Airlines are burning millions of gallons of fuel flying empty ‘ghost’ planes so they can keep their flight slots during the coronavirus outbreak and avoid paying for plane parking at airports. Slots are extremely precious assets for airlines. With more than 200 of the planet’s busiest hubs operating at full capacity, demand for flights exceeds the availability of runways and space inside the terminals. If you stop using your slot, you will lose it to someone else (use-it-or-lose-it). Airliners are sending empty planes just to use the slots and keep them busy at minimum. EU law states airlines must fly 80% of their flights on a slot in order to safeguard their presence at major hubs for the next season.