In the process of negotiating the conclusion of freight transaction between the Parties to the contract of carriage by sea, one of the most important issues is the determination of a reasonable and acceptable freight rate for all Parties to the transaction. When negotiating it, the freight broker is obliged to take into account a large number of factors: the duration of the voyage, the cost of fuel, the navigation area, navigation, etc. However, an important aspect is the presence of possible risk situations in the course of the vessel's voyage, such as weather and climate conditions, technical problems with the vessel, inconsistencies in the process of cargo delivery, changes in the cost of the bunker, etc. All these factors determine the need to take into account and, if possible, distribute the degree of influence of risks on the flight efficiency, which confirms the relevance of the subject of this article. The authors of this article propose a calculation formula for such a flight efficiency indicator as a time charter equivalent, taking into account possible deviations of some parameters that were chosen by the authors on the basis of a probabilistic approach. Also, the authors have developed a methodology for determining the required level of increase in the freight rate, which can be applied in practice by freight brokers in the process of negotiating the charter of a vessel to ensure the required level of efficiency, as a kind of "compensation" for the risk.