In some examples, a system for transmitting a location of an ownship vehicle is configured to be mounted on the ownship vehicle and includes a positioning system configured to receive positioning signals. In some examples, the system also includes a cellular transceiver, a surveillance transceiver, and processing circuitry configured to determine a position of the ownship vehicle based on the positioning signals. In some examples, the processing circuitry is further configured to determine that the ownship vehicle is located in an identified risk volume based on the position of the ownship vehicle and to cause the surveillance transceiver and the cellular transceiver to simultaneously transmit surveillance signals and cellular signals indicating the position of the ownship vehicle in response to determining that the ownship vehicle is located in the identified risk volume.