Topic: | Re:Re:Re:Re:Re:Re:Re:Re:Re:Re:Re:Re:Re:Re:Re:Re:3rd runway noise in Chiswick | |
Posted by: | Jeff Gear | |
Date/Time: | 09/02/08 12:28:00 |
Thanks Tom. Not sure I understand why this would be:- "As far as dB is concerned, the effect is simply quantified (though it takes a little maths to derive the general formula): if two flight paths differ by 4 dB, an additional plane will add 10 to the power of 4/10, or 2.5 times the amount to the Leq of the quieter flight path compared to the noisier one." If it's only a little maths... "In general to minimise the logarithmic sum, and hence the Leq, you want to concentrate noisy planes on noisy runways." - makes sense, but not good news for those in the vicinity of the noisiest runway! "If the three runways were given the same mix of planes, the restriction on Leq contour area would actually mean Heathrow would have to contract!" - relative to what? |