The impact of changing fleet makeup on airline noise emission

With the advent of the Environmental Noise Directive (END) population level modelling of exposure to aircraft noise has increased within Europe. Present noise exposure legislation focuses on airports whereas the greatest potential to implement noise reduction technologies lies with the airlines and aircraft manufacturers. This work focuses on the modelling the noise emission of the fleet of Europe's largest airline by passenger numbers, Ryanair. The noise reduction achieved at a fleet level will be evaluated and the impact of changing fleet makeup assessed. The airline's current fleet consists of 409 Boeing 737-800 aircraft and 29 Airbus A320-232 aircraft, while 210 new Boeing 737-8200 max aircraft are on order. The new aircraft have a 40 % smaller footprint in the 85dB(A) noise contour during take-off than the existing 737-800. The 85dB(A) contour of 737-800 stretches out around 4.5km along the runway, while the contour of 737-8200 max was reduced to ca. 2.5km. This is achieved by implementing new winglet design and more efficient power units, which operate with lower fuel consumption (and thus lower aircraft weight), less carbon emissions, and lower noise emissions. The impact of this change to the fleet is evaluated using a representative airport modelled in SoundPLAN. Noise contours generated with SoundPLAN show the noise effects of the different aircraft types of the historic, current and future Ryanair fleet under realistic operating conditions. Different departure profiles are investigated, depending on the aircrafts weight, altitude, speed, and thrust profile. The generated noise contours provide an evidence base for decision making within the airline for investments aiming to reduce noise levels around airports. The potential for reducing population exposure to noise under the framework of the END is presented.