During the flights on RNAV routes the aircraft equipped with the flight and navigation systems not adapted for implementation of the area navigation functions, a problem arises of lack of the adequate information support for the crew. The situational awareness of the crew is improved with Dora-processing on-board equipment providing the crew with the required volume of the navigation parameters. An algorithm is offered for calculation and formation of the navigational flight parameters in the horizontal plane along the RNAV routes, which can be used as augmentation program for the onboard software complex. Calculation of the flight navigation parameters is performed in real time based on the data about the current and next phases of the route trajectory based on the actual flight data. We consider a set of the trajectories of the sites applied to build the circuits and route area navigation. The tra/ectory data settings are contained in the air navigation databases, compiled in accordance with the aviation industry standards. The calculation algorithm allows us to obtain the navigational flight parameters and display them in the same format, as in the next one, and change the operational sequence of the route segments. The calculated parameters can be displayed on the cockpit multifunction displays and, if necessary, generate the control signals and Yagi. The calculation algorithm allows adaptation of the onboard navigation system to the requirements of the area navigation systems.