Dedicated recycling bins in galley/ head for passengers to use during non-service times

Only fly when tailwind

Instead of serving main meals on the flight briefly after takeoff, service the meal in the boarding area. Save load, effort and waste.

Use powder soap instead of liquid soap in all lavatories, powder soap is much lighter thus reducing wieght.

Use travellers feces from flights as a bioproduct. As fuel or to something else useful.

Taxiing from and to gates from runways should be more smooth and with less fuel - using for example AI