Sky Score

What this is: DEFRA Strategic Noise Map (Round 4, published 2022), the long-term average aircraft noise around LHR, LCY and LGW - modelled from a year of actual flight tracks, not a live feed. That year is 2021, when COVID restrictions held air traffic far below normal, and DEFRA describes the Round 4 result as a highly anomalous situation. Measured, they understate it by about half: DEFRA's 2021 Heathrow 55 dB contour covers 75.6 km², and the CAA's own model of 2024, a normal year, covers 148.4 km². The two are different models, so read that as an order of magnitude, not a correction. Round 4 is still the latest official round; the Environmental Noise Directive requires mapping every five years, so Round 5 falls due in 2027; DEFRA has not published a date. Used by councils for planning decisions. The overlay shows DEFRA's modelled contours; a postcode search gives a 0-10 quiet score for that location, not a decibel reading. All levels are outdoor, at the building's facade: indoors, with the windows shut, it is quieter, though gardens, balconies and open windows are not.