Designing airframes and engines to reduce the noise

Improving operations

The UK's airports, airlines and ATC are doing lots to reduce the noise by changing how the planes are operated.

Continuous descent approach

In the past, when ATC was directing an aircraft plane in to land it was more common to drop 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 deep stairs.

However, this approach creates unnecessary noise, because to get down the ‘stairs’, pilots need to increase the power from their engines and that causes noise surges. To address this, an industry-wide group has produced a code of best practice for arrivals noise and developed technology to enable easy and accurate measurement of a continuous descent approach (CDA).

Under this procedure, pilots descend on a continuous, smooth glide path – like standing on an escalator rather than walking down deep stairs. Pilots don’t have to vary the amount of power going into the engines – it’s constant – and they stay higher over the ground than during a step-approach.

Over 80% of Gatwick arrivals use CDA – this rises to about 90% at night. We are constantly working with airlines to get all pilots to use it.

Financial incentives – the carrot and stick

Every airport charges airlines to use its facilities, with the level of the charge per plane regulated by the CAA.

To reduce noise levels further, 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, while 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 encourages airlines to use their quietest fleet.