from several prior federal positions related to the longstanding “line in the sand” that the federal government has drawn at the 65 decibel (dB) Day-Night Average Sound Level (DNL) contour: 

  • First, it reflects major divergence from the prior federal position that reduction of sensitive land uses exposed to noise above 65 dB DNL was a de facto prerequisite for approval and support of noise abatement or compatible land use actions.  In its brief responding to the HAI petition, the FAA acknowledged that the route would not produce any benefit at or above this level of exposure, and noted that it “has authority to act without first demonstrating that a specific noise level has been exceeded.”  Furthermore, the FAA brief cited the “Long Island North Shore Helicopter Route Environmental Study,” which it had tasked the John A. Volpe National Transportation Systems Center to conduct.  That study concluded that prior to the adoption of the mandatory route, no residential population along the route was exposed to noise above 45 dB DNL, even on busy holiday weekends (e.g., around Memorial Day and July 4th, 2011).
  • Second, it reflected the first time – of which this author is aware – that the FAA relied on complaints as a fully sufficient basis for adoption of a formal noise abatement procedure.  In perhaps its most blunt statement regarding complaints, the FAA brief responding to the HAI petition stated “[w]hen people take the time to complain about helicopter noise to the FAA and their elected officials, there is a noise problem.”

The FAA’s justification for and defense of adopting a mandatory noise abatement rule based on noise complaints and with open acknowledgement that the benefit outside the 65 dB DNL contour by a 20dB margin is an extraordinary divergence from decades of FAA policy and decisions regarding noise compatibility actions.  As just one example, readers may recall that in its determination that the Naples (FL) Airport Authority (NAA) adoption of a ban on Stage 2 operations “was unreasonable and unjustly discriminatory” and therefore in violation of federal law, in part because the “NAA’s use of complaints … does not support a finding that the Stage 2 ban is reasonable.”  (”Director’s Determination,” FAA Docket No. 16-01-15, March 10, 2003.)

These recent actions by all three branches of the federal government clearly acknowledge that aircraft noise impacts worthy of addressing in the most formal manner need not be justified by federal land use compatibility guidelines, are not limited to particularly noisy aircraft, and do not even require quantification in decibel-based terms.

While the applicability of these actions as precedents in addressing other noise concerns across the U.S. will undoubtedly be the topic of vigorous debate for some time, airport noise stakeholders – including aircraft operators, pilots, airport proprietors, state and local government land use jurisdictions, airport neighbors, and others – should follow the federal lead in taking a fresh look at creative bases for demonstrating benefits and considering – or reconsidering – the full spectrum of noise abatement and compatible land use measures that might be applied to aircraft noise sources of local concern. 

That Crackly Sound

Friday, December 18th, 2009

by Doug Barrett

Four more days to go until the longest night of the year and it’s starting to get cold here in New England!  Last night’s low was around 14 degrees F. in Boston, and last weekend, up in New Hampshire, it was colder still.  My fabulous spouse and I live about five miles from Boston’s Logan International Airport, and depending on which way the wind is blowing, sometimes we are treated to a steady stream of departing aircraft.  The other day, after a particularly cold morning, she asked why the aircraft sound different in cold weather – both louder and “crackly” as she put it.

The short answer is that it’s complicated.  As for the long answer, I suspect that she’s noticing the dependence of atmospheric absorption of sound on temperature and relative humidity.  Leo Beranek said it better than I could: “energy is extracted from a sound wave by rotational and vibration relaxation of the oxygen molecules in the air.  The vapor content of the air determines the time constant of the vibration relaxation… In addition, this ‘molecular absorption’ depends in a major way on temperature.” (Leo L. Beranek, Noise and Vibration Control, McGraw Hill, 1971, P.170)

It’s especially interesting that at any particular relative humidity, molecular absorption peaks at a given temperature.  In other words, one can’t simply make a generalization that sound “travels” better when it’s cold outside.  Adding to the complexity, the effects of temperature and humidity vary dramatically depending upon the frequency of the sound.  In general, wider variations exist at higher frequencies.  Notice on the first figure below (reproduced from Beranek) that there is relatively little sensitivity to temperature or humidity at 500 Hz – only about 3 dB per 1,000 feet across a temperature range of 100 degrees F.  In contrast, at 8 kHZ, the second figure shows a whopping variation of up to 50 dB per 1,000 feet over the same temperature range.

Atmospheric Absorption for aircraft-to-ground propagation (500 Hz, 1,000 Hz, 2,000 Hz)

Atmospheric Absorption for aircraft-to-ground propagation (500 Hz, 1,000 Hz, 2,000 Hz)

Atmospheric Absorption for aircraft-to-ground propagation (8,000 Hz)

Atmospheric Absorption for aircraft-to-ground propagation (8,000 Hz)

Regarding the “crackly” sound, here are some molecular absorption values that I pulled from the figures: At 500 Hz to 1 kHZ (approximately speech frequencies), one expects molecular absorption at a rate of about 1 to 2 dB per 1,000 feet of propagation on either a pleasant summer morning (60 degrees F. and 50% RH) or on a nippy winter morning (10 degrees F. and 20% RH).  That is to say, at lower to mid-range frequencies, there’s not a big seasonal difference.  At 8 kHZ, however, one expects absorption at a rate of about 20 dB per 1,000 feet with the summer conditions, but only about 6 dB per 1,000 feet with the winter conditions.  Less high-frequency absorption with cold, dry weather equals more “crackly” sounding!