Community Noise Information Reports covering Twickenham and Teddington

This commentary sets out TAG’s views on the findings of the studies undertaken by Anderson Acoustics for Heathrow Airport based on noise monitoring and modelling at Strawberry Hill House (SHH) and the National Physical Laboratory (NPL). The paper is intended to be read in conjunction with the reports which can be found here:

  1. Community Noise Information Report Strawberry Hill House

Whilst the Community Noise Information Reports describe local conditions experienced over large areas of Twickenham and Teddington, the findings are also relevant to wider parts of south west London affected by south-easterly departures, including adjoining communities such as Fulwell, Ham, Hampton, Whitton, Feltham, Richmond Park, Molesey and beyond.The reports describe the changes that have occurred over the five-year period between 2011/12 and 2015/16 which have resulted in a very large rise in complaints about Heathrow’s operations. TAG believes there are issues raised by the analysis and that these require further investigation and action.

Crucially, Anderson’s analysis specifically addresses those impacts experienced when the area is actually overflown by departures, reported to be around one third of the time. There is a clear distinction between this approach and that followed by the DfT and CAA, who for many years have relied on metrics based on annual or summer season averages. These actually obscure the real impact of aviation on local communities and have led to a great understatement by the Government of the numbers of people significantly affected by aircraft noise.


Until 2014, when PBN trials were undertaken (resulting in massive protests and early termination of the trials), Teddington had never been associated with significant aircraft noise. In fact, Teddington was a place where people from Barnes, Sheen and Richmond and other areas under the arrivals flight paths came to live to escape aviation noise. Very few people were aware of the Noise Preferential Routes (NPRs) that crossed the area – there was no need to be. Up until 2014, residents were prepared to accept occasional and relatively minor disturbance from Heathrow departures, recognising the convenience and economic benefits of the airport.

Teddington’s peaceful reputation was reflected in the fact that the area had never fallen within the noise contour maps and residents were not even aware of the existence of the CAA’s local noise reports. Under the direction of the DfT and CAA the area was excluded from the Airports Commission’s Study Area and is not shown as impacted by aviation noise in any of the expansion scenarios anticipated in the Commission’s acoustic analysis.

The data presented in the reports confirms TAG’s view that conditions have deteriorated significantly over recent years. When the airport is on easterly operations noise levels are far in excess of WHO guidelines and of the thresholds for community annoyance and health impacts identified in the NORAH study, independent research undertaken very recently in Germany. This is most important as, increasingly, medical research is making clear the serious impacts on physical and mental health, sleep patterns and child development of excessive noise in communities.

TAG would highlight that the significant changes demonstrated by the data in the community noise reports have occurred without any prior notification, consultation or consent. The fact that this has been allowed to happen demonstrates the need for a fundamental reform of aviation governance in the UK. Residential communities are afforded no effective protection under the current aviation framework.

Strawberry Hill House Findings

The SHH report confirms that very significant changes occurred over this area (primarily affected by the DET NPR route) during an August to March monitoring period between 2011/12 and 2015/16. These include;

  • a 47% increase in the number of flights overall – caused by a combination of;
  • a 22% increase in the number of flights using the DET route when the airport is on easterly operations and
  • a 29% increase in the number of days when the airport flew on easterly operations
  • lower departures profiles, with particular problems caused by the largest and loudest planes
  • increased use of A380s which are the loudest planes passing over the area (contrary to the assumptions of the Airports Commission, not all new generation planes are quieter)
  • much higher concentration
  • the most extreme levels of noise being caused at the most anti-social times, especially late in the evening, which is particularly disruptive to sleeping patterns.

The combined effect of these changes (which TAG believes mainly to have occurred primarily around 2014and further investigation should be carried out to confirm this) is a radical change in the noise environment when the airport is on easterly operations. This is one of the main factors leading to a massive rise in the rate of complaints received by Heathrow.

The 22% increase in usage of the DET NPR is echoed by a 24% increase along the CPT NPR, although this route lies outside the TAG area and suffers less overflight in terms of absolute numbers. The increase in flights over Strawberry Hill on a typically easterly day is largely a result of reducing departures along routes leaving to the NE of the airport (see Page 13 of the report).

In the 2015/16 period, the proportion of all easterly departures using the DET route increased from 23% over the same period in 2011/12 to 28%.

Given the extreme conditions (that are caused by the combination of factors bullet-pointed above) along DET when the airport is on easterly operations (including the fact that the area receives no respite from continuous departures between 6 am and after 11 pm, i.e. more than17 hours a day), any increase in the number of days when the airport is on easterly operations is of the greatest concern to the community living in Teddington and west Twickenham. The long-term average of easterly operations is reported by the CAA to be 23% during the ‘summer period’ (the only period apparently considered by the CAA); however, during the monitoring period the average rate of easterly departures increased to 31% and this is not explained by linkage to exceptional weather conditions (Page 12).

