Provided are methods and systems for terrestrial data transmission between aircrafts and external networks connected to gates at airports. This type of data transmission is performed through an electrical power cable that includes multiple conductors interconnecting electrical components of an aircraft and a gate. Each conductor may be used to establish a separate broadband over power line (BPL) communication channel using its own frequency range that does not overlap with frequency ranges of other channels. As such, no radio frequency (RF) shielding is needed in the cable and any standard multi-conductor cable may be used. A channel management unit is used to control allocation of data domains among different communication channels depending on characteristics of the data domains, characteristics of the channels, and other factors. For example, one channel may be designated for secure data transfer of specific data domains, such as aircraft control data.