The Airports Commission Report: Carbon Emissions, Air Quality and Noise Contents



62.Over the past 50 years aircraft have become less noisy. But during the same period air traffic has increased, so as the Airports Commission noted, people living close to airports continue to have significant concerns about the impact of aviation noise not only on their daily lives, but on their health and on their children’s education. The Commission said:

Aviation noise is therefore a central issue in assessing the impacts of any proposal for expansion. It is also important to consider the most effective approaches to mitigating or compensating for noise impacts, to ensure that they are managed and reduced wherever possible.88

The Commission’s noise assessment informed its recommended means of managing and reducing noise impact—in particular, its key recommendation of a Heathrow “noise envelope”: a restriction on the amount of noise produced at the airport after its expansion.89

Assessing People’s Experience of Aviation Noise

63.The Commission used several metrics to assess the noise impact on people of an expanded Heathrow. It established noise contours—areas around an airport in which certain average noise levels are experienced by people—for an expanded Heathrow, based on average noise experienced at 57dB90 and 54dB between 7am and 11pm; average noise experienced at 55dB over 24 hours; and single noise events exceeding 70dB between 7am and 11pm and 60dB between 11pm and 7am.91 Sir Howard and his team said they measured single noise events, as well as average noise experienced, because they recognised “it is not only the noise level which is important but also the number of flights that are experienced”.92

64.Residents near Heathrow and others who submitted evidence were keen to demonstrate that the average noise metric alone did not reflect their actual experience of noise. Richmond Heathrow Campaign referred to “the type of aircraft, aircraft height, take-off or landing engine power… location relative to the flight path, and time (day, evening or night),” and said, “These variations matter but are not fully reflected by average noise indicators.”93 Mr Paul McGuinness, a Teddington resident, noted that average noise contours were not designed to measure “the very thing that disturbs people, which is peak noise”.94 We also heard that average noise contours might not account for large numbers of people living in areas overflown infrequently but loudly. Stephen Clark, an infrastructure consultant, explained that Twickenham and other areas nearby were overflown only when the wind came from the east, about 30% of the time. But when they were, he said, they were “severely impacted for over 17 hours a day, with literally hundreds of flights, many generating 70-90 decibels.” He added, “By using averages these areas are excluded from the Commission’s Study Area.”95 Mr Clark also noted that Heathrow ltd. had itself commissioned more in-depth analysis, measuring average noise contours separately on easterly and westerly operations.96

65.The Commission acknowledged the problem with using only average noise experienced and said if single noise events were measured: “The layman may find it easier to relate to the thought that ‘within this area, I am likely to hear noise exceeding x limit more than 100 times a day’.” But the Commission also explained that these measures did not differentiate between the level of noise above a certain threshold, or the duration of noise events, so a 10-second event at 71dB(A) would count for the same as a 40-second event at 91dB(A).97 As HACAN has acknowledged, the Commission therefore recommended using a combination of measures.98

66.Government aviation noise policy was most recently articulated in 2013. The then-Government noted there was no firm consensus on the way to measure noise impacts and said, “We will keep our policy under review in the light of any new emerging evidence.” Their policy said average noise metrics were important for showing historical noise trends around airports, but encouraged airports to develop other measures, too, in consultation with local communities.99

67.The Commission highlighted the inadequacy of relying purely on averages when measuring the impact of noise on communities. People living close to Heathrow do not experience noise from flights into and out of the airport as a constant decibel level throughout the day or night. So, although the measurement of average noise experienced provides a helpful snapshot of noise over a short period, and a useful historical comparison, it does not reflect a range of variables such as the type, height or engine power of an aircraft. Nor does it account for peak noise events. And, if it lacks detail, it may also ignore a swathe of people who are overflown infrequently but loudly. The Government, when assessing the noise impact of an expanded Heathrow, should do so against a full range of metrics and not just average noise experienced. These metrics need to be measured against international standards such as World Health Organisation recommendations and inform a change in Government policy on aviation noise.

An Aviation Noise Survey

68.People were concerned to ensure not only that a range of metrics were used to measure people’s experience of noise, but that the average noise threshold constituting significant annoyance, of 57dBLAeq100, was reassessed.101

69.The Commission recommended that in the event of expansion, Heathrow be legally bound to operate within a noise envelope—a cap, or limit, on noise.102 It was criticised for not including any detail on this proposal,103 but it was the Government that was blamed—for failing to provide clearer noise guidance on which the Commission could base more comprehensive recommendations. The 2M group of London Boroughs said the Commission had been unable to go into detail because there was no policy framework in which to limit noise levels or numbers of flights.104 It therefore suggested that the Government commit to a “robust social survey” of aircraft noise which could then be used as the scientific basis for further noise mitigation strategies.105 Hounslow Council agreed, stating it wanted a “robust and independent social survey” before expansion was allowed.106 But it was not only those representing local people who wanted further work. The industry body Sustainable Aviation also called on the Government to support independent research to improve its understanding of people’s reaction to aircraft noise events, “to reduce the number of individuals annoyed by aircraft noise.”107

