An empty leg is a flight an aircraft has to make to or from Costa Rica with no passengers on board, usually to return to its base or to reach its next trip, and operators sometimes sell those flights for less than a standard charter.
There are conditions. An empty leg only exists because of someone else’s trip, so if that trip moves, the empty leg can move or be canceled too. Some aircraft owners do not allow charter passengers on these flights at all, and finding one on your exact route and date can be hard.
A normal one-way charter is usually priced to cover the aircraft getting back to base, which is why it can cost nearly as much as a round trip. With an empty leg, the aircraft is flying anyway, so the operator may only need to recover part of the cost.
Empty legs suit travelers with flexible dates and a one-way trip. If your dates are fixed, a standard charter is the safer choice, and your advisor will tell you which makes more sense for the trip you have in mind. Call 1-888-987-5387 to talk it through.