CONFIDENTIAL
no
For example, the 25 dB contour for a flight track with nighttime operations is equivalent to a contour with 10 night activity of value
percent
L
25
= 29.1
10 log ((1 + 15.7 x 0)/2.57) dB
(D-9)
Since contour sizes are reduced as noise values increase, this result shows that the elimination of night flights reduces the contour significantly (by 4.1 dB).
2.3 APPROACHES AND DEPARTURES
Adding the exposures from approaches and departures is similar to adding exposures from two diverging tracks. Since departures are generally noisier than approaches, the overall contour around a flight track with both operations is not much different than that of the departure contour alone.
2.4
ADJACENT RUNWAYS
on
Where contours from one runway overlap those of a neighboring runway, the values are summed as in Equation D-5. In the case of Scheme "B", with approaches and departures in each direction two runways the resulting 8-fold summation is quite complex for hand analysis methods. Therefore, the precise location of the overall contour close to the runways must be considered somewhat more approximate than locations farther along the flight track.
3.
3.1
>
ADDITIONAL NOISE CONSIDERATIONS
SINGLE EVENT
Ideally, to provide a better understanding of the noise environment in the Deep Bay area, an analysis of the single event noise levels should be developed. Time constraints prohibited a computer analysis of single events, but some general observations can be made.
In the Fairview Park area, given no restrictions, the aircraft flying closest and lowest to the development would be the heavy B-747's. If this aircraft used the entire runway for a northeasterly departure and climbed to an average (slow) rate of 6 percent through the turn, then it would be at an altitude of about 700m (2300 ft) at a point near the western edge of Fairview Park, about 10.5 km from brake release. At this distance the Effective Perceived Noise Level (LPNE, See 2.1 of this
>
Appendix) is approximately 94 dB, according to Appendix C, Volume 4, Reference 1. This corresponds to a maximum outdoor A-weighted level of about 75 dB, using the relationship described in Reference 3, or the equivalent of a high speed car pass by observed 15m (50 ft) from the roadway.
9-7
CONFIDENTIAL