The Antrim Area Plan 1984-2001, published in 1989 by the Department of the Environment for Northern Ireland Town & Country Planning Service is, as you can probably imagine, a rather dry report. But the black outline on this map from the report is interesting. Is it a bird? Is it a fish? I think it is a cross between the two, making a dive for the waters of Lough Neagh.
In reality the contour lines demarcate areas of noise pollution around Belfast International Airport. According to the report the “Noise and Number Index (NNI) contours were calculated using a complex formula which takes account of estimated growth in traffic, assumptions about the types of aircraft in use, and aircraft flight paths.”
The outer black line is the zone between 40 and 50 NNI. Structures, even houses, can be built within it but it is recommended that they are sound insulated. The areas of red-line hatching sticking out from each end of the runway are Pubic Safely Zones. There was to be no building of any sort within these areas. Take-offs and landings, as we all know, are the most dangerous parts of flight.