Systems and methods for enhanced subnetwork preference logic are herein provided. In certain implementations, a method for transmitting messages over a datalink communication system includes identifying a location of a first communication unit; and identifying an altitude of the first communication unit. Further, the method includes selecting a sub-network preference for the first communication unit for communicating between the first communication unit and one or more other communication units, wherein the sub-network preference is selected based on the location and the altitude of the first communication unit, wherein the sub-network preference identifies one or more sub-networks in order of preference; and transmitting one or more messages to the one or more other communication units through a sub-network that is a most preferred sub-network as indicated by the selected sub-network preference and available for communications.