Discount on available seats if booked 5 hours before departure to fill up empty seats

Using hydrogen tanks in the rear of the plane, for example. This could work on shorter routes such as domestic flights or intra-Europe.

Better food = less food waste. I see a lot of boxes not being emptied. So make sure it's good quality food to most peoples liking. Keep it simple and good

Bio fuel / green fuel as default, and having to pay more as a passenger if you want to fly on fossil based airplane fuel.

Magazines and security and safety papers, is put on the sas app or screen only for long hauls to save paper

Only one checked-in baggage with Plus ticket