A Simple Noise Abatement Strategy

The operation of the new Brisbane airport runway has sparked public outcry, anger and furious debate.

While that debate rages, however, a simple truth is being ignored; it’s a truth that no doubt the Brisbane Airport Corporation and the airlines are hoping that nobody notices, while instead they talk endlessly about Air Traffic Control rules and community consultations.

The simple truth is this: the New Parallel Runway isn’t actually needed.

That’s trivially true today, for the obvious reason that the airport functioned perfectly well last year with only one runway, and traffic in 2020 is only a small fraction of last year’s. But it’s also true for tomorrow, and next year, and for at least ten years; more likely even longer than that.

It’s not needed for ten years or more.

This simple truth is based on figures and arguments from BAC themselves, and on hard data from the Federal Bureau of Infrastructure and Transport Research Economics.

Why, then, if it’s not needed at all, is it being used to fly planes on new flight paths that are causing significant distress and hardship for many Brisbane suburbs, where planes never flew before?

More to the point, if it’s going to be used—even though it’s not actually needed at all—why shouldn’t it be restricted to only over-water operations? If it’s not needed at all, it’s certainly not needed for new, over-suburb flight paths. Removing those would instantly eliminate all of the problems that are causing so much distress and debate. What’s more, this obvious solution has also been proposed by experienced international pilotsi.

It’s that simple.

The new runway isn’t really needed because there aren’t enough flights.

Current operations at Brisbane airport are based on a number of badly flawed assumptions and demonstrably incorrect projections, errors that the industry has known about for years but about which they’ve remained silent. The simplest demonstration of this is that when they proposed the runway BAC predicted a nearly 100% increase in traffic from 2000 to 2020. The actual amount? Less than 50%.

Consider: last year Brisbane airport operated successfully on a single runway. Not only that, but last year those traffic volumes at Brisbane airport were also far lower than the volumes BAC themselves had identified as requiring a second runway. And that was before Covid. In post-Covid 2020 the traffic volumes are mere fractions of 2019 levels. IATA themselves predict that traffic will probably not reach pre-Covid levels until 2024, four years from now. So it will probably be four years before traffic volumes have returned to 2019 levels—levels that still, demonstrably, didn’t actually require a second runway.

So if it’s not needed now, when is the new runway actually needed, if ever?

BAC themselves identified a threshold of 256,000 traffic movements per yearii as the level at which the lack of a second runway would constrain operations. By contrast, in pre-Covid 2019 there were only 195,000 traffic movements—which coincidentally is about the same traffic volume that BAC had optimistically, and wrongly predicted would happen by 2010!

To reach BAC’s threshold for a second runway would require a massive 33% increase in 2019 pre-Covid traffic levels.In stark contrast, the actual total traffic increase at Brisbane, not just in one year from 2018 to 2019, but in the five years from 2015 to 2019 was a meagre 0.39%iii, from 194,000 movements to 195,000 movements, and that was before the pandemic!

In other words, Brisbane could have easily operated on a single runway in 2020 even if the pandemic hadn’t happened.

Here are the figures, comparing BAC’s traffic forecasts and growth forecasts with reality.

Table 1: Comparison of BAC projections from the BAC Master Plan and Federal Government actual figures

Screen Shot 2020-11-03 at 3.59.28 pm


  1. Drawn directly from Tables 2.2 and 2.4d from the BAC Master Plan

  2. This is not the actual 2020 value, but an extrapolation for comparison purposes assuming the pandemic hadn’t happened. It uses the 2019 figure of 195,173 movements, increased by the average growth from 2015 to 2019.

  3. From the Federal Bureau of Infrastructure and Transport Research Economics https://www.bitre.gov.au/sites/default/files/documents/webairport_cy_1985-2019.xlsx

It’s obvious that BAC’s estimates of growth were significantly wrong. That’s not surprising; seeing twenty years into the future is a difficult task. However what matters now is what the conditions are today, and what we can predict. Clearly the new runway isn’t needed now, and Covid has completely changed the world, including aviation. So when is the runway actually needed?

Even if we assume BAC’s discredited and optimistic Compound Annual Growth Rate of 2.8%iv, it will take another 10 years starting with 2019’s traffic, which is something IATA predicts won’t be until 2024. That is, it will take until 2034 to exceed 256,000 traffic movements, the point at which BAC say that a second runway is required.

Table 2: Projected traffic movements/year with BAC’s assumed compound growth rate of 2.8%

Screen Shot 2020-11-03 at 4.00.02 pm

If growth were anything less than BAC’s projected 2.8%—remembering that from 2015 to 2019 it was actually seven times less—then that single runway limitation wouldn’t apply until some time long after 2034!

To look at it another way: even if traffic levels miraculously and impossibly returned to pre-Covid levels in 2021, and even if growth happened at BAC’s discredited and highly improbable predicted rate, it would still be 2031 before the second runway was needed to handle additional traffic.

