Night flying restrictions is any regulation or legislation imposed by a governing body to limit the ground-perceived exposure to aircraft noise during the night hours, when the majority of residents are trying to sleep. Such regulations may include restrictions to available flight paths, or prohibitions against takeoffs, or prohibitions against takeoffs and landings, or prohibitions against ground operations (engine runups or taxiing).
Night flying restrictions, commonly known as curfews, are common at airports in Europe.
The night restrictions for Heathrow, Gatwick and Stansted define a night period, 2300-0700 hours, and a night quota period, 2330–0600 hours. During the night period, the noisiest types of aircraft (classified as QC/4 QC/8 or QC/16) may not be scheduled to land or to take off (other than in the most exceptional circumstances). In addition, during the night quota period movements by most other types of aircraft (including the new QC/0.25 category) will be restricted by a movements limit and a noise quota, which are set for each season.[1]