Hard to believe but there are absolutely empty planes flying across different destinations with a crew onboard. It seems to be money down the drain and a bad business strategy. But in fact these flights play an important role in the airline’s route map.
Why do some planes fly on regular bases empty? Moreover, there is no way to buy a ticket on it. The thing is that airline companies actually do it to keep the slots. The policy with slots is the following especially in terms of popular airports. For instance, if an airline company flies to Heathrow and there is a week or so pause it may lead to the consequences when its slots are given to another airline company for free.
And the slots cost a small fortune reaching $100 million for a single arrival and departure slots. So, flights may be cancelled due to different reasons, for instance, unrest in countries or something like that. And very often in such situations airlines prefer to keep operating the flight empty instead of giving up a slot. And do it, until a situation improves.
Another reason which can justify the fact that planes sometimes fly empty is that they are used to substitute aircraft which need technical maintaining. Or if there are passengers left somewhere due to the plane technical issues. Thus, an empty plane is sent for them. As a rule companies should act promptly in such situations, so they have no time to start selling tickets.