HEATHROW AIRPORT Year 2015 Actual Modal Split (78% W / 22% E) Average Summer Day (0700-2300 BST) 57-72 dBA Leq Noise Contours © Crown Copyright and database right 2016. Ordnance Survey Licence number 100016105 0 2 4 6 8 10 km 57 60 63 66 69 72 72 69 66