For a given timeframe and airport, CLAIRPORT's basic assessment principle is to compare the environmental performance of two aircraft-traffic scenarios. The first scenario is a one-day flight schedule with Clean Sky 2 reference-technology aircraft in the relevant classes (long-range, short-/medium-range, and regional). The second scenario uses the same flight schedule, but in which (based on fleet replacement rates) Clean Sky 2 concept aircraft replace their reference-technology counterparts. The approach to quantify the environmental performance of an aircraft-traffic scenario consists of two steps. Firstly, a realistic simulation of aircraft traffic is conducted, yielding for each flight a complete trajectory in the airport’s local airspace. Secondly, the environmental contribution (in terms of noise, CO2 and NOx) is calculated per flight, based on its trajectory. These environmental contributions per flight are then aggregated to obtain the total environmental-impact results at airport level. These steps are elaborated below.
1. Airport selection
To conduct assessments for a representative set of European airports and a generic airport, CLAIRPORT developed an airport-selection scheme. The first step is a categorisation of airports. The second step is a set of criteria for selecting airports from every category in this categorisation. Based on this scheme, CLAIRPORT selected Amsterdam Airport Schiphol, Rome (Leonardo da Vinci –) Fiumicino Airport, Stockholm Arlanda Airport, Hamburg Airport and Toulouse Blagnac Airport, as well as the generic airport CAEPport.
2. Simulations and calculations
For each aircraft-traffic scenario, CLAIRPORT firstly conducts a realistic simulation of aircraft movements at and around the airport. The simulation output contains for every flight a complete trajectory in the airport’s local airspace respecting the real airport operational procedures and rules. These individual trajectories are subsequently processed by noise and emissions models to calculate the associated noise and emissions. Depending on the aircraft type, either a model from industry (for its reference-technology or Clean Sky 2 concept aircraft) or from Royal NLR (for other aircraft than reference-technology or Clean Sky 2 concept aircraft) is used. In the final step, the individual noise and emissions results are aggregated to yield noise and emissions output per aircraft-traffic scenario. Consistent with EU Directive 2002/49/EC and ICAO Doc 9889, this output includes:
- Lden and Lnight contours for significant noise levels: Surface area and population exposed;
- Total amount of CO2 and NOx emitted below 3,000 ft.
Capitalising on the framework from the earlier Clean Sky TE project (2008-2016) for assessments at airport level, CLAIRPORT developed an efficient and effective computation framework to carry out these simulations and calculations.
3 Assessments
CLAIRPORT carried out assessments up to 2050 for the selected airports in Step 1 in accordance with the process described in Step 2. These assessments show substantial improvements thanks to Clean Sky 2 technologies for fixed-wing aircraft. The reductions for 2050 in surface area of Lden contours for relevant noise levels (60-65 dB(A)) are about 10-15%, and for these noise levels, the reductions in population exposed are about 10-25%. In 2050, reductions of CO2 emissions amount to about 8-13.5% for the European airports considered, while the associated NOx reductions are in the range of 6.5-10.5%.
The assessment results are presented through various means, including the Clean Sky 2 TE publication 'First Global Assessment 2020' and presentations at various conferences.
