Improving operations
Improving the way airports and aircraft operate
Reducing noise isn’t just about technical improvements and meeting Government regulations. The airports, airlines and Air Traffic Control are doing lots to reduce the noise by changing how the planes actually operate.
Continuous Descent Approach
In the past, when Air Traffic Control was directing a plane in to land, it was more common for the pilot to drop the plane’s height and then level out for a few miles, before dropping height and levelling out again. This way, the plane landed as if it was coming down a flight of very steep stairs.
The problem with this is that it creates unnecessary noise, because for each level step, the pilots need to increase the power to the planes engines and they are lower at times than they need to be.
Please note the diagram below provides example approach profiles and should not be considered as indicative of all CDA or non CDA profiles. For further information on the complexities of CDA please contact BAA
To address this, BAA chaired an industry-wide group to produce a ‘Code of Best Practice for Arrivals Noise’ and developed technology to enable easy and accurate measurement of ‘Continuous Descent Approach’, often shortened to ‘CDA’.
Under this procedure, pilots descend on a continuous, smooth glide path – like standing on an escalator rather than walking down the deep stairs. Pilots now don’t have to vary the amount of power going into the engines – it’s constant – and they stay higher over the ground than under this type of approach, as the graphic below illustrates.
In 2004, over 80% of all Heathrow’s arriving planes used CDA (this rose to 92% between 11.30pm and 6am). We are constantly working with airlines to get all pilots to use it.
Financial incentives – the carrot and stick
Every airport charges the airlines to use its facilities. At BAA’s airports, the level of the charge per plane is regulated by the Civil Aviation Authority.
To get the noise levels down, we have worked out a discount scheme for airlines that use the quietest aircraft, so that they have an incentive to use quieter planes. But if an airline uses noisy planes, we’ll actually charge them more to use the airport.
This scheme means that the noisiest planes can end up paying three times the normal landing charge, and many pay one and a half times the charge. On the other hand, the airlines with the quietest planes pay less than the normal charge – just 90%.
Even though our landing charges are competitive, the scheme is an encouragement for airlines to use their quietest fleet.
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