At least eleven years from now…

Which raises the obvious question: if it’s causing so many problems and it isn’t really needed, why is the new runway being used at all, and if it’s used, why is it being used the way that it is?

Why is it being used, if we know that all the new flight paths are actually not needed for at least ten years, and more probably fourteen? Why is it being deliberately used if we know that since it was opened its use has been the cause of widespread community outcry, easily demonstrated by newspaper articles, radio and TV interviews, and parliamentary petitions. Why use it at all?

Or, more practically, if it is going to be used, and using the new over-suburbs flight paths is causing such a problem, why not use it only for take-offs and landings over the bay?

This seems such an obvious solution.

With one simple operational change, all of the current issues with the new flight paths disappear, still with a net benefit to BAC and the airlines, and a huge benefit to tens of thousands of unhappy Brisbane residents!

We know that the old 01R runway was capable of handling all of the airport’s 2019 traffic—with few complaints—and almost certainly will handle all traffic growth until at least 2031, so having a second runway dedicated to over-bay operations would still be a significant boost, and would obviously help with noise abatement, traffic management and congestion avoidance for all flight paths in the right conditions.

So let’s ask the question again: why is the second runway—with all of its new and highly contentious over-suburbs flight paths—being used? It’s certainly not because the airport has to. Post-Covid, that is blindingly obvious to anyone; if the airport operated successfully with one runway in 2019 then it must be able to operate in 2020 at 40% of that capacity, still with a single runway.

So the only explanation is because the airport and airlines want to.

They want to, despite all of the noise pollution and protest and grief it’s causing.

They want to because twenty years ago they predicted they’d need it today, and even though with every passing year it has become more and more obvious it wouldn’t be needed by 2020, even now they’d rather ruin the amenity of tens of thousands of Brisbane residents for the next ten or fourteen years, totally unnecessarily, rather than make a simple change to their plans about how to use a runway they don’t actually need!

That’s not reasonable

The BAC Master Plan for the new runway stated (emphasis mine):

2.7.7 Key Assumptions


The following assumptions are key to the achievement of forecasts for Brisbane Airport: 

  • Economic growth will achieve the ranges suggested earlier in this section; 

  • Qantas, Jetstar and Virgin Blue will continue to serve the Australian domestic market; 

  • Airline supply side issues such as air services and airport capacity will not impede growth; and 

  • Airfares will fall modestly in real terms in the longer term and the higher airfares associated with the high fuel prices will abate before impacting significantly upon passenger numbers. 

It has been assumed that any ‘shocks’ associated with terrorism, health issues and other ‘unknown’ factors will have only short term impact such that passenger levels will maintain their steady growth rates throughout the forecast period. 

It is obvious now that more than one of these assumptions was incorrect, and it’s therefore no surprise that the projections on which they’re based are also incorrect, as BAC themselves pointed out—but subsequently ignored.

What is surprising, and disappointing then is that BAC and the airlines haven’t changed their planning in any way since 2003 despite that clear evidence, years ago, that their assumptions were wrong. Their projections fell well short by 2005, and further and further short by 2010 and 2015, as Table 1 clearly shows. In total they forecast a nearly 100% increase in traffic from 2000 to 2020, yet even before Covid that increase was clearly going to be less than 50%, but their plans still didn’t change.

It was perfectly clear that a second runway and its flight paths were not needed in 2020. Using their own projections, it was not needed until at least 2031. More recently still, since Covid, probably no earlier than 2034. However they’ve proceeded as though it is: they opened the runway after the pandemic struck and its consequences were obvious, and they’ve been using it as though all the new flight paths are needed, flying planes for the first time over long-established suburbs and parks anyway, when the runway and flight paths aren’t needed at all.

This is ridiculous and unnecessary. It would be foolish not to use the new runway now it has been built and commissioned, but at the very least operations on it should be curtailed to  only over-bay takeoffs and landings. That would still provide up to 50% greater capacity than the single runway configuration, and much more capacity than is needed for many years to come.

Yet not every resident in Brisbane will necessarily support this strategy, strange as this may seem.

Residents in Brisbane can be broadly divided into three groups: those who live under the old flight paths, those who live under the new flight paths, and those who don’t yet live under a flight path. The old flight paths have been in place since 1988, so anyone who moved under a flight path in the intervening thirty two years would have understood the choice they were making, and will have lived with the associated noise pollution ever since. In contrast, those under the new flight paths are all living in suburbs over which planes have never flown, and who would have bought there, possibly deliberately, believing that planes would not fly over them.

This proposal will mean that those residents who already live under a flight path will continue to live under a flight path, but for at least the next ten years, possibly much longer, those residents who didn’t live under a flight path will continue not to live under a flight path. So where is the problem?

The problem is that the government, BAC and the airlines sold the second runway strategy to residents already under a flight path by promising that they would suffer less noise pollution. What the aviation stakeholders failed to mention was that in fact they were really going to cause more noise pollution overall, and more importantly they were going to cause pollution for many more residents than before, including residents who had never suffered any aircraft noise pollution before!

