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More stringent noise limits for aircraft departing from Heathrow, Gatwick and Stansted and a significant improvemen...
More stringent noise limits for aircraft departing from Heathrow, Gatwick and Stansted and a significant improvement in monitoring efficiency have been announced by the department of transport.

The noise limits for aircraft taking off from the three airports will be reduced by 3 dBA by day (7am-11pm) and 2 dBA by night (11pm-7am) to 94 dBA and 87 dBA respectively. At the same time the noise monitors will be increased in number and some repositioned to achieve a significant improvement in their efficiency.

The new arrangements will come into effect on 1 January 1997. This was confirmed yesterday by aviation minister.

This follows a review, publication of a technical study (CS Report 9539), consultation and further data analysis. Announcing his decision, Lord Goschen said:

'On 3 October 1995 we issued a consultation paper proposing:

'(a) to continue to monitor the noise levels at the fixed monitors in Lmax dBA and to apply the limits to all departing aircraft except Concorde

(b) to reduce the daytime noise limit by 3 dBA and the night limit by 2 dBA, to 94 dBA and 87 dBA respectively

(c) to reposition existing and additional monitors in revised arrays, to achieve a substantial increase in monitoring efficiency (to about 50%)

(d) to review within two years the performance of any monitoring system in place following the outcome of this consultation, to determine whether a further substantial increase in monitoring efficiency can be achieved in practice

(e) to continue the review with the aim of identifying appropriate differential limits.'

'The consultation period closed on 23 February 1996. I have given careful consideration to all the responses received. The majority of the responses concentrated on the proposals to reduce the noise limits and to improve monitoring efficiency. There was a wide divergence of opinion between the airlines, airport and aviation bodies on the one hand and the local authorities and other local organisations on the other, over the proposed increase in stringency in the noise limits. There was little dissent from the proposal that monitoring efficiency should be increased, although there was less consensus on the appropriate target level.

'Our commitment to review policy on noise limits and to consider what improvements might be made dates back to the 1985 Airports Policy White Paper (paragraph 8.9). Work was deferred until BAA had installed new noise and track keeping systems at the airports. A technical study was then carried out analysing data obtained from the systems, as described in the consultation paper.

'The present noise limits have applied at Heathrow since 1959 and at Gatwick since 1968. The earliest jet aircraft were extremely noisy but developments in engine technology and the noise certification regime have led to considerable reductions in aircraft noise at source, weight for weight. Non-noise certificated aircraft have generally not been permitted to fly in the UK since 1988 and Chapter 2 aircraft are now being phased out. Shrinking noise contours show that over the years these measures have led to significant improvements in the noise climate around airports, particularly at Heathrow, despite the increase in aircraft movements.

'Against this background, many of the responses from those representing people living around the airports indicated that the reductions proposed in the noise limits for individual take-offs were too low. However Chapter 2 aircraft are legally permitted to operate until 31 March 2002. A daytime noise limit which most of the large long haul aircraft certificated to ICAO Chapter 2 standards could not meet in any circumstances would not be compatible with the UK's international obligations. As explained in the consultation paper and the technical study, that constrains the scope for reducing that limit.

'The majority of airline responses came from operators of long haul services, who expect to be the most affected by the proposals, and from the aviation organisations. In opposing the proposed reductions, some of these responses were concerned about the effect of the proposed noise limits on Boeing 747 aircraft. These involved highly technical points about climb performance, seasonal variation in aircraft heights and noise levels, and the effectiveness of noise abatement procedures. These points cast doubt on the validity of the findings of the technical study. I therefore sought further advice from the Department of Operational Research and Analysis (DORA) of National Air Traffic Services Ltd.

'DORA carried out some additional analysis of manufacturers' performance data, of Heathrow operational take-off weight data and of flight profile and noise data from the airport's noise and track keeping system which were relevant to the matters raised. The results of this further work are being published in a supplement to CS Report 9539. The supplement deals with points raised in the consultation: it is not intended as a comprehensive study of these factors.

'This further work supports the conclusions of the technical study on which our proposals were based. In particular, it demonstrates that the method used to assess the performance of the monitoring options accurately estimates infringement rates at Heathrow. It also indicates that, on average, variation in infringement rate for purely seasonal reasons will be small. It further indicates that the effects on noise of variations in take-off weight and meteorological conditions are expected to be rather less than those due to differences in operating procedures.

'The reasons for all the proposals were given in the consultation paper. The proposed reduction of 3dB in the daytime limit represents a halving of noise energy, which is challenging for operators of heavy aircraft. It is a smaller reduction in terms of loudness than was sought by local people. Nevertheless I am satisfied that the overall benefits will be worthwhile.

'The proposed reduction of 2dB in the night-time noise limit is intended to ensure that the limit will be broadly compatible with the night restrictions regime that also applies at Heathrow, Gatwick and Stansted and reflects what is operationally practicable in that context. No exact equivalence is possible as the noise classification of departing aircraft for the night restrictions regime relates to sideline as well as flyover noise and is based on noise certification data expressed in EPNL (effective perceived noise level) which reflects tonal quality and duration of sound that are not taken into account in the noise limits - measured in Lmax dBA.

