14 C.F.R. § 375.42
Occasional planeload charters may be authorized where, because of their limited nature and extent, special equipment or facilities utilized, or other circumstances pertaining to them, it appears that they are not within the scope of the applicant's normal holding out of transportation services to the general public. Such charters are normally limited to those in which the entire capacity of the aircraft is engaged by a single charterer, and since they are occasional in nature, should not exceed for any one applicant more than six flights during a calendar year. This part does not authorize operations that involve solicitation of the general public such as is usually involved in the transportation of individually-ticketed passengers or individually-waybilled cargo, or in which the charterer is a travel agent, a charter operator, a broker, an air freight forwarder or any other organization that holds itself out to the general public to provide transportation services. Carriage of cargo for the operator's own account is governed by the provisions of this section if the cargo is to be resold or otherwise used in the furtherance of a business other than the business of providing carriage by aircraft.
14 C.F.R. §375.42