A new analysis of commercial aircraft fuel efficiency from the International Council on Clean Transportation (ICCT) finds that the UN’s aircraft CO₂ standard lags current technology by more than a decade.

The ICCT first analyzed the historical trends in fuel efficiency improvement of new commercial jet aircraft in 2009. In 2015, the organization updated the study and refined the analysis by using the UN’s International Civil Aviation Organization’s (ICAO) cO₂ metric value (MV).

Average margin to ICAO’s CO₂ standard for new aircraft, 1980 - 2019. Source: The ICCT

The new anaysis updates the previous work by taking into account new aircraft types and deliveries from 2015 to 2019, and by including dedicated freighters delivered from 1960 to 2019.

The authors followed the general methodology of the 2015 paper and assessed fuel burn via both block fuel intensity in grams of fuel per tonne-kilometer and the MV, which aims to provide a “transport capability neutral” means of regulating aircraft fuel burn.

The average aircraft fuel burn reduction stagnated in the 2000s; this latest analysis shows a return to 1% or more average annual reduction rate in the most recent decade. This is largely attributable to the introduction of various new, more fuel-efficient narrowbody and widebody aircraft models, the authors said.

Key findings of the report include:

1. New aircraft in 2019 were already on average 6% more fuel efficient than required by the ICAO standard in 2028. Advanced new types are even better, passing the standard by 10 to 20%. The average new commercial jet delivered in 2016, the year that ICAO’s standard was finalized, already complied with the 2028 requirements.

2. From 1960 to 2019, the fuel burn of new aircraft fell by between 1.1 and 1.3% per year, depending on the metric. However, manufacturers could do even better. A comprehensive technology assessment concluded that the rate of fuel burn reduction for new aircraft could be accelerated up to 2.2% per year through 2034.

3. ICAO should update the standard as soon as possible to provide incentives for technology innovation and adoption. Flexibility mechanisms like averaging and banking, which allow standards to be set based upon the performance of the best rather than worst aircraft, should be incorporated into future rules.

Despite the fuel efficiency improvements, total CO₂ emissions from commercial aviation have nonetheless increased alongside this trend. Meaningful aircraft emission standards will be pivotal for managing the climate impact of aviation, the ICCT said.