Establish additional partnerships with other airlines on specific routes to, for example, consolidate two half-full flights into one fully-booked flight.

Give/sell digital bag tags to frequent flyers

In Plus and Business on long haul - hand out amenity kits by request instead of placing them on all seats.

Higher prices to reduce number of flights

Charging mobile phones or other equipment from sunlight in the sky. «Day flights are always sunny»

Offer pre-filled reusable water bottles and collect them in before landing