The question that needs to be asked is "Was the airport there before you bought the property you are trying to protect from noise?"
The airport was, but the third runway was not.
The curfew was designed in 1994 and was a product of Labour dominated local, state and federal governments around the airport and inner city at the time.
Transport Minister at the time was Laurie Brereton with as a big a conflict of interest as you could imagine.