You can see exactly where planes inbound to Heathrow go using this link: here. You may have to download some software before it works, and it only seems to work in Internet Explorer. By the time planes for Heathrow get to us they are receiving directions from a radar controller to line them up at suitable intervals onto the Instrument Landing Systems for Heathrow (or City) and are not using radio beacons to find their way. A lot of flights to both Heathrow (if landing to the west) and City (if landing to the East) do come directly over Forest Hill - but, as has previously been stated, they are not nearly as low, or noisy, as when they are closer to their landing points.