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.

Make the app as lightweight as possible. Remove images, animations and leave only the bare necessities. This saves data transfer and storage - which in turn saves energy.

Use larger packages for the most consumed drinks, instead of handing out endless amounts of cans (less garbage, less weight on board) .

International ban on private jets. Everyone can fly commercial. With option like business and first class this should be achievable if all nations want to reduce emission

Higher prices to reduce number of flights

Ask gold members how much luggage they plan to bring to plan for correct weights. A lot of business travels include 3 checked bags but the majority flies with handluggage