To use the Tier 2 method, the aircraft types used for both domestic and international flights, as well as the number of LTO’s carried out by the various aircraft types, must be known. If this information on a per aircraft type basis is not available, it is recommended that the Tier 1 method be used.
The Tier 2 Approach breaks the calculation of emissions from aviation into 4 steps:
Step 1: Estimate the total fuel consumption for domestic and international aviation
Step 2: Estimate the fuel consumption for LTO activities by aircraft type
Step 3: Estimate the fuel consumption for cruise activities by aircraft type
Step 4: Estimate the emissions for each gas