TNAG-1174-FCO40-1476-Proposed-replacement-airport-for-Hong-Kong-at-Deep-Bay-or-Ch-1982 — Page 141

APPENDIX D

DERIVATIONS OF NOISE CONTOURS

CONFIDENTIAL

1.

ASSUMED 1995 OPERATIONS

The study year selected for this study is 1995, which is expected to be the fifth year of Replacement Airport operation. Average daily operations during the busiest month of this year, which are assumed to represent 9% of annual operations, are defined to be the Design Day. Derivation of forecast operation details are presented in a previous consultancy report on the Replacement Airport at Chek Lap Kok (Reference 1). The detailed breakdown of operations by aircraft type and time of day are briefly discussed

here.

1.1

AIRCRAFT MIX

The

Table 9-1 illustrates the number and type of each aircraft which were projected to use the airport in Case 6 of the previous study. Departures are divided according to the distance to the aircraft's destination (stage length). Because of the required quantity of fuel, the stage length is the primary factor governing the total gross weight of the aircraft at takeoff. difference in gross weight results in a substantial difference in the noise levels generated during takeoff but no significant difference during landings. Because of the annualized nature of the noise exposures, fractions of flights are shown in the aircraft mix tables to reflect the aircraft and track percentage distributions expected to Occur over a longer period of time. For this Deep Bay airport study, only the flight track percentages were changed. The stage length and aircraft mix assumptions remained

same.

C

use

The aircraft types that are projected for cargo and passenger in the 1995 Hong Kong market include: B-757, DC-9-80, B-767, A-310, DC-10, L-1011, A-300, B-747, and B-747 (S). The Integrated Noise Model (INM), which was employed to make initial noise exposure estimates, contains within its data base the noise characteristics of these aircraft except the B-757, B-767, and A-310, which represent a new generation of quiet aircraft, along with the A-300B and the DC-9-80. A good representative for these models appears to be the A-300B, a two-engine, wide-body aircraft with high-bypass ratio engines similar to those used in the other models. The noise characteristics of this aircraft should be very similar to those expected for the A-310 and the B-767, but they are likely to be slightly noisier than the B-757 and DC-9-80, which have a a somewhat smaller fuselage and, hence, lower passenger capacity and total weight. Since the latter two models are projected to represent less than 20 percent of this new generation two engine aircraft fleet, it is thought appropriate to assign all aircraft movements associated with the five future aircraft the noise data characterized by aircraft No. 20 in the INM data base (A300B).

9-1

CONFIDENTIAL