70.We heard that the last such survey was carried out over 30 years ago.108 The findings of the Aircraft Noise Index Study (ANIS), undertaken in 1982, are still reflected in the use of the 57dBLAeq threshold. A more recent exercise took place in 2007 but was not adopted as government policy.109 Commentators did not accept all findings of the Attitudes to Noise from Aviation Sources in England (ANASE, 2007), but its conclusion that more people are now annoyed by a given level of aircraft noise exposure than they were when ANIS was conducted was, according to the Commission, “generally accepted.” World Health Organisation (WHO) guidance, released in 1999, also identified a lower threshold than ANIS, 55dBLAeq, for the onset of serious annoyance during the day.110 The WHO was due to update its guidance in late 2015,111 while the DfT is also apparently undertaking a review of public sensitivity to aviation noise, the results of which may be available in 2016.112

71.Some witnesses suggested the WHO threshold should be adopted. Daniel Moylan of TfL told us that the 57dB limit “was recommended for tightening to 55 12 or 13 years ago… the Government refused to implement it because of the limiting effect it would have had on Heathrow’s operation.”113 The Aviation Environment Federation recommended its adoption, too, but thought that doing so with expansion was “very hard to envisage.”114 We were also reminded that different people might experience the same noise level in different ways. Lord True, representing the 2M group of councils, said, “the rest of us might be inured to 55 or 57, but there will be hundreds and thousands of people who have not experienced that before.”115

72.Sir Howard suggested that an Independent Aviation Noise authority, another Commission recommendation, could undertake this survey.116 HACAN thought it should be introduced regardless of whether and where new runways were built.117 If it did this piece of work, Sir Howard said, “you could start to get some clarity on a lot of the debates about which particular noise level, who it should be measured by, and what social attitudes would be.”118

73.The Commission recommended the establishment of an Independent Aviation Noise Authority. This body will need a more up to date understanding of people’s attitudes to noise if it is to be credible. One of the first tasks of such a body should be to undertake a survey of people’s attitudes to aviation noise. The results of this survey should underpin both its own work and future Government policy on managing noise. In particular, they should form part of a piece of work to develop a set of metrics to assess noise impact.

A Noise Benchmark

74.The Airports Commission concluded that with new, quieter aircraft and redesigned flight paths dispersing noise more widely, “It would be possible to ensure that noise from the airport… would not exceed current levels across a wide range of metrics, both during the day and at night.”119 Heathrow ltd. drew on this in its submission and, under the heading “Better than today”, stated: “The Airports Commission’s analysis shows that across all metrics, the noise impact of an expanded Heathrow will reduce compared to today.”120

75.TfL was, however, critical of the Commission’s statement that its proposed mitigations could ensure noise did not exceed current levels. TfL said this was contrary to the DfT’s Transport Appraisal Guidance (TAG) methodologies for noise assessments, which require a comparison between doing something and doing the minimum for the same future year.121 Steve Mitchell, a fellow of the Institute of Acoustics, expanded on TfL’s point, noting the Commission’s own Appraisal Framework stated that noise would be assessed in relation to the Commission’s “do-minimum” scenario.122

76.The 2M group of councils summed up the perceived problem with benchmarking noise against current levels, stating that a noise envelope that ensured fewer people were affected by noise than today was “not an acceptable objective for communities who require an improvement on the current unacceptable levels of noise.”123 We put this point to the Commission’s former Chair, Sir Howard Davies, who said:

On some noise measures, a new three runway airport would in fact be less irritating than an existing two runway airport, partly because of the different configuration of the flights. You could put them further to the north and overfly fewer people. You have the flights coming in at higher level, so some of the flights that are coming in low over central London in the morning would not be coming in low over central London in the morning, they would be coming in over less populated areas a bit further to the north and they would be higher.124

77.We received submissions voicing concerns about the assumptions the Commission had made in its noise modelling. For example, 2M said the National Air Traffic Control Service had already cautioned the Commission that assumed landing rates using new curved approaches might not be attainable in practice.125 But, based on the Commission’s modelling, we found that the question of whether a future three-runway airport could be less noisy than a future two-runway airport depended on which operational scenario, noise contour and year were assessed.

