Activist groups block more than just highways. They generate a lot of media attention, but with their associated dogmatic positions they also block possible solutions for the -indeed- very real problems. See the shutdown of the last nuclear power plants in Germany, which -according to the Washington Post- leads to more than 20 million tons of extra CO2-emissions per year. Five times as much as the emissions from all business jets in all of Europe. Then again, actions against business jets are of course also mainly about perceptions and media attention. And it is easy. You don’t have to spend time looking for facts and doing analyses.


Creating perceptions is effective. Attempts by the Dutch government to force downsizing of Schiphol Airport are mainly the result of perceptions. The aim, the government stated, is to limit sound annoyance. However, downsizing only leads to a small reduction in sound exposure. And we know that even a large reduction -such as the 50% reduction during the COVID-crisis- did not lead to less, but to even more sound annoyance. Not surprising, because sound exposure is measured and enforced via the Lden, which is an average per 24 hours over a year. That has little to do with how people experience sound. Again, not surprising, as that measure was originally developed for land-use planning, to assist with zoning measures, and not for preventing individual annoyance.


The fact that limiting sound annoyance requires policies in addition to limiting sound exposure is by now common knowledge. Important elements are open discussions and consultations about options with communities around airports. Standard advice is to look for people that want to share their stories, to really listen to what they have to say, to what causes them to experience sound annoyance, and then to really see what can be done to reduce that annoyance. But here we encounter the main problem. Activist groups in the Netherlands dogmatically cling to that average exposure as the only option. They even go to court to enforce average exposure limits*. As ineffective as these are to prevent annoyance at the levels we are looking at.

Moreover, using misinformation campaigns, they actively encourage distrust of the aviation sector. A standard part of these campaigns is to blame Schiphol Airport and KLM for causing the growth of aviation. But aviation is not a product. It is infrastructure and, as with other infrastructure, increased use is driven by economic growth. Thus, by society’s need for mobility. Not by an airline and certainly not by an airport. These are service providers, just like railway companies and railway stations are. But that accusation creates a big problem. An open dialogue no longer appears to be possible for lack of trust.


Yet there is hope, as is indicated by an analysis of the complaints about Schiphol Airport. These complaints are registered and analyzed by BAS, an independent organization with an informative website. According to their 2022 report, more than 340,000 complaints were received that year, from 10,606 people. Of those people 85 were responsible for almost half the reports: 167,153. So, the distribution within the dataset appears to be quite lopsided.

On top of that, the distribution within that group of 85 is also very lopsided. Ten people account for almost half of the complaints in that group: 78,399. And within those ten, one individual filed almost half of their complaints: 34,898. More than 10% of the total number of complaints. By the way, that person lives in the city of Nijkerk, almost 50 km distant from Schiphol. Which confirms that factors other than sound exposure can also be a big source of sound annoyance.

BAS ultimately decided to limit the analysis to a focus group: people with 500 reports or less. The average number of reports per member of that focus group was 16, twice as many as in previous years.


This raises two questions. First, the initial quick analysis above revealed that the data set is quite lopsided. So, using an average is rather useless. If ten people earn 100,000 euro per year and an additional one earns 10 million, then the group average is 1 million per year. Which tells you exactly nothing. Secondly, why set the cut-off point at 500?

A standard box-and-whisker analysis provides more insight. The procedure starts by ranking the reporters based on their number of reports, from low to high. Then find the number of reports from the reporter at the halfway point, the median. In this case, person number 5303. That number is two. So, 50% of the reporters submitted two reports per year or less.

The next step is to determine the number of reports from the median of the first half, reporter number 2652 (Q1), and the median of the second half, reporter number 7954 (Q3). That is one and eight. So, 75% of the reporters submitted eight or fewer reports. Finally, the upper limit is determined, the cut-off point, and thus the outliers. These are probably highly noise-sensitive people or – in the higher echelons – activists and you will not help them with consultation. The usual formula is Q3 + 1.5(Q3-Q1), so 8 + 1.5(8-1), so 18.5. That covers 84% of the dataset, almost 9,000 people, each having filed 18 or fewer reports, with an average of just over three reports per person.

Broader Policy

That group would be a likely candidate for follow-up discussions. This could well be people who are interested in solutions, and this should allow for an open dialogue. A possible approach could be to have individual conversations, analyze what is causing an individual’s complaints and see what can be done to reduce annoyance. For possible policy options, see the video and the PDF in the post ‘Senseless shrink‘.

But there is a second group, that might be even more interesting to focus on than the first group. Because you can do a further box-and whisker analysis of the outliers. Starting with their own median. When you do that, a new group of outliers pops up. The data turn out to be so lopsided that a total of four iterations of this process is needed to cover the total set.

The result is interesting. The four emerging groups are quite homogeneous, far more so then the total dataset is. As is indicated by the fact that the median and the average in each group are quite close. Moreover, both characteristics increase by approximately an order of magnitude per group. So, not group 1, but group 2 – with 1,526 individuals – might be the best candidate for the first conversations. They file quite a few reports, so they are involved, but they file less than 300 per year. They are therefore probably not noise-sensitive people, nor members of activists-against-aviation groups. They could benefit from targeted measures and might be open to honest conversations about options.

In addition, policy makers should also look at the 2.2 million non-complaining people who also live in the area the complaints come from. A good number of them might have no problem with living in the neighborhood of an airport. Analysis of what is of interest to these people may offer valuable policy options too. Both the video and the PDF contain a practical example: plan Kronenburg. A former industrial site in the middle of the city of Amstelveen, that could be redeveloped for much-needed student housing. Which is not possible now, due to zoning issues that cannot be resolved under the present sound exposure policy.

The Problem

The problem, of course, is that such conversations are pointless when activist groups and politicians continue to cling to average sound exposure as the only relevant benchmark. This tenacity is understandable from activist groups. It gives them a legal instrument*. But not from politicians. Unless, for some politicians, the real goal is not to solve problems, but to downsize Schiphol Airport. Whereby collateral damage -such as demise of the 104-year-old KLM and its network- is accepted, and might by some politicians even be welcomed. More about this in a next post.

* At least in the Netherlands, as it is one of the very few European countries, possibly even the only one, that has laid down Lden sound exposure limits in law, which can therefore be enforced by going to the courts. Thereby denying politicians and communities the option of balancing pros and cons and denying the application of additional policies not laid down in law.

Source of the data: BAS (Bewoners Aanspreekpunt Schiphol), Annual Report 2022, plus an anonymized dataset of 2022 provided by BAS upon request, for which many thanks. The numbers used in this post are taken from that dataset and differ slightly from the numbers in the annual report. This deviation has no influence on the analysis.