FAA Denver Metroplex FONSI – better process?

DEN proposed Metro AT plan
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FAA Issues Record of Decision for Denver Metroplex Project


WASHINGTON—The Federal Aviation Administration (FAA) has issued a Finding of No Significant Impact/Record of Decision for the Denver Metroplex project. The Finding of No Significant Impact/ Record of Decision, as well as the Final Environmental Assessment, are available on the Denver Metroplex website.

The decision enables the agency to move forward with the project, which will use cutting-edge satellite navigation to move air traffic more safely and efficiently through the area. Satellite-based routes will allow for more direct and efficient routing of aircraft into and out of Denver and surrounding airports, enhancing aviation safety and efficiency, and potentially reducing flight delays.

Prior to making the decision, the FAA conducted thorough environmental reviews, including 24 public workshops and approximately 78 stakeholder briefings in the Denver metro area. The agency also held two public comment periods totaling 75 days and evaluated and responded to more than 975 comments.

The FAA plans to implement the procedures on March 26, 2020.

The FAA’s environmental review for the project indicates some people will experience slight noise decreases, some will see no changes, and some will experience small noise increases. Additionally, some people might see aircraft where they did not previously fly after the Denver Metroplex procedures are implemented.

Some flight track dispersion will continue to occur after the new procedures are implemented because the Metroplex project includes a number of existing procedures. In addition, air traffic controllers will need to occasionally vector aircraft for safety or efficiency reasons or to reroute them around weather systems.

The Denver Metroplex website includes Google Earth features that enable people to view current and projected flight paths associated with the project.

Page last modified: January 24, 2020 3:40:36 PM EST

NextGen AT graphic




The FAA described this new, more accurate and safer navigation technology as an environmental advance. That characterization is true on a macro basis, but experience has proved that the implementation on a micro basis has noise consequences. The lessons of Baltimore, Boston, Burbank, Charlotte,  Miami, Phoenix, San FranciscoSan Diego and Washington as well as some critical judicial reviews of the procedures used should have taught the FAA teams who are charged with explaining the  technical intricacies of the NextGen technology, of the complexities of the ATC system and its design (balancing safety, efficiency and the environment) and of the consequences on a local basis.

typical Next Gen impact tracks

For the DEN Metroplex ATC environmental review the FAA engaged in a Community Involvement process that encompassed 23 select official briefings, aviation stakeholder briefings, and public workshops. These Community Involvement activities occurred between November 2015 and December of 2018. The FAA’s outreach included two public comment periods totaling 75 days and evaluated and responded to more than 975 comments,” A total of 42 meetings and/or briefings were conducted throughout the Study Area during this timeframe. As a result of the public workshops held along the Front Range, 866 email comments and 61 written comments were received and considered in the procedure design process. Design changes were made to preliminary designs and in all cases where appropriate, were carried forward to the Proposed Action for this project as a result of the extensive Community Involvement process.


The Denver team identified specific areas which were points of likely increased noise:


To localize the information, the team produced boards to demonstrate the precise impact for the citizens, like this:


DEN outreach AT Boards








The  153 page ROD starts with a rudimentary explanation if the science and the art of ATC design [including the advanced attributes of NextGen-RNAV, RNP and OPD) (p.1-3 to 1-12). The writers then move to the specifics of the Denver airspace, in particular to the existing constraints which limited alternatives—Class B Airspace, Special Use Airspace). The existing SIDS and STARS structures were explained. The airports to be included were stipulated. (collectively, p.1-13 to 1-22). Each of these sections provided useful explanations why all community input could not be accepted.

In defining the Purpose and Need, p. 2-23 to 2-39, the document explains more of the constraints:

  • Lack of flexibility in the efficient transfer of traffic between the en route and terminal area airspace;
  • Complex converging and dependent route ATC procedure interactions;
  • Lack of predictability in the efficient transfer of traffic between en route and terminal area airspace.

The changes proposed vs. alternatives were measured against the technical aspects of NEPA (remainder of Chapter 2 plus all of Chapter 3). Finally, the report finds the rationale for selecting the new Metroplex ATC map.

Granted, the jargon is arcane and the logic obtuse, but the record provides a reasonable explanation for the new TC routes. Unfortunately, any final selection will impact some more than others. Thus, there still are some opponents:

As feds prepare to shift DIA air traffic patterns, Gilpin County is the latest community to dread plane noise

Residents fear FAA’s Metroplex plan will funnel heavy air traffic over their homes

Gilpin County residents, for example, are concerned that the shift of westbound air traffic to the south will disturb historic sites, aside from the obvious issue of increased noise from planes.

Despite FAA’s statement that it “held two public comment periods totaling 75 days and evaluated and responded to more than 975 comments,” Gilpin County residents told The Post that they never got a meeting, and letters to the FAA from the offices of U.S. Rep. Joe Neguse and U.S. Sen. Michael Bennet went unanswered.


Final Denver Metroplex flight-path study upholds planned changes

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

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.

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.

DEN east patterns proposed







There are indications that an appeal is imminent; so, more will be heard about Denver and perhaps a Court of Appeals will provide further judgment about the FAA’s continuing effort to meet the relevant laws!!!




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