Contrails.org is requesting proposals from airlines, Air Navigation Service Providers (ANSPs), technology providers, and other entities to run navigational contrail avoidance trials. Through the Contrail Clearing Accelerator (CCA), Contrails.org will contract with selected participants to carry out trials and pay for the trial work and flight data it produces, on the terms below. The request is open to any operator worldwide. Proposals for the current phase will be accepted until January 31, 2027.
1. Background and Objectives
Persistent contrails account for roughly 1–2% of global anthropogenic radiative forcing, and this warming is highly concentrated: about 2% of flights globally cause roughly 80% of contrail warming. Minor altitude or flight-path adjustments on these high-impact flights, known as navigational contrail avoidance, show promise to substantially reduce this warming at low cost. Contrail forecast tools are already available for testing in some commercial flight planning systems.
The CCA is a research program housed at Contrails.org, a US 501(c)(3) nonprofit. It contracts with operators to run contrail avoidance trials, pays for the trial work and the flight data it produces, verifies the flights flown, and publishes the results. Through this request, the CCA aims to:
- Trial contrail avoidance with new airlines and flight planning systems.
- Support ANSP-led airspace-wide trials.
- Generate the operational data needed to answer key questions related to contrail avoidance.
Key open research questions include:
- How effective are current and proposed approaches for reducing persistent contrail formation and associated warming?
- What are the costs associated with contrail avoidance during real-world operations, and how can technological and process improvements increase cost-effectiveness?
- How can contrail avoidance be integrated into airline and ANSP operator workflows to enable avoidance at scale?
- What are the most effective methods for integrating contrail forecasts into pre-flight trajectory optimization and in-flight re-optimization?
- What are the most effective communication methods to present contrail regions to flight planners and pilots?
2. Trial Priorities
Proposals should advance scientific and operational understanding of contrail avoidance, the scale of its adoption, or both. Trials that apply a standardized methodology at scale are as valuable as trials that explore new conditions. Our current priorities, updated October 2026, are:
- Integrated airline and ANSP trials
- Flight planning systems not yet integrated with contrail forecasts
- High-density airspace
- Trials with high density (or multi-modal) observations
- Default-on operations (“Avoidance by default”)
We also welcome trials that expand learning in any of the following areas:
- Region: New geographic regions, airspace, or routings.
- New operators: Airlines or ANSPs new to contrail avoidance.
- Integration: Flight planning, dispatch, electronic flight bag, or air traffic management systems not used in previous trials.
- Avoidance strategy: New approaches, such as tactical avoidance, changes to trajectory optimization factors, or novel flight selection criteria.
- Human factors: Effects on planners, dispatchers, pilots, controllers, network managers, and others.
- Scale: More avoidance flights, or a higher rate of avoidance over a period.
This request is for navigational contrail avoidance trials. Trials of other methods of contrail avoidance, including changes to flight schedules, aircraft or engines, or fuel composition, are out of scope.
3. Proposal Process
Proposals may come from a single organization or a team. Selection has two stages. In the first, proposers submit a short proposal of no more than five pages covering:
- Team and roles: The participating organizations and the responsibilities of each.
- Scope: The routes or airspace involved, the approximate number of flights or volume of traffic that could be included, and the proposed period.
- Systems: The flight planning, dispatch, or air traffic management systems to be used, and whether contrail forecasts are already integrated.
- Data: The flight and fuel data that can be shared (see Data Terms).
- Costs: An estimate of readiness costs and, for ANSP-led trials, ANSP costs (see Costs and Payment).
In the second stage, Contrails.org scientists work with each shortlisted team to develop a full trial plan, including flight selection, the comparison or control design, the contrail forecast model, the expected impact, and the analysis and publication plan. Contrails.org offers this support to every shortlisted team at no cost. The trial plan forms the basis of the contract.
4. Implementation, Verification, and Safety
Safety and compliance with air traffic control instructions take precedence over contrail avoidance at all times. Participants keep full responsibility and authority for all operational and safety decisions and carry out avoidance within their existing safety management processes.
Before trial execution begins, Contrails.org will confirm with the project team that contrail avoidance tools have been integrated and that relevant personnel have been trained.
During and after execution, Contrails.org and the project team will cross-check planned avoidance routes against flown trajectories and use observational data and modeling to confirm that correct procedures were applied. Participants will be assessed on effort and correct use of avoidance tools, not on the success of individual avoidance routes, given weather and operational constraints.
5. Data Terms
For each avoidance and control flight, Contrails.org requires as a minimum the normal (nonavoidance) flight plan (or plans), the avoidance flight plan where one is produced, the flown trajectory, and actual fuel burn. Records of avoidance decisions should be included where available. Formats and delivery schedules will be agreed during contracting. Payment depends on delivery of this data. Participants that share data beyond these requirements may be eligible for a data-sharing bonus.
We protect participants’ commercially sensitive data. It is used only for verification and research, shared with our research partners only under the same confidentiality terms, and covered by a non-disclosure agreement where a participant needs one. We publish research findings, not participants’ data. Results are aggregated or anonymized unless a participant agrees otherwise, and participants are invited to contribute as co-authors. Before release, participants have 30 days to flag confidential information for removal. The names of participants and the total amounts paid to them may be made public.
6. Costs and Payment
Contrails.org pays reasonable costs for three things:
- Flight payments. A payment for each verified avoidance flight to account for extra fuel burn due to contrail avoidance. This only applies to airline-led trials. The methodology to determine extra fuel burn will be established during the second stage of the proposal process. Any methodology will be subject to per-flight caps.
- Readiness payment. A one-off payment covering integration of contrail avoidance into flight planning or execution systems (including electronic flight bags), program development, and staff training. It is paid once Contrails.org confirms that integration and training are complete.
- ANSP costs. Co-funding of technical integration and staffing costs specific to ANSP-led trials.
Contrails.org provides trial design, verification, and analysis at no cost to participants. Where a trial needs outside scientific or operational support, Contrails.org contracts for it directly.
Contrails.org contracts directly with each organization it pays. Each contract sets a maximum number of paid flights, a total payment ceiling, and a final date for submitting flight data. Flight payments are made quarterly in arrears for flights that have been flown, verified, and supported by the required data. Payments stop once the ceiling is reached, and nothing is payable for data submitted after the final date.
7. Evaluation Criteria
Proposals will be evaluated on a rolling basis as they are received, using the following criteria:
- Learning value: Contribution to scientific and operational understanding across the trial priorities above.
- Scale: Number of verified avoidance flights, new operators and integrations brought into contrail avoidance, and estimated avoided warming.
- Feasibility and team: Operational readiness and team experience.
- Cost-effectiveness: Expected cost per avoidance flight and per tonne of CO₂e avoided, as estimated by Contrails.org.
- Data openness: Data offered beyond the minimum requirements in Data Terms.
Contrails.org is not obliged to fund any proposal and may fund part of one.
8. Public Communications
Contrails.org encourages participants to communicate publicly about their trial. Participants will share written public communications about the trial with Contrails.org 14 days before release and may not describe results as verified or endorsed by Contrails.org without its written consent.
9. How to Apply
Send proposals and questions to [email protected].