That portion of the trip actually spent in the air. For billing purposes this definition is generally strict and only applies from moment of liftoff to moment of touchdown. Fractional Aircraft Ownership: Fractional aircraft ownership was created to attract business jet charter clients who are not interested in paying for the expenses of owning an entire aircraft, but would like some ownership interest, control and access to a private business aircraft at reduced hourly rates. Fractional owners pay an acquisition fee (typically 1/16 of the value of the aircraft), a monthly management fee, plus an hourly rate typically equal to the direct operating costs of the aircraft. This is a good alternative to private jet rental for heavy users of business jet charters.