And, if too many aircraft cause safety issues on any particular route, there's always potential for it to be closed. Remember the bit of H2 that used to follow the M4 from LHR into town? It was deemed separated from the 27L/R approaches but too many issues of aircraft not flying the route accurately (even setting off down the A4 instead of the M4!) and getting a bit too adjacent to LHR landing traffic led to it being withdrawn.
In places you really are in quite close proximity to LHR traffic, certainly less than what should otherwise be 'standard' separation. You really do need to fly the routes as accurately as possible, both laterally and not above the 'not above' altitude.
Cracking views of London though
