The results of a comparison between preliminary data from the AERO model and the latest available inventory information from Annex I Parties in relation to fuel consumption and CO2 emissions data for domestic and international aviation are presented and discussed. Although the comparison shows relatively good agreement in total fuel consumption and CO2 emissions across all Parties considered, there are large differences between UNFCCC and AERO data for a number of Annex I Parties. An update on the work being undertaken by the International Civil Aviation Organization (ICAO) and brief descriptions of two new models (AERO2K and SAGE) that are currently under development by ICAO are also provided. Initial results from these two new models are expected in spring 2004