Socially undesirable airport footprint
Aircraft noise is environmental pollution. Advances in the quietening of aircraft are entirely negated by increases in the number of aircraft and longer airport operating hours. The main factors determining the nuisance are the noise peak levels, the frequency of disturbance and the time of day.
Near Heathrow airport in the UK more than 700,000 people live above reasonable level of 35 noise units. Brussels is the only EU capital airport that allows night flights.
During the past 20 years, the area (footprint) affected by intrusive noise from the typical new subsonic aircraft has been reduced by 90%.