'Taken together, implementation of the proposals should fulfil the objectives set out in the consultation paper. I have decided to confirm all the proposals put to consultation. They are to be implemented from 1 January 1997. This date applies both to the reduction in the noise limits and, as far as is practicable, to the repositioning and increase in number of noise monitors to achieve the increase in monitoring efficiency. It also determines the timescale for the review of monitoring efficiency. As explained in the consultation paper, and in the technical report, the combined effect of reducing the limits and repositioning the monitors to give a theoretical efficiency of about 50% should have the combined effect of raising the probability of detection (i.e. monitoring efficiency) above 50%. I am satisfied that it would not be practicable to seek yet further improvement in monitoring efficiency prior to the review.

'Broadly speaking, monitoring efficiency means siting the monitors in order to catch as many aircraft as possible that breach the noise limits. Or, in the language of the technical report, 'the percentage of offenders that are recorded as infringements at one or more of the monitors in the array'. The sites for the monitors are, of course, the subject of negotiation between the airport companies and local landowners. I am grateful for the co-operation of all those involved, including representatives from local communities, in identifying suitable sites and to BAA plc and the airport companies for undertaking to purchase the new monitors and to operate the enhanced system.

'The new noise limits that I have confirmed will be regarded as Base limits applying at 6.5 km from start of roll (about 3 km from the end of the runway). As described in the consultation paper, positional adjustments will be applied at each individual monitor to correct for the difference in distance between the actual location of the monitor and the 6.5 km point and for the height of the monitor position relative to that of the airport.

'The present requirements for aircraft to be at a height of not less than 1,000 feet when passing the nearest noise monitor and thereafter to employ thrust management to ensure progressively reducing noise levels at points on the ground under the flight path will continue to apply. These requirements are almost as old as the current noise limits but have been variously expressed in terms of height 'above airport level', 'above ground level' or undefined. To ensure consistency with the other arrangements I am confirming today, and with the way in which data is recorded in the airports' noise and track keeping systems, the minimum height requirement will be 1,000 feet 'above airport level' (not 'above ground level' as at present).

'The proposal to continue the review of the departure limits with the aim of identifying appropriate differential limits for less noisy types of aircraft met with a mixed reaction both from local representatives and from the airline industry. As I have confirmed, this review should continue as proposed. However, I am asking the Aircraft Noise Monitoring Advisory Committee (ANMAC), which will oversee the work, to give higher priority to the study into the feasibility of setting noise limits for landing aircraft, on which they are already engaged. This is consistent with advice given to me earlier by ANMAC. It also takes account of representations made by some local people and organisations in response to the departure noise limits consultation and in general correspondence.

'I am unable to refer specifically to all the points made in each of the responses to the consultation. I have therefore arranged for all the responses received within the consultation period to be made available for inspection (no author requested confidentiality). The responses will be in our Information Centre at Great Minster House for six months from the date of this notice.

'In addition, we have not lost sight of a commitment made in February 1988 to publish night noise contours. The principle of using noise contours to assess increases or decreases in daytime aircraft noise exposure is well established. The proposal in 1987 (confirmed in 1988) to publish night-time noise contours using Leq (equivalent continuous sound level) was supported by research. Leq is used for day-time contours but night-time contour bands have not been correlated with annoyance in the same way as daytime contours have, and there is no publicly accepted night-time scale or any agreed means of interpreting night-time contours. I have therefore decided to commission some further research on this subject to determine whether a method of interpreting night noise contours can be drawn from the conclusions of previous research both in this country and abroad. It would not be possible to carry out any reliable social survey work around our London airports now because findings might be prejudiced by the present Inquiry into the proposed Terminal 5 at Heathrow.

'In view of the proximity of his constituency to Heathrow, the transport secretary George Young has not been involved personally in the decisions I have announced today.'

-- Noise limits have applied at Heathrow since 1959, at Gatwick since 1968 (not 1974 as stated in the consultation paper) and at Stansted since 1993

-- Lmax dBA is the highest instantaneous soundlevel recorded during a noise event. The A-weighting approximates to the characteristics of human hearing

-- The Aircraft Noise Monitoring Advisory Committee (ANMAC) was set up in 1988. It is chaired by the department of transport and includes representatives of the Heathrow, Gatwick and Stansted Airport Consultative Committees, BAA plc and the three airport companies, the Heathrow, Gatwick and Stansted Scheduling Committees, the Civil Aviation Authority Directorate of Airspace Policy and the Department of Operational Research and Analysis of National Air Traffic Services Ltd

-- Chapter Two aircraft are aircraft certificated to standards introduced in 1970 by the International Civil Aviation Organisation under the Chicago Convention. Chapter Two standards were the first internationally recognised regime of noise standards for subsonic jet aircraft. Developments in technology allowed tougher Chapter Three standards to be introduced from 1977, and it was subsequently agreed internationally that Chapter Two aircraft would be phased out.

-- The study on which the review of the noise limits was based was conducted by the Department of Operational Research and Analysis, National Air Traffic Services. The work is reported in CS Report 9539, Review of the Departure Noise Limits at Heathrow, Gatwick and Stansted Airports by R E Cadoux and J B Ollerhead, obtainable from the Civil Aviation Authority, Greville House, 37 Gratton Road, Cheltenham, price £15. The supplement to CS Report 9539 will be available shortly from the same address, price £5.

-- People wishing to inspect the responses to the consultation paper should contact the Librarian at the Information Centre, Department of Transport, Great Minster House, 76 Marsham Street, London SW1P 4DR; Tel 0171 271 4324. A few days notice is required.

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