TAG’s interpretation of the data in the reports suggests there may well have been a different approach between 2011/12 and 2015/16 towards easterly operation and prevailing wind conditions, and these concerns have been reinforced by recent experience. The protection of densely-populated residential communities to the east of the airport (under the western preference protocol), is especially important given the intensive levels of noise caused by departures and a complete lack of respite during easterly operations. Given the report’s findings showing a 29% increase in easterly operations during the monitoring period between 2011/12 and 2015/16 (Page 12), as well as more recent experience, TAG believes this should be investigated further. In addition, there should be greater transparency in relation to provision of wind data to the public and its impact on the direction of Heathrow’s operations.

Low departure profiles have been highlighted by TAG as a particular problem and research by Heathrow has confirmed it operates under regulatory requirements (set by the DfT) which are the least demanding of any comparable airport in the world (notwithstanding Heathrow affects the greatest number of people impacted by aviation noise in Europe).

The SHH report also shows how concentration along the DET NPR has increased significantly between 2011/12 and 2015/6 (Page 14). However, TAG considers that the extent of the concentration is not immediately apparent from the graphic analysis. Whilst the report shows both flight numbers and concentration differences over time through the SHH gate, if this analysis were combined into one chart it would show the full extent of the combined increases (TAG proposes that a graph should be produced on this basis). This is a most important consideration to people who are living under flight paths and who are now exposed to a great number of concentrated flights passing over at low altitude.

The NPL area has also suffered from increased concentration, lower departure profiles and more easterly days. However, the NPL gate experiences significantly fewer numbers of flights in absolute terms, and reflecting this the report applies different scales to the ‘heat map’ pictorial representation.Whilst SHH did not fall directly under the routes trialled for PBN it is believed that many of the changes identified in this report were introduced around the time of the 2014 trials and that conditions never returned to their previous state (see histogram on Page 12). TAG proposes this should be investigated further.Both SHH and NPL reports include a detailed hourly analysis of noise conditions across the day, highlighting when the most significant problems occur (see Pages 17 and 27).
This demonstrates that the most extreme conditions are experienced at the time of the day when they cause the most disruption and distress, i.e. between 10.00 pm and 11.00 pm. During this period at SHH the one-hour LAeq is 62 dB (Page 31). However, this only partially indicates the level of the problem, as the background noise (LA90) at this time of day is only 40 dB, a differential of 20 dB LAeq. As these figures are based on logarithmic scales the impact on peoples’ lives at these most antisocial times is seismic.
This is reinforced by flight frequency analysis which shows that at SHH there are on average 19 flights an hour (one every three minutes) between 10 pm and 11 pm (Page 28), with 18 of these generating more than 65 dB LAmax and 13 exceeding 70 dB LAmax (large long haul planes causing the majority of this disturbance) (Page 27). The noise levels generated by departing aircraft at this location should be considered in the context of WHO advice; moderate annoyance daytime and evening at 50 dBLAeq; serious annoyance at 55 dB LAeq; sleep disruption at an external average noise level of 45 dB LAeq and individual events of 45 dB LAmax. As a result, it is impossible when the airport is on easterly operations for people – particularly children – to get a full night’s sleep (in line with medical advice), especially given that the DfT defines the night period as being just 6.5 hours.

The report compares noise levels from different plane types and confirms the A380 to be the loudest (Page 25). Anderson provides clear advice that only overhead flights (within a 60-degree cone) should be used for comparing noise levels generated by different types of plane (Pages 9 and 22). Evidently it is not appropriate to compare noise levels generated by aircraft passing overhead with those travelling a kilometre or more away (this consideration is reinforced in the NPL report’s analysis which states that insufficient data exists in relation to A380s in this location to enable it to be compared to other aircraft).

Notwithstanding the very significant changes that occurred between 2011/12 and 2015/16 (total traffic up 47%; usage or route increased 22%) the report reaches a very surprising conclusion that, based on modelling on easterly summer days, average noise levels (LAeq16) have risen by only 1 dB across the day, notwithstanding an average noise level per flight of 70.5 dB LAmax (Page 35). TAG believes that, in the light of these findings, an averaging basis of analysis has very little utility indeed. This is considered in more detail in the later section of this commentary dealing with metrics.