78.The Commission considered three future airport operational scenarios: one that minimised the total number of people affected by expansion; one that minimised the number of people newly affected; and one that maximised people’s respite from overflying. Irrespective of the scenario, the Commission’s figures showed that on the 57dBLAeq noise contour in 2030 there would be between 13,000 and 27,000 net newly affected people; in 2040, 23,500 and 42,000; and in 2050, 23,100 and 45,000.126 On the “maximise respite” scenario, at 54dB LAeq 16-hour contour in 2030 and 2040, however, three runways were shown to affect fewer people than two, while in 2050 three runways were shown to affect more people than two.127 On the 55dB Lden 24-hour metric and the maximise-respite scenario, an expanded Heathrow was shown to affect fewer people than a two-runway airport in 2030, 2040 and 2050, while on the other two scenarios results were less consistent.128


79.The evidence we received from residents showed that length and predictability of respite was something they valued highly.129 The future airport operational “maximise respite” scenario, in which people’s respite from overflying was prioritised, showed more consistently--based on the Commission’s modelling--that a future three-runway Heathrow could be less noisy than a future two-runway airport. Respite currently allows residents close to Heathrow to benefit from relief from overflying for about half the operating day, although these period are sometimes infringed. In future the Commission said:

A third runway would allow periods of predictable respite to be more reliably maintained, even if respite periods from runway alternation would be reduced with additional capacity.130

80.Under expansion the Commission said respite would reduce to one third of the operating day. TfL made two criticisms of this proposal. First, it said the promise of more predictable respite relied on the airport not being capacity constrained, and the Commission’s own findings suggested Heathrow would be “effectively full up” shortly after opening.131 Second, Daniel Moylan from TfL noted that:

For over half of the communities it [respite] will fall to only 25% of the day and for the others it will be 50%, so that the 30% is an average and includes 50% of the affected population.132

81.For residents around Heathrow, noise is a major part of their day to day lives. Understandably, they are deeply concerned about the impact of an expanded airport. The Government needs to demonstrate that, in assessing the case for expansion, it has based its decision on whether an expanded Heathrow would be noisier or less noisy than a two runway Heathrow at the same point in time - taking into account respite and the need for predicable relief from overflying.

Night Flights

82.When the Commission compared noise from an expanded Heathrow with that of current operations, it found that it could be less noisy than today during both the day and night. The Commission therefore also concluded that the extra capacity with expansion would allow for a ban on night flights at the airport between 11.30pm and 6am. The Commission’s detailed analysis, which found that in certain circumstances an expanded Heathrow could be less noisy than a future two-runway airport, also came to these conclusions having compared daytime and night time operations.

83.Local residents and councils were particularly keen to see night flights banned, given their perceived impact on health. Some residents proposed a longer period without flights. Evidence from the industry, however, was resistant to the idea of an absolute ban because of the impact on certain high value routes.133

84.The Commission’s recommended ban on night flights was a key part of the package proposed by the Commission. The Government should publish a plan, including a series of binding milestones, to deliver the proposed ban as part of any announcement to proceed with expansion at Heathrow as recommended by the Commission.


85.A lack of trust towards Heathrow was a theme in some of the submissions we received from residents’ groups.134 Hounslow Council told us it was “acutely aware that the promises made by Heathrow’s owners during the Terminal 5 inquiry and on other occasions [had] not been honoured,” although they also gave the new management credit for being “a lot more engaging”.135 When Sir Howard appeared before the London Assembly, he heard how Heathrow ltd. management had told local politicians, “Terminal 5 and that is it. We will never need anything again, ever.”136

86.One area this lack of trust manifested itself was the response to Heathrow ltd.’s offer to spend more than £1 billion in the local community, including £700 million on noise insulation. Richmond Heathrow Campaign noted that Heathrow ltd. had promised to refit 42 schools and community buildings in 2005. This work was completed earlier this year at a cost of £4.8 million. The Campaign questioned how long it would take to invest £700 million.137

87.The Commission recommended the establishment of an Independent Aviation Noise Authority to provide impartial expert advice and to help communities and airports to agree noise management strategies.138 Lack of trust was also one reason why it recommended a new Community Engagement Board, “with real influence over spending on compensation and community support and over the airport’s operations … set up under an independent chair.”139 Heathrow ltd. itself was supportive in principle of both the Commission’s recommended bodies but wanted the Government to define and consult on the detail of how they would work in practice.140

88.Levels of trust between Heathrow and the local community are an historical and enduring issue which has impaired effective community engagement. If the Government decides in favour of expansion it should put in place a framework to ensure that mitigating measures are introduced promptly. The Airports Commission also recommended the establishment of two bodies - an Independent Aviation Noise Authority and a Community Engagement Board - to address this. As part of the efforts to restore trust and effective community engagement, these should be introduced in the next year, even if the Government decides against Heathrow expansion. One of the first pieces of work for the Community Engagement Board should be to establish the extent to which commitments made at the time of Terminal 5 have been met.

