Aviation Noise

What is Aviation Noise?

Aviation noise is unwanted sound generated by aircraft, and it is a serious and growing problem in the UK. As airports expand and air services increase, more and more homes are exposed for large parts of the day to a persistent background noise from aircraft.

Noise from aircraft is subject to an entirely different regulatory regime to other noise pollution. The Civil Aviation Act 1982 provides that no action for trespass or nuisance can be taken as long as an aircraft observes the rules of the Air and Air Traffic Control Regulations, which also cover ground movements.

The UK's main measure of aviation noise is Equivalent Continuous Sound Level (Leq dBa). This averages the sound energy monitored from all aircraft noise events in a certain area over a 16 hour period each day (0700 and 2300). Low Community Annoyance is registered at 57 Leq, Medium Annoyance at 63 Leq and High Annoyance at 69 Leq.

Background

The Air Navigation Act 1920 provided the basis of the UK's aviation noise regulation regime, by exempting aviation from nuisance sanctions, in order to stimulate the nascent industry.

This principle was reaffirmed in the Civil Aviation Act 1982, which nonetheless set out a number of provisions for controlling noise at larger airports through a process of "designation", which has only been applied to date to Heathrow, Gatwick and Stansted. By their Section 78 designation, the Transport Secretary is responsible for regulating take-off and landing noise at these airports.

In practice, noise restrictions at designated airports have been implemented through restrictions on departing aircraft noise, controls on night flying and (at Heathrow and Gatwick, under Section 79) housing noise insulation schemes.

At other airports, the successive governments have continued to favour local resolution. Councils' main instrument in this regard is the Section 106 Obligation, a condition that can be placed on planning permission. These Obligations can limit movement numbers, operating hours and the types of permitted aircraft. Voluntary agreements can also be reached. London City Airport and Luton Airport, for example, have agreed maximum noise exposure contours, which must not be exceeded.

Aviation is necessarily an international business, making unilateral domestic regulation difficult. However, successive agreements of the International Civil Aviation Organisation (ICAO) have sought to impose controls on aircraft design in order to minimise noise pollution.

Since the 1960s, jet engines have become four times quieter. A process of driving up noise pollution standards has been pursued by the ICAO, and by the European Civil Aviation Conference. In 2002, "Chapter 2" aircraft were outlawed from the EU, and the new "Chapter 4" comes into force in January 2006, which improves upon the current "Chapter 3" standard by a cumulative 10 dBa. The majority of aircraft in service today already meet the Chapter 4 requirements. EU regulation of aviation noise has focused on improving engine technology to date.

In 2001, the ICAO Assembly agreed that a balance of at-source restrictions, planning controls, operating restrictions and noise abatement practices by pilots and air traffic controllers would form the appropriate methods to address aviation noise.

Night flights are a particularly controversial aspect of aviation noise. Studies have shown that sleep can be disturbed at a relatively low Leq level of just 30. The first restrictions on night flights were imposed at Heathrow in 1962. Reviews have taken place since then in 1988, 1993 and 1998. Ten airports are now subject to night noise controls under the Aerodromes (Noise Restrictions) (Rules and Procedures) Regulations 2003. The Government undertook to consult on a new night noise regime in 2004, and decided that the existing limits on night flights should remain until 2012.

A contributing factor to this decision was the widespread media publicity in 2001 following legal action by a group of residents known collectively as the Heathrow Association for the Control of Aircraft Noise (Hacan). They took their case to the European Court of Human Rights, which endorsed the Government's right to balance the economic interests of airlines in providing night flights against the welfare of local people. The Government agreed to review arrangements in the wake of the case.

The 2003 White Paper, which led to the Civil Aviation Bill, outlined the measures required to tackle the noise problem, highlighting in particular: the need to promote low noise engine and airframe research and technology; complete integration of the International Civil Aviation Organisation guidelines on noise control; implement EU directive 2002/49/EC regarding noise mapping; widen the use of economic instruments such as differential landing charges and amend and strengthen existing domestic legislation.