National Physical Laboratory Findings

This area has also been impacted by very significant changes, although not to the same extent as SHH; on easterly operations it is overflown on a daily basis 136 times, compared to 213 in the case of SHH (Page 12). In addition, the average LAmax of each flight at NPL is 67.4 dBA, compared to 70.5 dBA at SHH. In summary, it receives fewer flights and on average they are quieter (Page 22).However, according to the report, compared to 2011/12, in the 2015/16 monitoring period the NPL area experienced 20% more departures (Page 3) (a function of a 29% increase in easterly operations but this gate taking a lower proportion of departures when the airport is on easterly operations). As noted in connection with SHH the correct application of westerly preference is of vital importance to the communities around the NPL since high levels of aviation noise are experienced without respite for circa 18 hours a day. 

In addition, as with SHH, this area has experienced significantly increased concentration (Page 14), lower departure profiles (Page 15), and is also badly affected by late departures on a regular basis. These factors are particularly damaging to the residents living under the MID and GAS NPRs.

Most importantly it also needs to be stressed that the whole of the Twickenham and Teddington area is affected by noise spreading across from one NPR route into another. Residents living in west Twickenham, north Teddington and Fulwell are affected by all the changes that have occurred at the SHH and NPL gates. Like SHH, the NPL area suffers the most extreme noise conditions late in the evening.

Page 27 shows 9 pm and 10 pm as the noisiest hours, but Page 17 indicates that this does not correspond to the number of departures through the NPL gate. This is likely to be due to two factors; the first being that the noisiest aircraft are used late in the evening; and secondly, that noise events at SHH (and possibly along CPT) are causing significant disturbance at the NPL. This is a key consideration as it indicates that the spread of noise impacts across a wide area of Teddington, Twickenham and Hampton.In terms of the comparative analysis of different planes, the A380 is not included as it does not pass directly overhead at the NPL.The conclusions drawn in the NPL report raise particular questions concerning metrics. Based on modelling, the report states that for easterly days there was less than 1 dB LAeq difference in average modelled daytime noise between 2011 and 2015 (Page 35).

However, Anderson notes that a 25% change in the number of noise events would correspond to a just 1 dB (circa) change in LAeq 16hr (Page 35). Having regard to the fact that the average total number of daily flights over NPL actually decreased between 2011 and 2015, the implication must be that, on average, planes are getting louder, that they are being flown in a way that causes them to cause more noise on the ground, or a very considerable amount of noise is spilling over from the DET route (which is being used more intensively).

Noise metrics

Appropriate bases of measurement and thresholds – underpinned by fully independent health impact and social attitude research – are the key to understanding aviation’s impact on residential communities. 

The reports recognise, correctly in TAG’s view, ‘the response to aircraft noise is related to more than average noise levels alone. The number of events and their individual levels are becoming increasingly recognised as a useful indicator of community response to aircraft noise.’The analysis contained in the SHH and NPL reports illustrates this point perfectly.

TAG would go further and say that annual average metrics are meaningless when an area can be subject to extreme levels of noise for 18 hours a day, sometimes for three week unbroken periods, making normal patterns of life impossible, and still be excluded from the Airports Commission Study Area.In order to set a context for understanding metrics the following key indicators have been extracted from the SHH and NPL reports.




Flights per easterly day (2011 figures in brackets)

213 (175) – Page 12

136 (142) – Page 12

Average noise per flight 2015 dB LAmax

70.5 (measured) – Page 22

67.4 (measured) – Page 22

Daily average 2015 Laeq 16hr (2011 average in brackets)

59 measured – Page 31 (58 as modelled – Page 35)

55 measured – Page 31 (52 as modelled – Page 35)

Worst hour 2015 Laeq 1hr; Overflight worst hour

62 dBA measured;
19 times – Pages 31 and 27

57 dBA measured;
9 times – Pages 31 and 27

N65 day 2015 (2011 in brackets)

Over 200 measured (175 as modelled)

85 measured (78 as modelled)

Looking across the columns it can be seen that during the monitoring period more than 200 noise events over 65 dB LAmax occurred daily at SHH compared to 85 at NPL (at average measured noise levels of 70.5 and 67.4 dB respectively). However, this translates into a seemingly small difference of 4 dBA on a LAeq 16hr basis. Likewise, an increase of 38 (22%) flights over SHH creates approximately only 1 dBA difference from its modelled average daily contour. Furthermore, whilst the actual number of flights over NPL has gone down (from 142 to 136 – Page 12) this actually leads to a modelled increase in noise events N65 over 5 years (from 78 to 85 – notwithstanding the total number of overflights being fewer – Page 35). The previous page sets out the possible causes.

