With fractional jets, customers (referred to as "owners") buy a "share" of an aircraft, rather than an entire aircraft. The price is pro-rated from the market price of a full aircraft. Owners then have guaranteed access (for 50–400 hours annually or a certain number of days of the year, depending on share size) to that plane, or a similar plane in the operators fleet, with as little as four hours' notice. Fractional owners pay a monthly maintenance fee and an "occupied" hourly operating fee. Usually the latter is charged only when an owner or guest is on board, not when the plane is flying to a pick up point, or returning to its home base after completing a flight.