Aircraft perform best if they can land and take off into the wind. A good breeze gives them extra lift for take off enabling them to gain height more quickly, which reduces further noise from the airport.
For about 75% of an average year, the wind blows from the west and southwest. This explains why aircraft mainly land over Barnes, Kew, Richmond, and Sheen and then take-off the other way, over Windsor.
However, when the wind is over 5 knots speed from the east (for the other 25% of the year), the aircraft need to take off to the east. The aircraft noise then mainly affects Twickenham, Teddington, Whitton and Hampton.
On days when the wind keeps changing direction, there is a time lag in changing the routes, due to the number of aircraft already lined up to land.
When there is less than 5 knots of wind or no wind at all, it makes no operational difference as to which way the aircraft take off. However, Air Traffic Control work to a rule known as ‘Westerly Preference’, which means that even though the wind can be up to 5 knots from the East, the aircraft still take off to the West. There is a debate as to whether or not this preference should be maintained. Despite these rules, the final decision lies in the hands of Air Traffic Control.
Occasionally the speed or gusting of cross winds causes turbulence around the hangars and the runway has to be switched so as to allow the pilots to maintain control of their aircraft.
Departing aircraft should take off following one of several Noise Preferential Routes (NPRs), which are designed to go over the areas of least population, such as Richmond and Bushy Parks. They should follow standard climb procedure to minimise noise, climbing steeply to 1500 feet and then at a set rate of climb. They are only allowed to leave the designated route when they are above 4000 feet, which is often outside our borough.
TEAM is the procedure where aircraft are allowed to land to both runways, with the aircraft in a staggered formation (for example, not directly side-by-side). This is done when severe inbound congestion occurs, or is expected to occur, involving airborne holding delays of 30 minutes or more, with at least 20 minutes delay in the inner stacks. As both runways are in use there is no alternation.
TEAM is already operational from 6 to 7am in the morning, and it seems is being increasingly used during the day, in order to clear congestion in the holding stacks. This is a worry as it means that the flight paths are getting too busy and it means that we lose the benefits of alternation for a period.
‘Mixed mode’ would mean arrivals and departures would operate to both runways simultaneously. ‘Mixed mode’ would mean the end of alternation. We support the view of our residents that alternation is better and will resist any proposed introduction of 'Mixed mode'.
Updated: 22 June 2017