It is clear from the above that average metrics based on LAeq, used by the DfT and the CAA, do little to reveal the experience of communities. There also seem to be significant differences between measured and annual modelled noise levels which need careful explanation to the lay reader. In TAG’s opinion, a system based on numbers of events measured against WHO-advised thresholds across a day, with an hourly breakdown (to highlight concentrations and the worst/most sensitive periods) will give a much better and clearer indication of levels of disruption to communities.


The data in the SHH and NPL Community Noise Reports confirm that Teddington, Twickenham, Hampton and adjoining areas (under the DET, MID, GAS and CPT NPRs) are affected very significantly when Heathrow is on easterly operations.Since 2011/12 there has been a marked deterioration of conditions, with a 22% intensification of use of the DET route. In addition, in comparison to the 2011/12 monitoring period, and affecting both SHH and NPL gates, the area suffered from 29% additional easterly operations from the airport.

Given that on easterly days the area experiences ongoing overflight resulting in extreme noise levels for approximately 18 hours a day, TAG considers it essential that westerly preference is correctly observed (the long-term summer season average for this operation is reported by the CAA as 23%).Whilst conditions at SHH are shown to be more extreme than NPL, much of the Teddington area is in fact affected by all three flight paths. Each flight path has also been subject to considerably lower departure profiles and much greater concentration than five years ago. It is suspected that the greatest changes occurred around the time of the PBN trials in 2014. Conditions have never reverted to their previous state.

All the above has occurred without notification, consultation or consent; this demonstrates perfectly the lack of protection for residential communities under the current aviation governance framework. In fact, no single organisation within the aviation industry has accepted responsibility for the changes identified in the reports.The serious deficiencies in the annual average approach to metrics are exposed by the reports. Very substantial changes have happened to the local noise environment yet the impact on LAeq is minimal. The changes though are very real to those who experience them, for example with flights passing over Strawberry Hill every three minutes between 10 pm and 11 pm at LAmax levels up to 80 dB or more – way beyond WHO- recommended levels to prevent sleep disturbance. Noise impacts from aviation should be assessed primarily by number of events and their noise level.

Although these conditions only occur for a proportion of the time, these periods are significant and can last for three weeks or more. The impact on sleeping patterns, mental health, education and child development during these times should be taken extremely seriously by Government, as they have an as yet unknown economic and human cost.

Action that should be taken in the light of the reports

Anderson’s reports are welcomed by TAG as they provide clear evidence of the significant deterioration in the noise environment that our area has seen over the past 2-3 years. However, there is little value in producing such reports if they do not result in clear plans and timescales to return current conditions to, as a minimum, pre-2014 trials levels. This is critical to improving community relations and the airport demonstrating that it takes seriously its promises to be a better neighbour.

Any subsequent proposed changes to airport operations that may result in changes to pre-2014 baseline noise levels should not be introduced by stealth but instead, with the proper consultation, with the onus on the aviation industry to demonstrate that these will not result in increased noise for any community.

Immediate steps that should be taken include the following priorities;

  • By the end of 2017, to revert noise conditions to their pre-2014 trial levels.
  • Heathrow currently has the lowest take-off rates of any country in the world, which is totally unacceptable given that this airport accounts for approximately 30% of all aviation noise pollution across Europe. New requirements to be set by the DfT for Heathrow should mandate: (1) all aircraft must attain at least 2,500’ (an increase from the current minimum of 1,000’) by 6.5km from start of roll (2) thereafter, all aircraft must keep climbing at a rate of at least 12% (up from 4%) until 6,000’ (up from 4,000’).
  • Specific restrictions should be set for the early morning and late evening periods in terms of the numbers of flights and the maximum level of noise these can generate, having regard to WHO advice.
  • Flight paths should be dispersed as far as possible, to create as far as possible a fair and equitable distribution of noise across all easterly NPRs. Intensification of use of the DET, GAS and MID NPRs should be reversed to the long-term distribution pattern.
  • Application of westerly preference over the past two years should be investigated, with prevailing wind conditions used to determine Heathrow’s operations made public in real-time, and monitored independently.

21st February 2017

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One Comment

  1. Jennie
    2nd October 2017

    I have 2 comments / questions. 1) Aren’t Andersen Acoustics a supplier to Heathrow for a number of reports, noise monitors etc. Shouldnt such investigational research be conducted via a neutral third party rather than a supplier who knows which side it’s bread is buttered? 2) I am pretty sure I remember reading that in the past, distance off the centre line of an NPR could not be measured accurately due to the technology used, and so the flights were plotted down the centre line of the route even those this didn’t necessarily reflect their actual position. I think this point is worth investigating for the 2011/12 data. I strongly suspect that this is why concentration doesn’t appear to have changed massively over time, despite us knowing that it has actually changed beyond recognition. Thanks for the great work you do on behalf of our community. J

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