Why empty legs exist
Private jets fly where clients need them, not on schedules. A one way flight from London to Nice leaves the aircraft in Nice, and it must fly back or on to its next client. That repositioning flight is the empty leg.
In Europe they cluster on the busy corridors: London, Paris, Geneva and Milan to the Riviera, Sardinia, Ibiza and the Alps, and back again at the end of each weekend or season.
The rules
The route and the time window are set by the operator's other flight, so flexibility belongs to them, not to you. If the original charter changes or is cancelled, the empty leg can be withdrawn.
The price is usually for the whole aircraft, not per seat. Extra stops or a different destination turn it back into a normal charter.
Where to find them
Operators publish their empty legs on their own sites and to aggregators. Atljet reads the feeds of licensed operators and shows them on one live page with route, aircraft type, seats and time window, and a map of the corridors where they appear most.
Because empty legs sell fast, an alert on your routes is worth more than checking every day.
When an empty leg is the right choice
When your dates are flexible and the route is a common one. For a fixed date and time, a normal charter priced on the aircraft nearest to you is often close in price and far more certain.