The present invention is directed to the remote control of locomotives, and more particularly to various methods and apparatus employed in implementing systems for such remote control. Contemplated in the present invention are systems and methods for not only reliable remote-control communications, but also the use of repeaters and communications servers to assure reliable, centralized communication between locomotives and operator control units. In another embodiment, there is described a reliable distributed communication mode using an uncorrelated time sequence that does not interfere with a time division multiple access network. Differentiation between the centralized mode and the distributed mode is accomplished by assessing whether a locomotive and control unit is within a rail yard's infrastructure. Moreover, reliability is assured using a coordination server that dynamically routes packets between multiple satellite RCL repeaters based on received signal strength. Lastly, the present invention further contemplates the use of an out-of-band transmission to upgrade and test operator control units, thereby allowing for field maintenance and software upgrades.