6. Conclusions, Danish Environmental Protection Agency

1998 Fuel Use and Emissions for Danish IFR Flights

6. Conclusions

This study has shown the feasibility of the new CORINAIR methodology for making city-pair aircraft emission inventories. Consistent data for individual flights and general classifications of aircraft types and airports exist together with fuel use and emission data for representative aircraft types. In this way EUROCONTROL provides information for individual IFR flights which correspond to essential data from ICAO on aircraft designators and airport codes. All data can be combined to build up the inventory system. In order to make the final grouping of aircraft into representative aircraft additional aircraft descriptions can be obtained from aircraft directories.

The new CORINAIR data bank consists of fuel use and emissions for several representative aircraft types. The data available was sufficient to underpin the fuel use and emission calculations in the inventory - both for LTO and for cruise at different flying distances. The established data bank is mainly a result of international co-operation. Not only in working groups set up in the CORINAIR framework but also in remote research networks and other working groups dealing with aircraft emissions. Here experts have participated, i.e. emission modellers, inventory makers and local airport traffic managers, together with EU experts.

Much time is needed to build an aircraft emission inventory following the new CORINAIR guidelines. Even though it would be less time consuming to make an inventory update each year, the working time required will exceed the time typically available for inventories. Therefore it is recommended to maintain the current methodology for national emission reporting. Instead of a shift to the new model version, one should make an update of the current model’s background data for fuel use and emissions.

Real improvement of the current version for LTOs - except for international LTOs in Copenhagen Airport – could be achieved by applying new LTO fuel use and emission factors derived from the new methodology as aggregated figures. For cruise it is recommended to break down the fuel use between Copenhagen Airport and other Danish airports according to their LTO fuel use estimates. Also the cruise emission indices should be updated. Both for domestic and international flights these can be derived from the new methodology results. The new CORINAIR LTO and cruise data can also be used to make time series estimates of fuel use and emissions since new aircraft/engine combinations only have a slow speed of penetration in the aviation sector.

It is recommended to use the TEMA2000 numbers if fuel use and emissions are evaluated for those domestic trips flown with the aircraft comprised in TEMA2000. For domestic emission inventories the CORINAIR data should be used primarily because of data consistency and because CORINAIR contains data for small jets and turbo-props not present in TEMA2000. The latter reason fully compensates for the inaccuracy in results for some aircraft due to model boundary conditions.

This study’s findings clarify the need to further scrutinise for which purposes the aviation fuel is used in Danish Airports. A way to do this is to examine the most detailed data on aviation fuel delivered to the airports. Also the airport authorities on aviation fuel supply should be asked and their information should be verified by analysing other data available. Even though the fuel sale statistics have been improved after the finalisation of the present project the present study’s result could be valuable in a crosscheck examination of statistical data versus model estimates.

A double check on the fuel use from the CORINAIR databank with experiences from real world operation of aircraft during landing, taxiing, take off, climb out and cruise flying conditions would also add to more precise fuel balances in future aircraft emission inventories. To make these comparisons information must be obtained from the airline companies on fuel use figures for the aircraft most frequently operating from Danish airports.