Finding the sweet spot: Optimising air travel for noise and fuel consumption

As the aviation industry seeks to balance environmental concerns with operational demands, noise pollution remains a pressing challenge, particularly for communities near airports. The DYN-MARS project, funded under the Horizon Europe framework and supported by the SESAR JU, is exploring innovative solutions to reduce noise and fuel consumption during aircraft descent and approach.

In this interview, Jean-Marc Wunderli, head of the Laboratory for Acoustics and Noise Control at Empa, Switzerland, is bringing his expertise to the project. With decades of expertise in aircraft noise modeling and assessment, Mr. Wunderli shares insights into the current state of noise pollution, the role of advanced flight procedures in mitigating its impact, and the contributions of DYN-MARS to creating a quieter, more sustainable aviation future.

Mr Wunderli, could you please describe the current noise pollution situation?

The European Environment Agency (EEA) reports that around 3 million people are exposed to day-evening-night noise levels (Lden) of 55 dB or higher during any 24-hour period, according to their EEA Report No. 22/2019. Although this number is much smaller compared to the 113 million affected by road traffic noise, aircraft noise causes significantly higher levels of annoyance at the same exposure levels. Moreover, aircraft noise is concentrated around airports, intensifying its impact on nearby communities.

In 2018, the World Health Organisation released noise guidelines that are much stricter for aircraft noise (45 dB Lden) than for road traffic (53 dB Lden) to help prevent negative health effects. As a result, many airports face strong political pressure to reduce noise, potentially leading to limits on the number of flights or restrictions such as night flight bans.

While aircraft departures generate the highest sound pressure levels on the ground due to high thrust settings, technological advancements over recent decades have significantly reduced engine noise. Attention is increasingly shifting toward noise generated during arrivals, where airframe noise often dominates. This is why DYN-MARS is looking into optimising flight procedures during descent and approach as this offers substantial potential to reduce both noise and fuel consumption.

How is the DYN-MARS project addressing these challenges to reduce noise pollution?

DYN-MARS builds on the research from our previous DYNCAT project, where we developed strategies to reduce the environmental impact of jet aircraft during descent and approach. In DYN-MARS, we are advancing these strategies by integrating them into a comprehensive air traffic management system. This includes providing additional information to both air traffic control and aircraft crews, as well as enhancing data and information exchange between ground - and onboard personnel and systems. These improvements enable the full potential of the optimised approach techniques to be realised.

What is Empa's role within the project and what are you currently working on?

In the DYN-MARS project, Empa focuses on noise calculations to assess the potential benefits of the solution compared to reference scenarios. Using our aircraft noise simulation tool, sonAIR, we model ground-level noise exposure based on the aircraft's position, configuration, thrust, speed, and ambient air density.

Currently, we are enhancing our simulation by adding perception-based acoustic metrics to better gauge the impact on communities. The next steps will involve factoring in population distribution data and projecting short-term reactions, such as annoyance and sleep disturbance from individual overflights, to long-term noise exposure. Once these improvements are made and tested, we'll move on to the validation exercises.

As an expert on noise, what are your hopes and future perspectives for the reduction of noise pollution in aviation?

Alongside DYN-MARS, several ambitious research initiatives have recently concluded or are currently underway, such as projects on alternative aircraft concepts (like ARTEM) or engines with improved fuel efficiency and noise reduction (e.g., EXFAN). I am confident that these efforts will drive innovations to further reduce aviation's environmental impact.

For short- and medium-range flights, turbo-prop aircraft are expected to gain importance. While they generally produce lower overall noise levels, they have distinct tonal components that can be particularly irritating. The challenge ahead lies in acoustically optimising these propulsion systems to minimise noise disturbances.

More about DYN-MARS: https://www.sesarju.eu/projects/DYN-MARS

*What is Empa?

Empa is an applied research institute within the ETH domain in Switzerland with a focus on materials science and technology. The laboratory for Acoustics / Noise control has a long tradition in measuring and modelling aircraft noise and assessing its effects on the population. In their efforts to contribute to reducing the noise problem, Empa supports their DYN-MARS partners in the development of low-noise flight procedures.

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