Sarah, with due respect, the original post explains why, although at some length. Basically there are 2 parallel runways at Heathrow, 27 left/09 right and 27 right/09 left. '27' denotes the orientation of the runway - in this case 270 degrees, which is due west. Aircraft need to land and take off into the wind, as far as possible. The prevailing wind over the UK is from the west, which means that for about 70% of the time aircraft will line up over and head over west London to land on either 27R or 27L. On the days when the wind is from the other direction they come in over Berkshire and the Windsor area (actually right over Windsor Castle, which prompted an American visitor to ask 'gee, why did they build the castle right under the flightpath?')! Because there are 2 runways, parallel, about 1/2 mile or so apart laterally, the landings can usually be alternated between the 2, thereby giving the residents directly under (in my case 27R) a rest for half of the day. The alternation days change from week to week, but the time is roughly from 04.30-15.00 for 1, then 15.00 - 23.30 for the other. In other words, for the 70% of the time when landings are over our way, each runway will be used for half the day.The problem at the moment is that because they are working on the adjacent taxiways to 27L/10R, they are not suitable for landing (possibly because there is a lot of plant and equipment nearby which would be hazardous). They are however still using that runway for takeoffs. This means, that until the work is finished, that only 27R can be used for landing. The approach to 27R is nearer to Brentford which is why we are all noticing the noise all day.Having read this all back, I've realised it's as long-winded as the original post - sorry, but I hope it helps to answer your question. Let's hope for a nice easterly breeze soon!
Paul Garnham ● 6831d