Aircraft condensation trails, known as contrails, are estimated to contribute around 1–2% of human-induced global warming. While the problem has become increasingly recognized within the aviation sector, many airlines have struggled to translate scientific research into practical action.
A new guide aims to change that.
Blue Lines has just published Contrail Avoidance in Practice: A Playbook for Airlines, a free resource designed to help airlines launch and manage contrail avoidance trials. The guide brings together lessons learned from some of the first airlines to test operational measures aimed at reducing contrail formation.
Contrails form when aircraft fly through cold, humid air. Under certain atmospheric conditions, these trails can persist and spread into thin cirrus clouds that trap heat in the atmosphere. Research suggests that contrails are one of aviation's largest non-CO₂ climate impacts.
Several airlines have already conducted contrail avoidance trials, demonstrating that relatively small adjustments to flight routes or altitudes can reduce the formation of the most climate-warming contrails. However, much of the practical knowledge gained from those trials has remained within individual organizations.
The new playbook seeks to make that knowledge widely available. Based on interviews with airline sustainability leaders, dispatchers, pilots, and consultants, it offers guidance on governance, stakeholder engagement, operational planning, cost management, and performance evaluation.
"For many airlines, the challenge is no longer understanding that contrails matter, but knowing how to act," the authors argue. The playbook is intended to provide a practical starting point for airlines looking to integrate contrail management into their operations.
The guide was developed by Blue Lines with support from Contrails, and based on interviews with airline sustainability leads, dispatchers, pilots, and contrail experts from consulting and technology. It was reviewed by experts from organizations including the International Council on Clean Transportation (ICCT), Transport & Environment (T&E), and Green Transition Denmark. It contains:
- A practical checklist for setting up and running your first contrail avoidance flights — from assigning internal ownership to evaluating results.
- A guide to managing cost and risk, including how to define guardrails that keep trials controlled and costs manageable from day one.
- The case for moving now — and how early operational experience positions airlines ahead of emerging non-CO₂ legislation.
- A six-phase rollout model based on real airline experience, showing how contrail avoidance can grow from a first observation flight to full implementation.
ABOUT BLUE LINES
- Blue Lines was founded on Earth Day 2023 by Danish entrepreneur Joachim Majholm.
- The organization's mission is to accelerate the global adoption of contrail management by helping decision-makers understand both the climate impact of contrails and the operational solutions available to address them.
- As pressure grows on the aviation sector to reduce its climate footprint, the release of a practical implementation guide could help move contrail avoidance from a handful of pilot projects toward broader industry adoption.
