From the deafening silence of the experts other than Denti (whose input is as always interesting) it seems that noise abatement does not seem to be of much concern to most people or perhaps somebody can explain why increasing noise at the abatement point is not a problem.
I appreciate this will vary by aircraft type and airport. But assuming a non weight limited 737 departure in the early hours of the morning selecting derate 2, max assumed, improved climb and then accelerating at 1500 feet or lower does not seem to make sense from a noise abatement point of view.
The first segment of the takeoff will take much longer and the point that the aircraft reaches 35 feet will be much closer to the departure end of the runway. The second segment, whilst meeting the 2.4% climb gradient, will be performed at a thrust setting that may be well below minimum climb thrust and will therefore reach acceleration height further away from the airport.
I am also not getting any real benefit from the improved climb as I accelerate at or before the point where the improved climb path crosses the non improved climb path. At this point we increase power and clean up all of which increases the nuisance to those living close in to the airport.
Gut feel would suggest that if I use a takeoff thrust setting equivalent to minimum climb thrust and climb to acceleration height closer to the airport, even possibly climbing to 3000 feet before cleaning up, I will reduce the noise impact to those along the departure path. Again if anybody knows of any studies that throw light on this I would be most grateful.
Last edited by lederhosen; 7th July 2012 at 10:43.