Simulated results for a transport aircraft following two different approach procedures. A conventional approach procedure and the new Helical Noise Abatement Procedure (HeNAP) have been simulated for comparison. Both flight trajectories with corresponding fuel consumption and time taken are depicted in the upper part. Predicted ground noise levels (maximum sound pressure level) are presented in the lower part of the picture. The dashed isocontour line shows the 66 dBA level footprint along the conventional approach whereas the coloured footprint shows the HeNAP. The aircraft along the HeNAP can remain at a higher altitude for most of the flight path, compared to a conventional approach. This results in significant ground noise reduction along the trajectory until the helical flight segment is reached. High noise levels are relocated and concentrated into an area around the helix. Obviously, a trade-off between a significant noise reduction and increased fuel consumption and flight time becomes inevitable.