Background. On-board computing systems (OCS) play a key role in the functioning of robotic complexes (RC), ensuring the transition from remote control to semi- andhardware and software components. Due to the wide variety of solutions from the hardware, algorithmic, architectural and other aspects, as well as the limited computing resources of the UAV RTK, the choice of a rational composition of functional software during reconfiguration during operation is a non-trivial task. Materials and methods. A method for selecting a rational composition of the functional software of the UAV RTK in extreme conditions is presented, which allows selecting a rational configuration of the system depending on the requirements for solving the assigned tasks based on the current state of the external environment, the internal state of the UAV RTK and the existing limitations. Results and conclusions. The method works on multi-version libraries of functional programs of the UAV RTK. The method uses the solution of the generalized problem of a multiplicative multidimensional knapsack with multichoice and additional constraints. This approach allows taking into account complex dependencies between elements of functional software.