Airbus and a consortium of 10 partners from four European countries this week launched a study to assess the impact of non-CO2 emissions on local air quality and climate. The research program, called Particle emissions, Air Quality, and Climate Impact related to Fuel Composition and Engine Cycle (PACIFIC), was announced on Tuesday at the Airbus Summit in Toulouse and will focus mainly on contrails.

According to Mark Bentall, head of research and technology programs at Airbus, the PACIFIC project will use an A350 aircraft and its Rolls-Royce engines for ground tests to assess how different fuel mixes impact contrail formation. He said this approach, in which a controlled environment can be maintained, will provide more extensive data than that gathered from previous flight tests with an A320 jet.

Program partners aim to test the theory that the use of various blends of sustainable aviation fuel could reduce soot particles and the ice crystals that form contrails. The new approach to testing is intended to ensure consistency in combustion parameters and hardware similarity based on lab-scale experiments at Germany’s DLR aerospace research agency and full aircraft engine tests conducted by Airbus in Toulouse.

Research will focus on understanding how soot forms during fuel combustion and establishing how predictive tools could more effectively anticipate when and how it will be part of aircraft emissions. Tests will analyze the quantity of fine particles released with an engine running at different power levels.

How To Mitigate Contrail Impact

The PACIFIC partners are aiming to develop a more reliable cost-benefit analysis of various aircraft fuel options that could support decisions around fuel regulations. Results should give a broader understanding of the climate effect of contrails and how the formation of these can be changed with different combinations of engine settings and fuel use.

“It is the uncertainty [about contrails] that makes them hard to mitigate,” Bentall told the Airbus Summit. “But there is good consensus that contrails have a net-warming effect [on the climate] and so we need to take them seriously.”

According to Tim Johnson, director of the Aviation Environment Federation, policy members need to have greater certainty over the science behind contrails to avoid unintended consequences with possible new regulations that might, for instance, increase the impact of CO2 emissions. “We could make a big difference quickly by doing something about contrails, because it would take a lot of CO2 reduction to get the same climate change benefit,” he commented.

In November 2024, NASA and GE Aerospace launched their joint Contrail Optical Depth Experiment to get a better understanding of how contrails form. The partners are using NASA Langley Research Center’s Gulfstream III to trail GE’s Boeing 747 flying testbed, using Lidar technology to scan contrails to produce 3D imaging.