Cut Noise

Balancing the benefits and disbenefits of aviation


“For thousands of years, the exchange of culture, ideas, goods and services has been the powerhouse of human progress. Aviation has accelerated that exchange across continents, making a huge contribution to humanity and the global economy. International trade is responsible for much of the development and prosperity of the modern world”. Warren East, the chief executive of Rolls Royce, Daily Telegraph (4/2/20)

And flying has a central role to play in this globalised economy. There will be growth in aviation. Less than 10% of the world’s population has ever flown. As the emerging economies of the world grow so the number of people flying will increase. This will provide millions of people with new opportunities, increase prosperity and open up closed societies.

But flying and aviation also create noise, climate and possible land-take problems. Balancing the benefits and disbenefits is not easy. At least 2.5 million people in the UK are impacted by aircraft noise, according to government statistics.

For futher information on aircraft noise: 

The blogs in this section: 

Sound solutions to aircraft noise 

Electric Dreams

Why 'degrowth' is not the way forward for aviation

The case for a Frequent Flyers Levy 


Sound solutions to aircraft noise


When aircraft noise disturbs, it can really disturb. The chart (right) shows that only wind turbine noise annoys so many people at lower levels. Of course not everybody is disturbed by the noise. The statistics show that even at high noise volumes, a lot of people are not worried by the noise. This seems particularly to be the case when a person is born and brought under the flight path. I’ve spoken to people who have lived within couple of miles from Heathrow all their lives who tell me they are barely aware of the planes flying overhead.

If you are driven to despair by the noise, you can become very angry with the airport. Sometimes with good reason. Airports have often treated overflown communities in a very dismissive way. The exceptions stand out: somewhere like Vienna. In recent years, Heathrow, too, has pioneered many community initiatives. That anger can lead to fury with the aviation industry. And to become ‘anti-aviation’. That is utterly understandable. The despair of living with the noise can be overwhelming.

But the sheer anger of the disurbed can blind us to the good aviation can and does do good.

Aircraft are the work-horses of the globalised economy which has over the last few decades facilitated the trade which has lifted millions of people out of poverty.

I know Bjorn Lomborg, the Danish author of The Skeptical Environmentalist, is a controversial character but he is spot on when he wrote this last year:

“The most powerful thing governments could do to transform lives would cost next to nothing at all: embrace freer trade. During the past 25 years, China lifted 680 million people out of poverty through trade, and there are similar stories from Indonesia, Chile and others. Genuine, global free trade would have benefits that would reach every single country. Far more than any aid dished out by donor countries, lowering trade barriers is the most powerful way to reduce extreme poverty. A completed global Doha trade deal would make the world $US11 trillion richer each and every year by 2030 according to research considered by the Nobel laureates”(1).

Flying has also opened up travel to this generation in a way that previous generations, unless they were wealthy, could only dream about.

This is not to say that aviation shouldn’t pay more tax. It should. It is undertaxed. It pays no tax on airline fuel and there is no VAT on tickets. I favour a Frequent Flyers Levy. 

And it makes sense to encourage rail to be convenient, reliable and affordable so it becomes the mode of choice for shorter journeys. It is quieter and cleaner.

But we mustn’t kill off aviation. The focus should be on dealing with its downsides. I actually believe that dealing with its emissions – and CO2 emissions from aircraft are significant – will prove easier than sorting out the noise it causes. Unless and until we have cleaner fuels, it is perfectly possible to require other sectors of the economy to decarbonise further in order to allow some growth in aviation – remember less than 10% of the world’s population has ever flown and, as the emerging economies become richer, their peoples will fly much more than they do today. 

So, how to we deal with noise?

1.Research and development into quieter aircraft. Aircraft are a lot less noisy than they were 40 years ago. But in the coming years an annual reduction of only 0.1% is expected in noise from aircaft coming on-stream. The technology is not on the horizon for planes to get significantly quieter anytime soon. Meaningful resources need to be put into research and development in quieter planes by both the industry and governments. And this R&D should not take second place to the development of planes which emit less CO2.

2. Build new airports well away from centres of population. It is interesting there are few noise complaints about the main airports in the Scandinavian countries. They are located well outside the towns and cities. It is not always possible to relocate existing airports but there are lessons here for the emerging economies as they build new airports. (Wherever an airport is built people who lose their homes or land should be generously compensated).

3. Encourage quieter alternatives to air travel where feasible.  Aviation does long-distance journeys well but, if rail became more viable for shorter journeys, there opens up the possibility of managing or even reducing flight numbers over communities which is what they want above all else.

4. Share the noise around. Except for areas under the final approach to a runway, it is perfectly possible to use new technology to create multiple flight paths and to rotate them so as to give residents a break from the noise each day. In my experience communities are much less interested in how many runways an airport has than in how many planes fly over their homes. These days it is the volume of aircraft passing overhead rather than the noise of each plane that is the biggest cause of disturbance. This sort of respite should also be a no-brainer for the industry. It allows it to expand while limiting flight numbers over most communities.

