Scientific evidence suggests that the presence anthropogenic (human generated) clouds (i.e., contrails) contributes an estimated ~2% of total anthropogenic net radiative forcing (NRF) leading to global heating and it may account for approximately half of aviation’s overall contribution.

There is some uncertainty associated with the magnitude of the NRF and scientists are actively working to reduce this uncertainty.

There are several approaches to reducing the presence and NRF impact of contrails ranging from fuel adaptations, jet engine re-design, fuel additives, and alternative forms of aircraft propulsion. These approaches require additional research, testing, certification, and time to implement.

One approach that can reduce the presence of contrails in the very near future is to adjust the cruise levels of flights that are planned to traverse atmospheric conditions known as Ice Super Saturation Regions (ISSRs).

Studies have shown that on an average day, only 15% of the flights in the CONUS traverse an ISSR and generate contrails. Further, a 1000’ or 2000’ increase in Cruise Flight Level can reduce the presence of contrails by more than 67%. Further the cost of additional fuel burn for the additional climb is less than 1% and in many cases is washed-out by the Cruise at the more optimal Cruise Flight Level.

Implementation of control avoidance through Cruise Flight Level changes is an operational change that could be implemented at relatively low cost in a short space of time.

NOTE: In contrast to CO2 emissions that take 20-40 years to affect the climate, contrail avoidance has an immediate effect.

As the scientists work to reduce the uncertainty in the magnitude of the contrail contribution to climate change, it behooves the air transportation community to plan for a day when contrail avoidance might be implemented. What additional information is needed to develop a mitigation approach?  What incentives/policy changes may be required?  What operational changes need to be implemented?

The Workshop provided a forum for an open exchange of ideas and information regarding the emerging needs associated with contrail avoidance in the National Airspace.

The Workshop addressed:

• Stakeholders impacted
• Operational Procedures for all stakeholders through-out the life-cycle of a flight plan
• Data sharing requirements
• Scientific Models required and accuracy requirements
• Contrail reduction verification
• Design of pilot projects
• Safety and Security
• Policy implications

This initial workshop did not result in a definitive mitigation approach but led to recommendations on how the community can collaborate together to pursue such an approach with the potential creation of a continuing interest group.

• DATE: Wednesday, September 7, 2022
• TIME: 12PM - 5PM ET (9AM - 2PM PT)
• AGENDA: Available Here (for reference)​

Have additional questions? Email: arc-cal-nari@mail.nasa.gov