A system onboard a vehicle may include a vehicle management system (VMS) and a mission management system (MMS). The VMS may include a plurality of VMS nodes for controlling operation of the vehicle. The MMS may include a plurality of MMS nodes for controlling equipment associated with a mission of the vehicle. The system may also include a flexible deterministic communications network. The flexible deterministic communication network may be configurable for communications between each of the VMS nodes, between each of the MMS nodes and between the VMS nodes and the MMS nodes. The VMS nodes communicate using static, deterministic messages and the MMS nodes communicate using dynamic, non-deterministic messages.