5. Limit night flights. The European Union published a report which showed that, world-wide, most night flights were operated for the convenience of the airlines, rather than because they were essential (2). Night flying should become the exception.

6.  Provide generous compensation and mitigation. Communities under flight paths should expect money to pay for effective sound insulation measures. People who lose their homes or who see them devalued in price should be properly compensated.

7.  Ensure best operational procedures are followed. The steepness of the descent or ascent is important for communities as are measures such as when aircraft coming into land lower their landing gear.

These measures would quite noticeably lower the impact of noise.

John Stewart



(2). Assessing the Economic Cost of Night Flight Restrictions, European Commission 2005

Graphene based material could reduce aircraft noise

This article first appeared in The Engineer 18/6/21 

A ‘meringue-like’ graphene based material could reduce aircraft engine noise by up to 80 per cent, claim researchers at Bath University.  The graphene oxide-polyvinyl alcohol aerogel weighs 2.1kg per cubic metre, which is said to be the lightest sound insulation ever manufactured. The team believes that, when used as insulation within aircraft engines, noise could be reduced by up to 16 decibels. This would take the 105-decibel roar of a jet engine to a sound closer to that of a hair dryer.

With a ‘meringue-like’ structure, the extremely light material could act as an insulator within engine nacelles with almost no increase in overall weight according to researchers. The team is working on further optimising the material to offer improved heat dissipation, offering benefits to fuel efficiency and safety. Researchers from Bath’s Materials and Structures Centre (MAST) have published a method for manufacturing the materials in the journal Nature Scientific Reports. 

 “This is clearly a very exciting material that could be applied in a number of ways — initially in aerospace, but potentially in many other fields such as automotive and marine transport, as well as in building and construction,” said Professor Michele Meo, research leader. Meo said that the team managed to produce such a low density by using a liquid combination of graphene oxide and a polymer, formed with whipped air bubbles and then freeze-casted. “On a very basic level, the technique can be compared with whipping egg whites to create meringues — it’s solid but contains a lot of air, so there is no weight or efficiency penalty to achieve big improvements in comfort and noise,” Meo added.

Whilst the initial focus is on working with aerospace partners to test the material, the team said it could also be used to create panels in helicopters or car engines. Researchers estimate that the aerogel could be in use within 18 months.

Electric Dreams

Electric Planes could be here sooner than we think but what will they do for noise…..

In less than 20 years electric planes could be using our airports. A new report (1) from the CAA (Civil Aviation Authority) suggests some short-haul flights could be using electric aircraft by the early 2030s. However, the larger long-haul planes are not expected to be electrified until at least 2050. Electric aircraft would reduce the air pollution and climate emissions coming out of each plane. But there is much more doubt about their noise benefits.

The report says “There is still a clear need to undertake noise measurements of the full scale commercial electric planes once they are available to fully understand their noise characteristics” adding “it is still unknown whether the noise exposure from electric aircraft will be an improvement from conventional aircraft.”

The CAA report identifies the main sources of the potential noise from a fully electric plane: the battery systems, the motor and air frame. Early modelling suggests the planes may be quieter on departure than current aircraft but noisier on arrival. But, because of their batteries, they will be heavy and are expected to climb more slowly after take-off which might off-set any noise gains at source. All of this would be problematic for communities under flight paths. The technology which could clean up the industry could make things worse for them. They will be concerned that, driven by the need to cut emissions, the aviation industry may rush into a technology which may do little or nothing for noise.

Another key report (2) came to similiar conclusions:  "Considering both takeoff and landing operations, a 36% reduction in noise contour area is estimated.  During takeoff, aircraft noise is mainly determined by the thrust of the engines required. Owing to lower fan pressure ratios and the absence of combustion noise, we anticipate a more than 50% reduction in takeoff noise contour area. In contrast, during landing, the higher weight of all-electric aircraft means that the determinants of noise (principally lift, drag and landing speed) will result in a 15% larger noise contour area compared to those of best-in-class narrow-body aircraft.

Developing new aircraft, whether or not they are electric, often means noise and emissions are at odds with each other. It’s a tough challenge for the aviation industry which aims to develop technologies and operational practices which will reduce aircraft CO2 emissions per passenger kilometre by 75%, noise by 65%, and NOX by 90%, by 2050, benchmarked against a typical new aircraft in 2000. The industry body Sustainable Aviation says (3): “Achievement of any one of these three targets would be challenging, but to achieve all three simultaneously will require considerable ingenuity and a clear understanding of the inter-dependencies between these three key drivers”.

The CAA summed it up like this (4): “Concerns in relation to climate change, carbon dioxide emissions, and local air quality could also have an impact on noise performance. Although there is not a direct correlation, and noise performance has previously been reduced alongside emissions reductions, as gains become more marginal in future, the potential requirement to trade off emissions and noise performance is likely to increase……the Sustainable Aviation Noise Roadmap 22 for example, highlights that there are two conceivable paths for future aircraft design, low-carbon designs and low-noise designs. Whilst low-carbon designs may be quieter than existing aircraft, they may not be as quiet as low noise designs”.

