Sustainable aviation critical for reducing the average noise footprint

Given the alarming numbers, it was early in 2013 that the United Nations introduced a standard for noise reduction which recommended that the noise decibels were lowered by 7 decibels. The WHO recommends that noise is reduced to below 45 dB during the day and 40 dB at night. The industry has been quite persistent in working to reduce noise, with significant progress technologically, and it has been modestly successful over time. The noise levels have halved in the past 10 years and if the statistics are right, each new generation of aircraft is at least 15% lower than previous models.

The number of people exposed to aircraft noise around the world was reduced by 35%. ICAO advocated a balanced approach to noise reduction which is a combination of noise reduction at the source with land-use planning and management, operational improvements, and flight restrictions. The aim is to maximize the environmental benefit while minimizing cost.

Pre-pandemic, there were fluctuations and there were massive ups and downs. Should we look at the leaders in the market, the otherwise large Boeing 787 and Airbus A380, have remarkably small noise ‘footprints’. The new Bombardier CSeries is said to make use of Pratt & Whitney ‘geared’ turbofan engines, which further eliminated noise.

It is no small secret that while efforts are being made to bring down the total noise pollution, with the growing volume of air traffic (both passenger and cargo) the overall figures will keep increasing. Most of this growth has occurred in emerging economies, as they begin to reap the benefits of air travel.

Research into noise reduction has included parameters like the amount of air traveling through the engines, the average size of the fan blades in the engine, the position of the engine on the aircraft body, and even the size and number of flaps that help control the wing shape. While this may seem a lot mundane (after all who would imagine getting down to technical details after paying for that flight ticket!) the truth remains that these are quintessential for more sustainable aviation.

It is noted that the two key sources of aircraft noise are engine noise and airframe noise and the introduction of new types of engines, acoustic liners, and noise technologies has helped to reduce engine noise significantly.

Airbus’s A320neo for example has a new engine with improved aerodynamics that helps to curb noise. The upgraded version has reduced noise by 50 percent when compared to an earlier model.

The aviation industry is serious about its commitment to sustainability with Boeing and NASA working in sync to see how soon they can eliminate noise pollution. They have conducted special test flights on the 777 to generate acoustic maps with noise reduction.

Limitations when it comes to aircraft noise management mean that the antiquated airspace means dated design and technology that may be ill-equipped to manage noise pollution currently.

Developments in technology mean some aircraft are capable of flying using alternative approaches - steeper, shallower, and in a curve to name a few - but are limited by airspace.

Aircraft certification processes do involve noise assessments, and today's planes are 90 percent quieter than before. However, the rate at which change happens isn’t always at the speed that afflicted communities would like. People don’t want to wait for years to get a response.

While the noise pollution levels have been managed to a great extent, it is equally true that locals who have suffered over time were almost getting used to lesser noise levels during the pandemic.

With all of these realities playing out concomitant with the growing need to fly more, it is imperative for the rational mind to conclude, ‘There’s sometimes only that much one can do!’