Aircraft noise measurements over London ‘inaccurate and misleading’
Date added: January 2, 2012
HACAN East, the new group representing residents affected by London City Airport, says that the way the government currently measure aircraft noise over much of London is both inaccurate and misleading. Now that aircraft approaching Heathrow join the approach path much further to the east than they used to, residents affected by planes using London City Airport are also overflown by planes descending to Heathrow. But the noise data for flights using each airport are measured separately and not combined. This problem has been known since 2007, and recognized as underestimating the total noise heard by residents. If the noise levels are combined, aircraft noise levels in parts of East London matches those in West London
Aircraft noise measurements ‘inaccurate and misleading’
HACAN East (1), the campaign group which represents residents under the flight paths of City and Heathrow airports in East and South East London, has described the way aircraft noise in the area is currently measured as ‘inaccurate and misleading’. The campaigners are calling on the Government to include proposals to change the system in its new aviation policy which is expected to come out for public consultation before the end of March.
At present the way the noise is measured doesn’t take account of the fact that tens of thousands of people in East and South East London live under both the City and Heathrow flight paths. When noise measurements are taken for flights from each of the airports, they are not combined. As far back as 2007, this was recognized as underestimating the total noise heard by residents. A report from the leading noise experts, Bureau Veritas, found that, if the noise levels were combined, aircraft noise levels in parts of East London matched those in West London (2).
John Stewart, the Chair of HACAN East, said, “Currently the way noise is measured underestimates the total noise suffered by people living under the flight paths of both London City and Heathrow airports. It paints an inaccurate and misleading picture. We will be lobbying the Government to ensure changes are made when it comes out with its proposals for its new aviation policy in the early part of this year.”
(1). HACAN East was formed last year. It is a sister organisation of the long-established HACAN, which represents residents under the Heathrow flight paths. You can find us on: http://hacaneast.org.uk/ Twitter: @hacaneast
(carried out a few years ago, but just as relevant today)
UK airports have traditionally used the Leq method of measuring noise. Noise is averaged out over a 16 hour day, and then over the year. Only when the annual average is over 57 decibels is noise considered to be a problem. Many consider that does not reflect reality. For example, in West London, places like Putney and Fulham, clearly affected by aircraft noise, are outside the 57 decibel contour. The EU required airports to use another method known as Lden when drawing up their Noise Action Plans. Lden averages out the noise over a 12 hour day; a 4 hour evening; and then an 8 hour night. It then adds 5 decibels to the evening figure and 10 decibels to the night figure to allow for lower general background noise levels. The EU says it more accurately reflects the way people hear noise. At Heathrow, the differences are startling. Around 250,000 people live within the 57 Leq contour; over 700,000 within the 55 Lden contour. An Lden contour for City Airport would almost include many more people.
No Place to Hide
(extracts) Key findings:
Aircraft noise has become a London-wide problem.
In places 20 kilometres from Heathrow “aircraft noise dominated the local environment.” For example, there was “an almost constant background of aircraft noise” in Kennington Park, close to the Oval Cricket Ground, well over 15 kilometres from the airport.
In some areas of East London flown over by both Heathrow planes and City Airport noise levels were comparable to those in parts of West London. Key conclusions:
“In terms of geographical spread, the greatest increases have occurred in the early morning and in the evening – arguably the relatively more sensitive times of day”
“The relatively high levels of aircraft noise that do occur at some distance from the airport are certainly enough to be noticed by those living in those areas and in certain circumstances to cause some disturbance and intrusion.”
“The results of this study do explain why aircraft noise from operations at London Heathrow is a cause for concern beyond the boundary of (the officially recognised*) contour.”
* The official contour (where the Government and aviation industry acknowledge there may be a noise problem) contains the area enclosed by the 57 dB(A) LAeq contour. That is, the area where aircraft noise averages out at 57 decibels over the course of the summer – roughly between Barnes and Heathrow. Key reason for the increase:
The growth in the number of aircraft using Heathrow (and in some areas, City Airport) has required changes to be made to landing patterns:
Many more routes between the holding stacks and the airport are now in use;
Planes are forced to take less direct routes from the stacks, resulting in many more turning movements (which has increased noise levels).
In Ruskin Park in South London, 20 kilometres from the airport, aircraft noise dominates the local environment. During busy hours a plane flies over almost every 90 seconds, usually louder than 60 decibels.
In Kennington Park, just slightly closer to the airport, planes are coming over every 97 seconds, almost all over 60 decibels and the vast majority heading for Heathrow.
At Clapham Common, well outside the area where noise is officially recognised as a problem, aircraft fly over at the rate of one a minute, the vast majority of them registering over 60 decibels.
In Poplar it recorded 84 planes flying over in a two hour period, 45 Heathrow and 26 City Airport
The noise level of the Heathrow aircraft ranged from 60 – 69 decibels and the City aircraft from 64 – 82 decibels.
Continuous Descent Approach
The study did not specifically look at Continuous Descent Approach (CDA), the procedure which aircraft are encouraged to use when landing at Heathrow. Aircraft use CDA to achieve a smoother approach to the airport, rather than the ‘step-by-step’ approach they once adopted.
There does seem to have been some correlation between the greater use of CDA and the increase in the number of complaints from areas more distant from the airport.
Is this because, in order to achieve a smoother landing, planes need to get in line further from Heathrow, thus causing the sort of constant background noise the study noted in places like Kennington Park?
Key implications for decision-makers:
The area where aircraft noise is a problem is much wider than that officially recognised by the authorities. Unless this is factored into policy-making processes, there is the danger of policy being formulated on the basis of poor information.
Consultation of any plans to expand Heathrow should include local authorities and residents well beyond West London. Indeed, there is a case for involving these local authorities to participate in regular consultation meetings such as the Heathrow Area Consultative Committee.
The noise contours for areas affected by planes from both Heathrow and City airports need to reflect the combined effect of the aircraft passing overhead.
Further work needs to be undertaken on whether the greater use of Continuous Descent Approach has worsened noise levels in areas further from the airport.
Heathrow aircraft are causing noise problems in east and south-east London because they’re joining their final approach path 2-3 miles further east than they used to
BAA, the owners of Heathrow, has recognized that planes using the airport cause noise problems beyond the traditional area of West London. In a ground-breaking report, produced jointly with HACAN, the sister body of HACAN East, BAA has acknowledged that parts of east and south east London have problems they did not have before: “statistical analysis has shown that the most common point by which aircraft join their final approach to Heathrow has moved around 2 – 3 miles further from the airport in the last 15 or so years.” Aircraft used to join their final approach to Heathrow around Barnes in West London. The fact that the joining point was moved further east has resulted in big noise problems for places in east and south east London. These problems have become even more noticeable s the number of planes using Heathrow has increased. The report, which British Airways and Air Traffic Control (NATS) have also signed up to, has been sent to the Department for Transport.
Newham Council officers denied that flights from City Airport caused any noise problems in the neighbouring boroughs of Waltham Forest and Redbridge when questioned at the recent London Assembly environment scrutiny committee (1st December).
“We despair at Newham Council’s continued refusal to admit the impact the airport is having on neighbouring boroughs.”
John East, representing the council, said they were “content noise was at acceptable levels.” John Stewart, the chair HACAN East, who was at the Assembly hearing, said, “We despair at Newham Council’s continued refusal to admit the impact the airport is having on neighbouring boroughs. Its officials are hiding behind outdated statistics to deny the reality of what is happening on the ground.”