Contrails could be reduced by 78% over the course of a year by taking actions such as changing altitude to avoid their formation, according to Ambeo CEO Frank Noppel, who focused on contrail formation as part of his phD at Cranfield University.
However, this would lead to a 1% fuel burn penalty, which would lead to more carbon dioxide being emitted.
So I guess scientists with much bigger brains than mine will need to decide whether the impact of contrails and contrail cirrus on global warming is significant enough to justify burning a bit more fuel to avoid their formation.
Noppel demonstrated his findings at the Royal Aeronautical Society's recent Greening of Aircraft Propulsion conference in London (alright, it wasn't that recent, but I've been on holiday since).
The most effective way of reducing contrails, says Noppel, is to relocate flight corridors to avoid the cooler air that aids the formation of these vapour trails. The second best avoidance technique is to adjust air transport movements on a day to day basis, ie fly 2,000ft higher or 2,000ft lower at a given time to avoid the development of contrails. Aircraft optimisation is listed as the third best option.
Noppel's long-term view is that the reduction of contrails "should not be missed out on".