A method for operating a passive radio-based locking apparatus of a transportation vehicle wherein the locking apparatus enables at least one access function of the transportation vehicle, wherein the passive radio-based locking apparatus includes a mobile device embodied as a radio key unit and a transceiver at the transportation vehicle, between which at least two electromagnetic radio signals are exchanged for the electromagnetic radio connection, and for the operation, one parameter of each of the radio connections of the passive radio-based locking apparatus is modified. Prior to enabling the access function, an identification feature of at least two data communication interfaces for setting up communication for the radio connections at the radio key unit and/or at the transceiver is modified and also each is set to a latest value, and the access function is enabled only in response to the relevant identification feature having the latest value.