Aircraft operating at DIA have a diverse range of noise levels. These noise levels primarily depend on the type of engine used by the aircraft, the size of the aircraft and whether the aircraft is taxiing on the airfield, landing or taking off. Current versions of Stage 3 aircraft tend to be the quietest aircraft in the fleet. Older Aircraft with Stage 3 "hush kitted" engines tend to be the loudest. Departures tend to be louder than arrivals since the pilot is using more power to the engine to achieve lift.