Options for Assessing the CO2 Intensity of Commercial Aircraft under an Airframe Standard

There is considerable interest within ICAO and member states regarding options to set CO₂ or GHG emission standards for commercial aviation.This paper identifies several possible carbon intensity metrics suitable for use in a CO₂ standard for new commercial airframes, and evaluates those metrics relative to simple design criteria. It demonstrates that previous inconclusive ICAO work on efficiency metrics, which was specific to in-operation aircraft, does not preclude the establishment of a CO₂ standard for new aircraft. Setting an airframe CO₂ standard should be less technically challenging than ongoing efforts to set equivalent standards for other transport modes, notably heavy-duty vehicles and oceangoing vessels, that have greater diversity of duty cycle and vocation.