It was clever, if deceptive marketing, selling an increase both in total pollution and in total residents affected by promoting it as a reduction, but in reality it was only a temporary reduction, and only a reduction for those people who had already decided to live under a flight path. It quietly ignored the protests and loss of amenity of all those people who hadn’t made that decision, and were suddenly, unilaterally going to find themselves under a new one.

It’s worth noting that this is entirely contrary to a resolution of the International Civil Aviation Organization, of which Australia is a member, where at the ICAO 39th General Assembly we all declared (emphasis mine):

The Assembly:
1. Declares[…] In carrying out its responsibilities, ICAO and its Member States will strive to:
a) limit or reduce the number of people affected by significant aircraft noise;
b) limit or reduce the impact of aviation emissions on local air quality; and
c) limit or reduce the impact of aviation greenhouse gas emissions on the global climate;v

Human nature being what it is it’s not surprising that some residents under the old flight paths are enthusiastic supporters of BAC’s plan simply because, temporarily, some of the pollution is going to be dumped somewhere else,and clearly they don’t care that it is going to be dumped on people who, unlike them, hadn’t knowingly bought houses under a flight path.

In this way the government, BAC and the airlines have colluded to pit suburb against suburb on the false premise that there had to be more pollution, and further it was “fair” that suburbs without pollution should now be polluted; changing the argument from “should there be more pollution spread wider and over more people?” to “is everybody sharing the pollution fairly?” A bizarre question, but there it isvi.

Having suburbs fighting with each other is obviously far preferable for the aviation industry than having all suburbs united against the polluting industry! In promoting the “share pollution ‘fairly'” argument the aviation stakeholders conveniently ignore an absolutely basic town-planning principle: that you segregate polluting industries from residential suburbs. If you increase pollution you don’t solve the problem by spreading the pollution “fairly” over even more people, but they have.

Using the new runway but using it only over the bay will instantly remove all of the new, unwelcome noise pollution from dozens of suburbs where it never was before and there is no need for it to be.

It will not reduce the noise over residents in suburbs that had the noise before, have been under flight paths and have known about flight paths for over thirty years and who have chosen to live there anyway. It’s worth noting though that, post-Covid, for these residents the number of flight movements is currently a fraction of 2019 levels, and it’s not expected to return to 2019 levels for four more years, so at least until then they will experience a reduction in noise anyway. It will also allow at least four years for more reasonable long-term solutions that actually reduce total noise pollution, not increase it, spread it around, and pretend it’s a reduction.

It’s a simple measure of the real impact of these unnecessary new flight paths that even with the significantly reduced post-Covid traffic, protests and complaints from the newly-affected suburbs have been significant and widespread. Contrast that with the much heavier pre-Covid traffic on the old flight paths over suburbs where people chose to accept the traffic, and where in 2019 there were practically no protests at all…

It’s also important to note that this proposal in no way dismisses the real concerns of residents under old flight paths, or suggests that we shouldn’t also pursue further efforts to reduce the pollution that they suffer—apart from simply spreading it around. For example, there are strong arguments being put forward that a change in tailwind rules would allow a useful reduction in over-land traffic regardless of which runway was being used, and using full runway length would likewise reduce over-land noise, so those proposals and others like them can and should be pursued in parallel to this one.

However this one—using the new runway only over the bay—will have an immediate and dramatic impact. It will instantly solve the unnecessary problem of the new flight paths, and just as importantly it will also allow at least ten years for real community discussion, real consultation and real consideration of a consensus solution to the overall problem of a noise polluting industry, one that is currently unnecessarily violating every town-planning principle and newly destroying the amenity of many Brisbane residents—with no need and to absolutely no purpose.

With thanks to Agnieszka, for originally pointing out the simple truth.

iMike O’Connor, “International Ideas Could Solve the Noise Problems,” My Village News November 2020 (blog), October 2, 2020, 9, https://myvillagenews.com.au/november-2020/.

ii“BNR_EIS_MDP_A2_Need_Background.Pdf,” fig. 2.6g, accessed October 22, 2020, https://www.bne.com.au/sites/default/files/docs/BNR_EIS_MDP_A2_Need_Background.pdf.

iiiBureau of Infrastructure and Transport Research Economics, “Airport Traffic Data,” Bureau of Infrastructure and Transport Research Economics (Bureau of Infrastructure and Transport Research Economics), pts. 1985–2019, accessed October 22, 2020, https://www.bitre.gov.au/publications/ongoing/airport_traffic_data.

iv“BNR_EIS_MDP_A2_Need_Background.Pdf,” fig. 2.4d.

v“Resolution_A39_1.Pdf,” accessed October 17, 2020, https://www.icao.int/environmental-protection/Documents/Resolution_A39_1.PDF.

viinfinite8horizon, “Michael McCormack’s (Un)Fairness Principle,” Infinite8horizon – Peter d Barnes (blog), October 18, 2020, https://infinite8horizon.wordpress.com/2020/10/18/michael-mccormacks-unfairness-principle/.

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