Originally Posted by
suninmyeyes
Heathrow do not use 09L for departures unless extreme circumstances.
Takeoffs from 09L happen mostly when delays push late-running departures into the night-time single runway operations period, where there is a 4-week runway rotation (subject to the wind). For example there were 10 late night departures from 09L on 20th January.
They occasionally have parallel arrivals in the busy spot after 6 am.
Parallel arrivals happen between 6 am and 7 am pretty well every day. It's the only way ATC can get through that hour without significant arrival delays building up.