Aircraft noise modelling: migrating INM to AEDT

The Integrated Noise Model (INM) used in Australia for modelling aircraft noise has reached its final iteration and is due to be replaced over the next few years. Some differences in how noise contours are modelled in the newer AEDT application will require careful management by policy-makers, regulators, airport operators, airport planners, and noise consultants alike.

[blockquote text=”Differences can be nuanced and difficult to explain in non-technical terms” text_color=”#004361″ show_quote_icon=”yes”][vc_separator type=’transparent’ position=’center’ color=” thickness=’5′ up=” down=”]

Explaining the differences

Over the next few years, Australia will be using the Aviation Environmental Design Tool (AEDT) to replace the legacy systems currently used to model aircraft noise, fuel burn and emissions. The primary focus will continue to be the noise modelling aspect, although the streamlined input process for both noise and emissions data into AEDT may make it more viable for stakeholders to perform dual noise and emissions studies.

The AEDT software improves upon key noise modelling algorithms using formulas based on more recent research and real flight data. Migrating from INM to AEDT will, however, bring some challenges on the road ahead for Australia’s policy-makers and airport operators and planners.

Differences in models present a potential for variations in the dimensions of contours and forecasted impacts of aircraft noise, and these differences can be nuanced and difficult to explain in non-technical terms. Stakeholders will need to understand the differences and explain the rationale behind them to manage feedback from communities that live near airports.

Improved noise modelling

An advantage of AEDT is that it uses more data points to assess flight profiles as well as the optional use of more highly detailed weather databases to allow for variation by position or altitude. In addition, the technical architecture makes better use of modern processors and streamlines the input processes to enable both noise and emissions modelling from shared data input. This reduces duplication, creating a better value proposition for airport owners and operators.

Certain modelling changes under AEDT are likely to have a small but discernible impact on the size and shape of current aircraft noise contours. These changes include adjustments to algorithms for lateral attenuation based on engine location, additional weather modelling requirements around atmospheric absorption of aircraft noise, and software tweaks for receptor grid generation and contour production.


Visualising noise contour changes

Like most airports around the world, Australia’s airports focus on two important aspects of aircraft noise – the impact on existing communities (e.g., complaints and activism, public and local government relations) and the impact on land development (e.g., land-use strategy, safeguards, policies). Changes to aircraft noise models and the resulting noise contours will present some challenges.

Over the coming months, To70 Australia will be mirroring INM models in development in AEDT. The AEDT outputs will be useful for reviewing and benchmarking an airport’s results against the current and previous INM-based models. Being able to compare the two can provide an appropriate context to help all stakeholders understand – and explain – the changes, and to appreciate the increased functionality and accuracy that modelling with AEDT makes possible.

In our presentation at the AAA Conference in Brisbane on November 14th, we gave a broad overview of what to expect from the migration from INM to AEDT, explaining the rationale, notable differences, potential outcomes and a tentative timeline. You can download a copy of presentation here (link to downloadloadable presentation). Contact our offices if you’d like more information.

Photo by Eva Darron on Unsplash


About To70. To70 is one of the world’s leading aviation consultancies, founded in the Netherlands with offices in Europe, Australia, Asia, and Latin America. To70 believes that society’s growing demand for transport and mobility can be met in a safe, efficient, environmentally friendly and economically viable manner. To achieve this, policy and business decisions have to be based on objective information. With our diverse team of specialists and generalists to70 provides pragmatic solutions and expert advice, based on high-quality data-driven analyses. For more information, please refer to


3 thoughts on “Aircraft noise modelling: migrating INM to AEDT

  1. Great article! Very little has been said here about the exact relationship between INM (IFAA’s ntegrated Noise Model) and AEDT – are you talking about the same models? & if so Is the presentation given on November the 14th available anywhere?

    Kathy Coffin
    Airspace Regulator (Environment)

Leave a Reply

Your email address will not be published.

© Copyright To70 2021