Duluth airport looks to quell noise concerns
An in-depth report could shape a plan to reduce friction with neighbors.
DULUTH — Dwight Morrison is no stranger to the sound of aircraft, as he has lived off the west end of Duluth International Airport’s longest and most-used runway for more than 40 years. But he has yet to make peace with his noisy neighbor.
Morrison said overpassing jet aircraft sometimes make his whole house shake.
“It even fractured a chandelier in our dinette,” he said.
Yet, Duluth International receives a relatively low volume of noise complaints compared to many other airports, according to Tom Werner, its executive director.
“The community and the region at large is very supportive of Duluth International Airport — the economic impact that it has, the jobs that it provides,” he said.
While Werner said there has been no large outcry about noise, to date, he acknowledged: “There are a few instances where neighboring residents do have issues with the current noise. And we’ve invited them to take part in this noise study process.”
The airport commenced work in August 2019 on a comprehensive Part 150 Noise Study, a document that is just now undergoing review by the Federal Aviation Administration .
A Part 150 Study doesn’t usually take quite so long to complete, but the pandemic and the ensuing complication of collecting comment through public meetings remotely initially slowed the process, explained Jesse Baker, managing consultant with Landrum & Brown, the global aviation planning and development firm hired to lead the project.
“The goal of the noise study is to understand where noise can be hazardous to the uninvolved public neighborhoods outside the airport and then also to identify ways we can reduce not only current noise, but reduce the impacts of possible future noise issues and incompatible uses of land around the airport,” Werner said.
It has been more than 20 years since Duluth International conducted its last such study, at great expense. To date, the latest report has cost more than $790,000 to assemble.
“There had been enough that has changed here, in terms of the fleet mix that comes in and out of the airport, as well communities growing up around the airport, that we really needed to take a fresh look at what noise was doing in the community,” Werner said.
He said noise produced off airport property by civilian aircraft — such as those flown for commercial and general aviation purposes — generally was found to fit within acceptable limits. However, that was not the case for all aircraft using the airfield, namely the military F-16 jets regularly flown by the 148th Fighter Wing of the Minnesota Air National Guard.
Lt. Col. Scott Prom, operations support squadron commander for the 148th, concedes that taking off in an F-16 is a loud endeavor. It typically involves kicking in engine afterburners to get the jet off the ground and to make it climb safely and effectively.
Given the choice, pilots probably would choose not to use afterburners, which consume large quantities of fuel, but Prom said the weight of the aircraft is a key determinant.
“Since we have itty-bitty wings, we need a lot more thrust to fly. So, the majority of our configurations and our weight require afterburner takeoffs. So, that’s where a lot of the noise comes through,” he said.
Morrison questioned whether many of the aircraft using Duluth International need to be using quite as much thrust as they are though, suggesting that throttling back could create less noise.
However there also are advantages to high-thrust afterburner takeoffs, according to Baker.
“It moves them up and out of the area quicker,” he said, explaining that the noise impact is diminished with altitude. Baker also pointed out that it’s best not to take any chances getting airborne with aircraft that are often loaded with ordinance.
While takeoffs often necessitate the use of noisy afterburners for safety’s sake, Prom said landings are another matter. He noted that the Guard has in the last six months, adopted some procedures “so we’re coming in at higher altitudes from different directions to disperse the noise.”
Prom said pilots also can often use an “idle descent” from altitudes as high as 8,000 feet, where they throttle back and essentially glide into a landing under minimum power.
“So, that’s one thing we can safely do. It’s just on takeoff we don’t have that many options,” he said.
Audra Flanagan, a spokesperson for the 148th, reported the unit received 25 noise complaints in 2021, but she added that many callers simply want to ask what’s going on. She said the Guard has stepped up advance efforts to inform the public via local media outlets, as well as social media, when special exercises in specific areas are planned, especially when night missions are to be conducted. Flanagan said that outreach has helped.
Prom said regular nighttime training is a must to keep unit members’ skills sharp.
“We understand that we make noise, but we’re doing everything in our power to mitigate that as much as possible, while keeping safe and being ready to perform our state and federal mission,” Prom said.
Flanagan said the 148th has appreciated the local support it has received as Duluth’s eighth-largest employer with 1,062 people on its payroll, including 470 full-time and and 592 part-time members. An economic impact study estimates the unit contributed about $105 million to the economy in 2001.
But Flanagan also accepts the need for public scrutiny, saying: “We need the community to take an honest look at us once in awhile.”
The greatest levels of noise are found to the east and west of Duluth International‘s main runway, which is oriented in the same direction.
Baker said the study looked at the possibility of extending the airport’s other runway which runs at a northeast/southwest bias to disperse some of the air traffic. The current runway is too short for F-16s to safely use on a regular basis.
But such an extension would cost at least $30 million, and because of prevailing winds, the study determined it would be usable for only about 5% of the 148th’s flights.
Morrison questioned the legitimacy of the report’s noise modeling which is based largely on an FAA database. Morrison referred to the modeling as “a mathematical construct,” rather than a reflection of reality.
Baker said the sophisticated noise modeling system the FAA has developed distinguishes between the noise produced by about 5,000 different types of specific aircraft and takes into account the frequency of operations at different times of day and night.
The study also did include some on-the-ground monitoring.
“But one of the challenges can be background noise, especially when you’ve got a monitor a couple hundred feet away from a highway, with trucks and air brakes contributing noise,” Baker said.
If Duluth’s Part 150 passes muster, a subsequent noise mitigation plan could cost up to $19 million to execute, with the FAA covering 80% of the authorized cost. Duluth International would be left to come up with the remaining 20% — up to an estimated $3.8 million. Werner said those figures represent the top end of the anticipated cost spectrum and predicted the actual plan adopted will be more modest in scale.
Baker said he considers it most likely the mitigation plan that is approved will be more in the range of $4 million to $6 million, requiring a local investment of $800,000 to $1.2 million.
Given the outsized role that military aircraft play in creating a racket at Duluth International, Baker said Duluth likely could make a strong case for additional assistance from the U.S. Department of Defense, and the airport is working to explore what resources could be brought to bear on that front.
That money could go to cover soundproofing measures, such as improved insulation and upgraded windows, for up to 62 homes.
Seven homes located off the ends of the airport’s main east-west runway are subject to enough noise that they could qualify for outright acquisition by the airport, but Werner stressed any such sales would be voluntary and not compelled.
If those residents do not wish to sell, Werner said they could alternatively accept what’s called an aviation easement, where they would receive a financial payment as compensation for the right to use the air space above their homes.
Morrison said the “mitigation plan” seemed to have less to do with reducing noise than paying off neighbors to tolerate it.