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.

Add green flights on some departures. nothing is served on these flights, only hand luggage is allowed, but you earn more Eurobonus points if you choose such a departure.

Free reebooking to earlier flight when avilable. Result in filling up seats, and making it more likely to fill up seats on later flights

Let it be easy to take steps when buying bio-fuel.

Use the food leftovers from each flight to make more biofuel

If possible, adjust aircraft speed to reduse fuel consumtion