When Environmental Resources Management, ERM, was preparing its report on public safety zones, it consulted with the local authorities in question a number of times. During those consultations, which took place over a period of about one year, ERM have advised that they used a number of different maps that were shown to the local authorities.
ERM have advised that as the study was progressing, both the mathematical modelling and risk analysis being used by ERM to determine the public safety zones, as well as the flight movement data being used in its analysis, were being refined. Therefore, while the approximate shape, size and position of the public safety zones was becoming clear, their precise delineation on the maps being used by ERM was subject to change.
As part of their public consultation process before finalising their report, ERM published details of the sizes of the public safety zones it was proposing, along with details of how it arrived at those particular zones.