Advisory Council on the Environment

Situation Report on Aircraft Noise

(ACE Paper 44/98)
for information

Complaint on Aircraft Noise

Since the opening of the new airport on 6 July there have been complaints from residents living under the flight paths about aircraft noise. As at 7 October, a total of 859 complaints on aircraft noise have been received. Most of the complaints received in the first 2 months were from residents living in areas under the arrival flight path of Runway 25L such as Shatin, Tsuen Wan, Kwai Chung and Tsing Yi (see Annex A). The number of complaints has shown to drop significantly from about 300 in the first week to only 15 in the ninth week.

However, starting from mid September when the major wind direction at the airport changed from the south/southwest to the northeast and east, Runway 07 has mostly been used and the number of complaints has risen again. Most of these complaints are now from residents living in areas close to or under the departure flight path of Runway 07R such as mid-levels, Causeway Bay, North Point, Quarry Bay and Chai Wan (see Annex B). However, we expect to see these complaints coming down to a steady level.

It has been observed that a vast majority of complaints came from residents who have not previously been exposed to aircraft noise. The humming noise of aircraft flying at an altitude of about 4500 ft at Shatin, 3500 ft at Tsuen Wan, 3000 ft at Tsing Yi and over 4000 ft at North Point is considered by them as a nuisance. The complainants are mostly concerned with the new flight paths which did not exist in the past.

Attached at Annex C is a table showing the number of complaints received from various districts. A diagram showing the profile of daily complaints figures since airport opening is given in Annex D.

Noise Measurements

CAD together with EPD have conducted noise measurements in areas under the flight path. The measured noise levels are summarized as follows:-

Based on the measured noise data, we have worked out the preliminary NEF figure for the affected districts as follows:-

The above results indicate that with the exception of Sha Lo Wan, all other residential areas are outside the NEF 25 contour. This is in line with the forecast by the EIA.

Interaction with the Public

Some of the noise measurements mentioned in paragraph 4 above were conducted together with residents and members of the Provisional District Boards. Moreover, briefings on aircraft noise and flight paths have been given to Kwai Tsing, Shatin, Tsuen Wan, Central & Western and Kowloon City Provisional District Boards. Further briefings to Wanchai, Eastern, Southern and Yau Tsim Mong Provisional District Boards will also be given shortly.

Change of Flight Path

The flight paths for the new airport were developed through careful studies in accordance with international standards and recommendations. Their development took into account runway alignment, terrain environment and obstacle clearances, location of navigation aids, aircraft operating criteria, noise consideration, airspace co-ordination with nearby airports, etc. Hong Kong is small in size but hilly in topography. It is not possible to design a flight path that is in compliance with international aviation safety requirements on the one hand and completely clear of all residential developments on the other. When CAD appointed international aviation experts to assist in the detailed planning of the flight paths for the new airport in 1994, various factors had been taken into account and in-depth study conducted before the existing ones were drawn up. In view of airspace constraints and flight safety consideration, the existing flight paths cannot be altered.

The time and frequency of using the Runway 25 approach track or Runway 07 departure track will depend on the wind direction and strength. When the wind on the runway of the new airport is from the southerly or westerly direction, aircraft will have to use the Runway 25, i.e. landing from the northeast and taking off to the southwest of the new airport. In summer, when Hong Kong is under the influence of the southwest monsoon, the chance of using Runway 25 is much higher. However, in winter and spring when the major wind direction is from the northeast and east, Runway 07 will mostly be used, i.e. aircraft will land from the southwest and depart to the northeast of the new airport. According to past meteorological data, the utilization of each runway is expected to be evenly split.

Measures to Reduce Aircraft Noise

To address the public concern, the following measures have been implemented:-

Second Runway and Its Impact

When the second runway becomes operational, the airport will initially be operated in a segregated mode, i.e. the southern runway dedicated for departures and the northern runway for arrivals. In future years, when more operational experience is gained and the air traffic demand increases, an integrated mode of operation, i.e. both runways used for departures and arrivals, will be adopted. Under the segregated mode of operation, the new arrival flight path of Runway 25R (which is parallel to Runway 25L but at a distance of about 1.5 km to the north) will overfly the residential areas in Kau To Shan, West Tsuen Wan, Ting Kau, Sham Tseng and Tsing Lung Tau (see Annex E). It can be expected that upon the operation of the second runway, the noise impact on residents under the current arrival flight path of Runway 25L would be reduced, while residents living under the new arrival flight path of Runway 25R would become affected. However, the extent of impact of the newly affected residents is expected to be more or less the same as the present situation.

Way Forward

The new airport is designed for 24-hour operation in order to cope with the demand of air transport and maintain Hong Kong's status as a centre of international and regional aviation. Except a small number of residents in North Lantau, other noise sensitive receivers are outside the NEF 25 contour and this is in compliance with international environmental standards. For this reason, the Government has no intention to restrict the taking off and landing of aircraft at the new airport.

In order to alleviate the noise nuisance to the public, the following actions have been or will be taken by CAD and/or the Airport Authority:-

Civil Aviation Department
October 1998