Honeywell and Boeing Seek Improved Contrail Assessments

Honeywell and Boeing are teaming with the UK’s University of Reading to develop a new type of aircraft-based sensor they say could improve understanding of contrails and their climate impact. Project Mist, announced on March 18, has received funding from the Aerospace Technology Institute, which is backed by industry and the UK government.

The focus of the work is to improve in-flight atmospheric sensing capabilities to increase the accuracy of contrail forecasting and enhance weather modelling. The partners did not say when or how they intend to start flight trials with new technology resulting from the project.

Contrails are clouds of ice crystals formed when hot, humid jet engine exhaust mixes with very cold air at high altitudes. According to the partners, current humidity sensors have limited measurement capabilities and are not widely used on commercial aircraft that could be collecting data. Alternative technologies are available, but these can require significant redesign work to be deployed by airlines.

Honeywell is responsible for Project Mist’s sensor hardware integration and systems integration tasks, building on the group’s extensive experience with sensing technologies for aircraft. The company’s site at Yeovil in the UK is directly involved in the work.

Boeing’s contribution to the project involves aircraft integration, testing, and operational expertise to evaluate sensor performance. This work will be led by the airframer’s team in Bristol, UK, supported by colleagues from Seattle.

The University of Reading’s Department of Meteorology is contributing its experience with contrail modeling and climate analysis. It has been involved in research into the climate impact of aviation for more than three decades, in part through its involvement in European initiatives looking at the impact of emissions other than carbon dioxide—for example, EASA’s Aviation Non-CO2 Expert Network.

French Airline Trials Contrail Avoidance

In related news, Thales and French charter flight operator Amelia this week announced they have expanded contrail-avoidance trials that started in 2024 on flights between Paris and Valladolid in Spain. Thales has helped the airline to modify the altitudes at which its aircraft fly to avoid contrail formation without the need to change routes and burn more fuel.

In 2025, Amelia started using the Thales flight planning tools on its fleet of Airbus A319/320 and Embraer ERJ-145 aircraft. The partners reported on March 19 that over the course of the year, this initiative—which is part of the French government-backed Decor program—reduced the average climate impact of each flight by around 70%.

Amelia’s approach has been to focus its mitigation efforts most on the relatively small number of flights in which contrail formation is most persistent and the greatest climate warming impact is caused. Using modeling developed with Thales, the operator said that it has avoided between 2,000 and 2,500 metric tons of CO2-equivalent emissions during 2025 alone. This outcome was achieved from making altitude adjustments to just 59 out of 6,400 flights operated last year, while incurring less than 0.1% increase in fuel consumption as a consequence of the changes.

“By targeting high-impact flights, we remove the barrier of scientific uncertainty about the magnitude of the phenomenon and focus on immediate action,” commented Adrien Chabot, Amelia’s director of sustainability.