The recently launched Operation Blue Skies trial is evaluating whether small adjustments to flight paths can reduce the formation of climate-warming contrails. The trial has renewed focus on aviation's broader atmospheric impacts beyond carbon dioxide emissions.
Contrails form when hot, moist exhaust from jet turbine engines mixes with freezing air at high cruising altitudes, typically between 30,000 and 40,000 feet, where temperatures can drop below minus 40 degrees Celsius. The resulting water vapour condenses and freezes into tiny ice crystals behind the aircraft.
When an aircraft travels through cold, ice-supersaturated air, these ice crystals can persist and spread into contrail cirrus clouds, creating a warming effect on the climate. Researchers and airlines are studying flight route adjustments to minimize contrail persistence.
