Which ordinance must airports within or close to Orange County, California abide by? What actions do commercial pilots take concerning their engine noise when arriving or departing Orange County, California? Does #1 and #2 require that their airplanes make less noise?
Orange County, California
John Wayne Airport is in Orange County. John Wayne Airport is in very close proximity to residential areas. There is a General Aviation Noise Ordinance in Orange County, California.  Commercial pilots will cut the engine of the aircraft on arrival and departure from Orange County, California. 
County in California, United States
Does Orange County, California require airplanes to be quiet?