Final Denver Metroplex flight-path study upholds planned changes

FAA plan could bring new routes for several airports, including Centennial


The federal government’s final analysis of a plan to reroute airplane traffic in the Denver metro area didn’t offer changes to proposed flight paths for Centennial Airport that have riled up local officials.

Wheels have been turning for years on the Federal Aviation Administration’s plan to optimize arrival and departure at local airports — it’s called the Denver Metroplex project, and it includes Denver International Airport, Centennial Airport and some others. An FAA study, called a draft environmental assessment, looked at impacts the project could have on noise, air quality, wildlife, and historic and cultural resources.

The proposed change in flight paths is expected to have “no significant impacts” on those aspects of the project’s area, including metro Denver and the Greeley area, according to the April 22 draft EA.

Now, the final version of that study is out. And although it shows that the FAA made changes to a proposed flight path over the Boulder area based on public complaints, the notable planned new paths in south metro Denver remain unchanged.

“We have the very same concerns as before,” said Robert Olislagers, executive director of Centennial Airport. “The FAA has ignored perfectly good reasons to go take this process slowly and carefully.”

The final study, released Nov. 18, does not change the determination that the plan will not have significant impacts. That likely means a further review, called an environmental impact statement, isn’t necessary before the plan is put into action.

But “no final decision has been made,” said Allen Kenitzer, an FAA spokesman. Comments can be made through Dec. 20 on the FAA’s website.

No significant impacts have been found to be expected by any draft EA or final EA of the 11 active or completed Metroplex projects around the nation, and all projects have been reviewed with EAs to this point, Kenitzer said.

Paths at issue

Centennial Airport is still urging the FAA to remove two proposed flight paths from Metroplex.

Planes today already travel the area that one proposed path, PINNR, would cover in the Denver area, according to the FAA. That’s a proposed route that travels south, roughly above Interstate 25, starting around Greeley and turning southeast over the Denver area.

The proposed BRNKO route would take arrivals from the northeast that currently stay east of I-25 and move them farther north, joining up with PINNR near Greeley and traveling in that same corridor as flights move south.

BRNKO only entails about six flights per day on average that would be moved from an older corridor, according to the FAA. Centennial Airport sees about 1,055 daily takeoffs and landings combined, but most of those would not use the proposed Metroplex routes, according to the FAA.

But Centennial Airport argues the BRNKO route will put pilots over unsafe territory: the foothills, where volatile wind conditions can be unpredictable, the airport has said.

Boulder area gets change

The FAA has made a handful of tweaks to the list of proposed new flight paths, and one path, the ZIMMR, represents a change for the Boulder area.

The existing FOOOT path — which the ZIMMR would replace — flies directly over the south-central portion of the City of Boulder, and an update to the proposed ZIMMR moved the path even farther to the south than the original proposed change, according to the final EA study.

“Recognizing the important role community engagement plays for the successful implementation of the DEN Metroplex, public comments were reviewed and considered for potential changes to procedures,” the final EA read.

From April 22 through June 6, the FAA accepted comments on the draft EA through the FAA website, at public meetings, and through physical mail and email. The more than 500 comments received — from private citizens and groups, elected officials and government bodies — are all included in the final EA with general responses to each comment based on the topic it deals with, such as noise or frequency of flights.

“Looking at the impacts on Centennial Airport and our surrounding impacted communities, nothing appears to have changed,” Olislagers said of the final study compared to the draft.

Questions ‘unanswered’

Olislagers has argued that the FAA didn’t consider the impact of the part of flight that occurs below 3,000 feet above ground, and that leaves unclear how much communities could be affected. Littleton, Centennial, Cherry Hills Village, Lone Tree, Castle Rock and other nearby cities could experience notable effects, Olislagers said.

The airport, in a June 5 letter to the FAA, contended that the final part of flight wasn’t adequately analyzed by the agency, “leaving the most important concerns, noise and overflight at the lowest altitudes over those communities unanswered,” the letter read.

In the final EA, the FAA clarified that all noise modeling was done from the surface to 18,000 feet above ground, Kenitzer said, and all noise results were reported at ground level. Kenitzer did not directly address an emailed question of whether noise was analyzed for the portion of flight that occurs below 3,000 feet above ground, specifically, or just the part of proposed paths at which planes would be above 3,000 feet.

It appears that, after changes to the Metroplex plan shown in the final EA, fewer people would experience notable noise increases. The draft EA reported that about 100 people in rural parts of Jefferson, Adams and Elbert counties would likely experience an increase of 5 decibels in areas where the average noise would usually vary between 45 and 60 decibels. Conversation in restaurants generally hovers around 60 decibels, according to a Purdue University chart. Upper-70s levels are annoyingly loud to some people, the chart said.

Now, about 70 people would experience a 5 dB increase in areas where average noise usually varies between 45 dB and 60 dB. One is located in unincorporated Jefferson County, and the other sits in unincorporated Elbert County.

But that’s the extent of the notable noise changes, according to the FAA — and only increases of 1.5 dB or more in areas exposed to 65 dB and up are considered to “exceed threshold of significance,” according to the draft report.

Studies don’t apply, FAA says

In the June 5 letter, Centennial Airport also pushed for the FAA to complete more studies mandated by the FAA Reauthorization Act of 2018, a law passed by Congress, before it puts the Metroplex plan in motion. Those studies focus on the FAA’s “community involvement” practices and the effect of noise on health, among other items, according to the airport’s letter.

The FAA said it will comply but that it isn’t required to do so before Metroplex is implemented.

“Congress did not place a moratorium on project implementation, including the proposed Metroplex projects,” Kenitzer said.

Legal action to return

Earlier this year, Centennial Airport took legal action — a petition for review — against the Federal Aviation Administration over the Metroplex project.

That move came in the U.S. Court of Appeals for the District of Columbia Circuit. In the June 19 legal filing, the Arapahoe County Public Airport Authority — the government body that oversees the airport — asked the court to review the FAA’s study, its determination that an environmental impact statement isn’t needed and its proposed changes in flight procedures.

The airport later withdrew its case because the filing was premature, and the court formally dismissed the case Aug. 16. The airport will refile its legal action, but a date is not yet certain.

“We’d also ask that concerned communities and counties representing citizens should file an amicus brief with the court once the Centennial Airport refiles its petition for review, to preserve and strengthen standing,” Olislagers said.

Metroplex, Centennial Airport, Denver, flight path, FAA, Ellis Arnold


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