Incentivize sustainable behavior, e.g. a small reward for bringing your own coffee cup. This can also be sold by SAS in the Eurobonus store or in flight.

Require everyone to pre-order meals, snacks and drinks so that the plane can carry just the right amount of food and drinks.

Keep your good clients - minimum 10 years as gold member gives you gold for life. Not necessarily 10 years in a row. Now 18 years with 1 missing in the middle = no go

Mount small blades on the side of the wheels to make them spin by themselves before landing to reduce tyre wear upon contact with tarmac.

Track meal consumption on connecting flights to adjust service timing, avoiding back-to-back meals for better passenger comfort.

Change the paper dispensers in the lavatories, often many tissues come at a time. Get single tissue dispensers. Save paper and avoid overfilled bins that looks untidy.