Going to the FAA presentation at Boulder—NINE THINGS TO KNOW

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Going to the FAA presentation at Boulder—


Federal Aviation Administration Announces Public Meeting in Boulder for Denver Metroplex Project

 2nd Iteration NextGen 

PBN and TBFM only :concentration of noise

Definition of Alternative– safe, efficient and environment– needs Expert

If you plan to attend the FAA presentation in Boulder, CO, be aware that it will be different than many of the past revision of a Next Gen airspace. The new technology is being applied at major airports all over the country. Denver International was one of the first to have these safety, efficiency and environmental benefits implemented and then approved under NEPA in 2016.

Now, the FAA is redesigning airspace and addressing inefficiencies, introducing new Performance Based Navigation (PBN) procedures, and making use of Time Based Flow Management (TBFM) to make the Denver Metroplex airspace more efficient and improve access to its airports.

The representatives will proudly point to the benefits of these newly plotted Air Traffic Routes. Both PBN and TBFM reduce the aircrafts’ emissions, lower their noise footprint and are safer. The proposed DEN AT architecture will accomplish all of that.

The FAA team at the Meadows Branch may not go into great detail explaining how the concentrated impact of these new flight patterns MAY increase how this new configuration will be impacted. As described in greater detail in this previous post, the FAA’s traditional measurement, which has been approved in the past by the EPA, the Council on Environmental Quality and many US Courts of Appeal, is not as sensitive to measuring this new phenomena.

[a generic example, not DEN]

What’s the difference?

The  precision of the PBN technology and implementation CONCENTRATES THE NOISE IN A SMALLER AREA. The residents in these areas may be experiencing substantial increases over their historic noise levels (+10 points on the scale equals a doubling of the loudness). Further, the RNP addition to the noise may not reach the FAA’s long standing threshold of 65 dBA; so the NEPA review may find that this change does not preclude the implementation. What sets the DNL “energy average” apart from a mathematical average is that for every increase of 10 dBA in a noise level, the energy is increased by a factor of 10. For example, an event of 70 dBA contains 10 times the energy of an event of 60 dBA or one hundred times the energy of an event of 50 dBA.

So what should an average citizen do as she/he enters the library

FIRST, the FAA has a technical, not a political, view of noise. Yes, in 2017, Mayor Suzanne Jones sent a letter on behalf of the Boulder City Council addressing concerns about increased airplane noise over the city of Boulder and requested that the FAA reconsider route options to help mitigate air traffic over the city. That initiative help cause this forum to be scheduled, but now the process is in the hands of career employees who are largely inured against such efforts.

An avalanche of FORM LETTERS is not likely to alter their technical position. Some poor assistants will be tasked with counting them and the FAA’s typical response will be buried in a footnote.

SECOND, while you may feel that the FAA’s 65 DNL standard is inappropriate, such a policy change is not within the authority of this review. The officials in attendance are involved in implementation. The folks who can change standards will not be in attendance.






THIRD, your best approach is to deal with the FAA on technical grounds. The FAA experts are more impressed with professionals in noise measurement (acoustics), land use, air traffic architecture, ATC procedures, aircraft performance, flight routings’ efficiency and SAFETY. The most powerful approach to trying to impact the FAA’s final decision is to propose safe, efficient alternatives which also benefit your community. The design of the den airspace architecture involves balancing SAFETY, EFFICIENCY and the environment. A proposed alternative should try to recognize and optimize those goals.

FOURTH, individual, well-considered comments are useful, but a consolidated position is the most powerful voice in these proceedings. Noise transfer tends to be a zero sum game; Community A is ecstatic and Community B is furious. Such split decisions allow the FAA to move forward with its preferred option. “No one can agree; so the original proposal obviously is fairest since all are equally opposed” will be the opening line of the FAA final record of decision. Working among communities, especially those who know the particular nature of their specific residential areas, commercial developments, noise sensitive areas (i.e. schools), noise proof uses (i.e. major transportation corridors), etc. can identify geography in your areas which can accommodate the overhead air traffic and those to be avoided. Some consolidated position is MOST LIKELY to have the greatest impact.


FIFTH, the FAA representatives are there to outreach. To them, that means that they are there to explain what the proposal is. LET THEM DO THAT; after a while you may become annoyed at the length of their soliloquys. They will finish and then likely ask “any questions”; your patient attention will magnify the degree to which they indeed listen.

It is quite likely that the FAA representatives will speak in jargon and use many abbreviations. Actually asking him or her what “ARTCC” means will reinforce that they are technical experts, a form of subtle flattery.   

There will be several different stations at each meeting; some of the staff presenting are likely to be expert in the science of Air Traffic Control. While others will be more involved in less obtuse aspects of the operations. The second category is more likely to listen to your inputs. Take the opportunity to converse with her of him.

SIXTH, NextGen provides many environmental benefits on a macro basis; however, on a micro basis, as this chart shows, RNP tends to concentrate noise along the precise routes created by this navigational upgrade. The FAA’s traditional noise measurements have not fully captured, to the satisfaction of the population living underneath these tracks, the impact along these corridors.








The next diagram depicts the arrival patterns. Particularly with OPD, the noise should be lower. Basically cruising from altitude reduces dramatically this major source of noise.

In order to better assess the change in noise, you might ask the FAA for copies of the old Northwest arrival traffic patterns and their noise contours. The FAA should have available maps with the precise metes and bounds of the tracks as well as the projected noise contours. They might also have the tables of data which supports their estimates; this information will look like gibberish to the average citizen, but in the hands of acoustical engineers they could help support requests for change.




This is where the impact maybe greatest, because these are the patterns where the power is being applied. Albeit that both the engines generate less noise and the aircrafts’ improved lift performance places them higher above the ground, the concentrated flight tracks have been a source of neighborhood complaints at other airports.

ASK THE FAA PRESENTERS FOR THE PRECISE LONGITUDE AND LATITUDE OF THESE DENSE SEGMENTS. The posters may not include such detail, but you are entitled to know exactly where these “boxes” will be located. Plot these RNP tracks on a map and assess the impact on these neighborhoods.

EIGHTH:  Do not assume that the FAA knows what you know. Bring your own maps of noise sensitive areas in your communities. The FAA knows the air better than the ground. Their proposed ATC designs primarily optimize the routes and procedures controlled by the FAA professionals. They will try to identify what points to avoid, but they will not know your neighborhood as well as you do. Be judicious in your marking of your map. Not every inch of the neighborhood should be claimed as incompatible uses. Try to cite the FAA criteria to support your position.

NINTH, the point of this exercise with the FAA to have the information which allows you to make them aware noise sensitive areas under these RNP tracks.  In your comments submitted after the public sessions, it is useless just to say no. The FAA has invested time and effort into designing this system. No alternative proposed makes it easier for the staff to adopt what they saw as an optimal solution originally.


An effective submission needs to define the specific conflicts (details of what incompatible use is there) alternative corridors, by an AT expert, should be completed and submitted to the FAA. It is important to remember that the FAA’s decisional criteria are SAFETY, EFFICIENCY and the environment. A counter proposal, which fails to incorporate the first two principles, can be easily rejected. A sophisticated compromise, which includes the FAA’s primary standards and which minimizes negative community impacts, has a greater likelihood of being adopted.

The average citizen and even brilliant scholars/scientists/engineers at the University of Colorado and/or NCAR do not have the experience designing airspace to be acceptable to the FAA. There are experts who can assist and who have experience creating win/win options.














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