Given the potential conflict with CO2 is essential a noise audit carried out on each new aircraft design. 







Why 'degrowth'​ is not the way forward for aviation


I simply can’t buy the argument that ‘degrowth’ is the way forward for aviation. Indeed, I believe it is positively harmful. Implemented, it would take away any chance of millions of people across the world climbing out of poverty and getting a better standard of living.

It has been described thus:

“degrowth is about much more than just a simple decrease in consumption, living standards or material throughput of the economy. The concept also encompasses a critique of the whole modern culture of development, that is, a belief that more is always better. A core concept is sufficiency”.

Tell that to the family in Africa on the breadline, desperate to make ends meet. Tell that to my facebook friends from Uganda who are desperate to learn and better themselves but who are struggling just to pay the fees to go to school.

Bjorn Lomborg, the Danish author of The Skeptical Environmentalist, wrote this last year:

“The most powerful thing governments could do to transform lives would cost next to nothing at all: embrace freer trade. During the past 25 years, China lifted 680 million people out of poverty through trade, and there are similar stories from Indonesia, Chile and others. Genuine, global free trade would have benefits that would reach every single country.(1).

And a growing and successful aviation industry is critical to delivering free trade in a globalised world.

I would ask anybody who backs the degrowth of aviation to read this article:

It argues that “the largely empty African skies have a tangible economic impact on the people below”; that the economies of the planet’s poorest continent are missing out on more than a billion dollars in possible growth because of poor air connections. Africa needs better air links; more airports; lower fares. Any significant increase in carbon emissions can be compensated for by reductions elsewhere.

The bigger concerns about such expansion are its potential impact on people’s land and the noise communities will experience. There have been horror stories across the world of people’s lands and homes being seized with little or no compensation. And the noise from the planes will be a huge problem for people who haven’t experienced it before.

The answer must be to learn the lessons of Europe and to build the airports as far away from populated areas as possible; to buy out, at a fair price, anybody still impacted by the noise; and to factor in operational measures which benefits communities, such as respite, from the start. These are the issues we should we should be concentrating on.

How can we get expansion in the emerging economies of the world while minimizing the downsides? It’s a challenge for governments and for the aviation industry. It’s where campaigners should be putting their energy. ‘Degrowth’ has next-to-nothing to say about this.


John Stewart

The case for a Frequent Flyers Levy


It’s common when you suggest more tax on aviation to be branded anti-flying. And it is perhaps not surprising. There are environmental campaigners who seem to have a visceral hatred of aviation. Or at least the way they talk about taxing flying gives that impression. l

It’s pity because it rules out sensible debate. There is an argument for aviation to pay more tax. However, it is not enough to cite the mantra that simply because airlines get tax-free fuel and there is no VAT on tickets, taxes should go up. That is putting on a tax for the sake of taxing. Not a good or rational idea!

The reason I think the industry should pay more tax is that it is a way of managing demand which I believe is needed to limit flight numbers over communities. This is less critical in countries where aviation is in its infancy but important in places like the UK, most of Europe and in America.

The tax has to be fair: fair to communities, passengers and the industry.

I’m not suggesting it is viable or fair to impose any additional taxes on the industry while it is on its knees. But in due it will recover and the overflown will need some protection.

I favour something like the Frequent Flyers Levy, but with one important addition: that the tax raised is earmarked for research and development into quieter and cleaner planes.

The essence of the Frequent Flyers Levy is this: each person is entitled to one tax-free return flight each year but the tax rises with each subsequent flight taken. Most people would be better off than under the present system where we are all charged air passenger duty.

The little-known fact is most people hardly fly at all. Even though Brits fly more on average than any other country, more than half of us took no flights at all last year (2019). 22% took one return flight, and 11% took two. That leaves just 15% of the population take 70% of all flights.

The research shows that a Frequent Flyers Levy would cut demand but still allow ordinary working families the chance to fly off on holiday. The other thing that is important is that the tax is imposed on the number of flights taken rather than the distance travelled. That may not be ideal in climate terms but that, in my view, is outweighed by fairness. It allows us to occasionally visit the far-flung corners of the earth and also doesn’t penalise people who want to visit families and friends.

In noise terms it works. Aircraft noise is only a problem as planes descent to land then take-off. In noise terms, it is not relevant how far the plane flies. They key thing is to manage the number of aircraft.

How could it be imposed? In a nutshell, two significant changes would be needed to the way things work at the moment. First, HMRC would need access to data that is already captured by the Home Office, on passenger movements in and out of the country. This would have to be stored in an automated database that airlines could access in real time when selling tickets to customers. Second, airlines would need to start recording customers’ passport numbers at the point of ticket sale - instead of before boarding as is currently the case.

Given the tax is workable and fair, it is not surprising that a growing number of politicians across Europe are interested in it. I see it as a realistic way to help ease the practical problem of too many flights going over airport communities. Let’s talk about it and discuss it in that light. Not as a tool to bash the aviation industry.

John Stewart