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Letter: 'Shortcomings' in noise modelling for Tri-Cities flight path proposals

Writer believes NAV CANADA should be held accountable for demonstrating why the changes are necessary.
Large passenger airline in flight with dramatic sky.

The Editor:

Re: Noise pollution among concerns raised by Tri-City residents opposed to flight path changes (Jan. 26, 2023)

Further to Diane Strandberg’s recent article, which I was quoted in, I would like to provide some additional information, obtained largely through discussions with NAV Canada representatives at their Jan. 16, 2023 open house in Coquitlam.

There appear to be shortcomings in the noise modelling. It is derived assuming aircraft flying over completely flat ground at sea level.

This data is then simply overlaid on the map with no consideration for topography, underestimating noise pollution levels for residences located above sea level (on hillsides and plateaus).

In reality, the aircraft will fly closer to the elevated ground, which would result in higher actual noise pollution levels in many areas compared to the noise model.

Additionally, the modelled aircraft will not necessarily be the loudest aircraft to use the new approaches.

Furthermore, there are a variety of methods used to assess aircraft noise impacts on communities, some being more accurate and relevant than others — it is unclear exactly which methodology, inputs and assumptions were used by NAV Canada in creating their model.

All aircraft equipped with new satellite navigation technology arriving from the east would plan to follow the new flight paths down over Coquitlam Mountain when wind conditions dictate.

Since aircraft must always land into the wind, the new approaches would be busiest during the spring and summer due to prevailing winds. This is when most residents are outside more and have their windows open.

Today, only 40 to 50 per cent of aircraft arriving at YVR are enabled with the new technology, but as airlines renew their fleets, traffic would consistently increase.

A NAV Canada representative provided an estimate that if all arriving aircraft were equipped with the new technology today, after excluding one-third (1/3) of inbound traffic due to in-flight diversions to other routes, over 100 aircraft would use the new routes per day and there would be times when there would be a steady stream of traffic, one after the other.

Claimed regional reductions in overflight of residential areas were primarily achieved by realignments proposed over southern communities (White Rock, Surrey, Delta) and by having aircraft fly more concentrated flight paths using "continuous descent operations" over those and other communities. 

The proposed alignments over the Tri-Cities are primarily driven by a desire to achieve symmetry with the southern realignments to benefit efficient aircraft operations.

It is important that this private corporation (driven primarily by commercial interests) is held accountable for demonstrating the necessity of their proposal to the public and for accurately and openly presenting the impacts it would have on our communities.

I encourage all Tri-Cities residents to inform themselves on this issue and to participate in NAV Canada's public consultation that ends Feb. 3.

It is also important to contact our elected representatives (city mayors/councils, federal MPs, and provincial MLAs) to let them know that this is an important issue to their constituents.

- Aaron Norris, Port Moody