88 Airports Commission, Airports Commission: Final Report, July 2015, pp169-170

89 Airports Commission, Airports Commission: Final Report, July 2015, p278

90 Decibel (dB)

91 Airports Commission, Airports Commission: Final Report, July 2015, p170

92 Airports Commission, Airports Commission: Final Report, July 2015, p170

93 Richmond Heathrow Campaign, ACR0066, Annex 3, 1(iii)

94 Mr Paul McGuinness, ACR0074

95 Stephen Clark, ACR0021

96 Stephen Clark, ACR0021. The Heathrow report referred to was, Westerly and Easterly Departure Trials 2014--Noise Analysis and Community Response, July 2015.

97 Airports Commission, Discussion Paper 05: Aviation Noise, July 2013, p23

98 HACAN, ACR0008, para 14; Airports Commission, Airports Commission: Final Report, July 2015, p278

99 HM Government, Aviation Policy Framework, Cm 8584, March 2013, p58

100 dBLAeq refers to “Equivalent continuous level” - in effect the average of an uneven pattern of noise over a set period of time.

101 In the most recent policy announcement on aviation noise, Ministers said they would continue to use 57dB LAeq as the onset of significant community annoyance. HM Government, Aviation Policy Framework, Cm 8584, March 2013, p58

102 Airports Commission, Airports Commission: Final Report, July 2015, p278. The Commission said the envelope could relate to the physical area of noise contours, using any or a combination of the noise metrics it had used; to the number of people within a noise contour or group of contours; or to a points-based system in which individual aircraft are rated by their noise impacts.

103 See, for example, Q63 [Daniel Moylan], [Lord True]

104 2M, ACR0056, para 2.7

105 2M, ACR0056, para 2.11

106 London Borough of Hounslow, ACR0059, para 2.18

107 Sustainable Aviation, ACR0073, para 4.3

108 Q63 [Lord True]; Stephen Clark, ACR0021

109 Q198 [Philip Graham]

110 Airports Commission, Discussion Paper 05: Noise, July 2013, pp33-34

111 Dr Charlotte Clark, Centre for Psychiatry, Barts & the London School of Medicine, Queen Mary University of London, Aircraft noise effects on health, Prepared for the Airports Commission, May 2015, p26

112 Stephen Clark, ACR0021

113 Q49; See also Heathrow Associates, ACR0072, para 10

114 Aviation Environment Federation, ACR0057, para 34

115 Qq63, 65

116 The Commission said an independent aviation authority could work with developers, operators and communities to, among other things, define a noise envelope and balance aviation growth and noise control; and provide statutory advice to the Secretary of State for Transport and Civil Aviation Authority in respect of the proper structure for noise compensation schemes. See Airports Commission, Airports Commission: Final Report, July 2015, p304

117 HACAN, ACR0008, para 16

118 Q198

119 Airports Commission, Airports Commission: Final Report, July 2015, p26

120 Heathrow Airport Limited, ACR0081, para 3.3.11

121 Transport for London, ACR0075, para 4.1. In Heathrow’s case, doing something means expansion, while doing the minimum means retention of a two-runway facility.

122 Steve Mitchell, ACR0071, paras 10,11

123 2M, ACR0056, para 3.8

124 Q201

125 2M, ACR0056, paras 2.10, 2.16

126 Civil Aviation Authority, Noise Modelling for the Airports Commission: Compendium of Results, June 2015, table c3

127 Civil Aviation Authority, Noise Modelling for the Airports Commission: Compendium of Results, June 2015, tables A27-A41

128 Civil Aviation Authority, Noise Modelling for the Airports Commission: Compendium of Results, June 2015, table c4

129 See for example Richmond Heathrow Campaign, ACR0066, Annex 3, (1)(b)(iv)

130 Airports Commission, Airports Commission: Final Report, July 2015, p31

131 Transport for London, ACR0075, para 4.5

132 Q67

133 See for example, ABTA, ACR0026, para 8

134 See for example Mr Paul McGuinness, ACR0074 ; Mr Steve Mitchell, ACR0071,; and Maureen Williams, ACR0070

135 London Borough of Hounslow, ACR0059, para 1.7; Oral Evidence, Cllr. Armit Mann, Q66

136 London Assembly, Plenary Meeting , 8 September 2015

137 Richmond Heathrow Campaign, ACR0066, Annex 3, (1)(b)(vi)

138 Airports Commission, Airports Commission: Final Report, para 14.16

139 Airports Commission, Airports Commission: Final Report, p 32

140 Heathrow Airport Limited, ACR0081, executive summary

© Parliamentary copyright 2015

Prepared 30 November 2015