People who are new to Reading may well have noticed just how many aeroplane fly over the campus. We seem to get one a minute at times. In the last few days it has been especially busy and I thought I would give some explanation why.
Heathrow is only about 20 miles away to our east and if you look at the map, you will see that the two main runways run east-west. Aeroplanes like to land and take off into the wind, so when the wind is coming from the east, the planes land from the west of the airport. On approach, they line up with the runway and use Instrumented Landing System (ILS) to guide them in. In fact, we are almost in direct line of the runways but it is the north runway which aeroplanes will land on if they are coming in from the west (this is due to the Cranford Agreement that prevents this runway being used for take offs). This lies on a line that passes a few miles north of campus, approx. over the village of Sonning.
To make things even busier, incoming planes are often 'stacked' prior to arrival. There are four stacks around the airport, about 20 miles out at 10, 2 4 and 8 oclock. When it is their turn, air traffic control put the planes onto final approach where they must leave the stacks and then line up with the ILS. This is why you often see aeroplanes coming in first from the north and then from the south, banking hard to take a west to east line about 2-3 miles north of campus.
Over the past few days, the wind has been from the east. You can check for yourself the wind direction of Heathrow at http://weather.noaa.gov/weather/current/EGLL.html. Yesterday was quieter (although I doubt it was noticable due to the rain) as the wind was from the west - which is the prevailing direction. There is a preference for landing east-west as this abates takeoff noise over central London so westerly approaches only occur when the e-w vector exceeds 5kn.
Keywords: aeroplanes, heathrow