Military aircraft present a different sort of problem, insofar as they are exempted from all controls under Crown Immunity. While the armed forces carry out high levels of low flying exercises in some parts of the country, the MoD has offered assurances that it will only invoke its immunity to protect "operational effectiveness".

Controversies

Many aspects of the UK's aviation noise control regime are highly controversial, as demonstrated by the Hacan case.

The World Health Organisation argues that noise pollution can cause interference with communication, sleep disturbance, increased annoyance responses, noise-induced hearing loss, learning acquisition, performance effects, and cardiovascular and physcophysiological effects. Studies have suggested that the reading age of children in schools under flight paths is below the national average.

However, this and the environmental problems associated with aviation are frequently outweighed in the eyes of government by the economic imperatives pressing for expansion of the sector. Indeed, this very expansion undermines many of the restrictions in place: Chapter 3 regulations permit greater levels of noise from larger aircraft; while the simple fact of greater numbers of aircraft movements push the Leq level upwards.

The Leq standard is also controversial. Firstly, it is not internationally recognised, with many other countries using different measures. Secondly, it is unresponsive to the number of noise events - a doubling of the number of same-level events in a given period would only increase the Leq by 3. Unlike other European indices, Leq does not give special weighting to night and other sensitive times of day. Opponents also argue that the Community Annoyance Thresholds, designed in the 1980s, are out of date. It is also argued that "Annoyance" is an inappropriate term to describe a phenomenon with the associated health risks of aviation noise.

The aviation industry is frequently accused of insensitivity to the problems of aircraft noise. While the majority of aircraft in service today are capable of meeting Chapter 4 requirements, industry resistance has kept the 30-year-old Chapter 3 standard in force. Moreover, in 2003, the Transport Select Committee heard from the chief technologist at Rolls Royce plc, a Professor Cumpsty, that best industry practice could exceed the Chapter 4 requirements by a further 14 dBa. Nonetheless, he also told the Committee that noise restrictions at Heathrow were driving the technology forward.

The proposed Heathrow expansion has reignited the issue of aviation noise, as the extended runways would have a flight path encompassing many areas that had previously been exempt from direct over-flights, including Chelsea and Notting Hill. If the expansion goes ahead as planned, the number of people subject to aviation noise levels above 57 decibels will rise from 375,000 to 535,000.


Statistics

At Heathrow, the number of air transport movements increased from 368,400 in 1990 to 430,706 in 1997. Over the same period at Gatwick they grew from 189,400 to 229,665 and at Stansted from 24,300 to 84,333

The number of people exposed to aircraft noise levels in excess of the Community Annoyance Threshold level fell from around 2 million in the 1970s to under 0.5 million in 2003

Statistics 1: (Source: Department for Transport, 2003); Statistic 2: (Source: "Aviation and the Environment", Report 195, Parliamentary Office of Science and Technology, 2003)

Quotes

“No action shall lie in respect of trespass or in respect of nuisance, by reason only of the flight of an aircraft over any property at a height above the ground which, having regard to wind, weather and all the circumstances of the case, is reasonable, or the ordinary incidents of such flight, so long as the provisions of any Air Navigation Order ... have been duly complied with”

Civil Aviation Act 1982, Section 76 (1)

“Our basic aim is to limit and, where possible, reduce the number of people in the UK significantly affected by aircraft noise.”

Department for Transport, “The Future of Air Transport”, 2003

“The Court does not find that, in substance, the authorities overstepped their margin of appreciation by failing to strike a fair balance between the right of the individuals affected by those regulations to respect for their private life and home, and the conflicting interests of others and of the community as a whole, nor does it find that there have been fundamental procedural flaws in the preparation of the 1993 regulations on limitations for night flights”

European Court of Human Rights Judgement, Hatton and Others vs UK, 2003