Does anyone know why mix-mode isn't used at Heathrow?
The runways are used in mixed mode before 7am, however due to the massive number of houses under the flightpath, to give them a degree of respite from incessant heavies over their houses, the landing and departure runways are switched at 3pm when landing to the West. Until yesterday, this did not apply on the other end when landing was always on 09L and departure on 09R. This was known as the Cranford agreement, which Geoff Hoon announced yesterday was being abolished. Hence landings and departures will now swap over at 3pm when landing to the East in the future.
It is NOT an issue of the runways being too close together as you can see 747-400s shooting the approach in parallel most days.