Originally Posted by
Fairdealfrank
As it was explained to me at a Heathrow public consultation in Richmond, with three rwys, one is for takeoffs, one for landing and one for both. This would rotate through the three rwys over a three day period.
Close, but no cigar.
The proposed alternation scheme would have four, rather than three, phases.
The reason is that the centre runway (the current northern one) can't be used in mixed mode for ATC reasons, so it would continue to operate in segregated mode with landings 50% of the time and takeoffs the other 50% (as at present).
The proposed new northern runway and the current southern one would operate in mixed mode 50% of the time, segregated arrivals-only mode 25% of the time and departures-only mode the remaining 25%.
So the Arrivals/Mixed-mode/Departures pattern would look like
09L/27R: M D A M
09C/27C: D A D A
09R/27L: A M M D
I don't recall seeing any statement about how frequently the runway roles would switch, it might well be daily but other options including the current 3pm changeover would obviously be feasible as well.