At the request of the Ministry of Infrastructure and Environment (IenM), we reviewed the noise calculations for various aircraft types for Lelystad Airport. Unfortunately, we found that an incorrect assumption was used in the noise calculations for one aircraft type, the Boeing 737. For this aircraft type, a lower thrust was used in the noise calculation for the approach routes, resulting in an underestimation of the noise effect of a landing Boeing 737. We have since corrected this error and recalculated the correct noise profiles for this aircraft type.
Based on the corrected calculation, the external research bureau To70, on behalf of the Ministry of IenM, made a new noise contour calculation around Lelystad Airport. A small change is visible in the so-called ’48 Lden contour’ between Biddinghuizen and Zeewolde. This means that the contour boundary will be less than a hundred meters further away. Following an initial analysis, it is expected that the effects of the corrected calculations will be very limited. Nevertheless, due to caution, the State Secretary will have it assessed whether the EIA for Lelystad should be adjusted.
We are fully aware of the importance of accurate noise calculations for air traffic in a densely populated country like the Netherlands. We regret that uncertainty has arisen about the calculations. We have adjusted the flight profiles so that the noise calculations can be redone with the correct data. Additionally, we will take measures to make future calculations even more critically evaluated before they are released. We will also review the externally commissioned verification process with research bureaus and submit proposals to the Ministry of IenM for improvement of the overall decision-making procedure.
Michel Peters
General Director NLR
