potential train-handling benefits. Over an undulating track profile, a skillful operator can manipulate the relative power outputs (as well as dynamic- and air-brake applications) to minimize run-in and run-out of coupler slack throughout the train. Reduced draft forces along a train reduce the lateral force between wheel and rail on curves, thus reducing fuel consumption and wear on various running-gear components as well as the potential for a stringline derailment. Another benefit is quicker application of air brakes. With all braking control on a conventional train being established at the head-end, it can take several seconds for brake pipe pressure changes initiated by the operator to propagate along the train. Under radio-controlled DP operation, the brakes are set at remote locomotives almost simultaneously with the command initiated on the lead locomotive, providing a more uniform air brake response throughout the train. The main disadvantage is the operational time needed, and track configuration required, to add and remove additional locomotive units. Secondary disadvantages are the costs associated with equipping locomotives with the extra control apparatus and the potential for the intermittent loss of the telemetry signal. This latter is known as "communication interrupt" and is coped with by fail-safe software program inclusions. Technology Distributed power should not be confused with multiple-unit operation, which is a capability, generally found on all locomotives, that connects multiple locomotives directly together via MU cables and air brake control lines. MU operation in North America is designed so that any two locomotives so equipped, and regardless of age and manufacturer, can be coupled together and operated as a single locomotive by one operator in the cab of the lead unit. This is accomplished via a 27-pin MU cable and the connection of three additional air lines separate from the brake pipe (sometimes also called the "train line"). DP is an entirely separate arrangement to control locomotives that are physically separated from the lead unit(s) and therefore impossible to connect via multiple-uniting. The first locomotive at the head of the train is called the "lead unit", and "remote units" can be located at separate positions throughout the train. Each DP remote unit can be MU-connected to other units at that position to provide one or more "remote consists". The setup and linking of the DP lead and remote units is fairly straightforward, and the air brakes of the remote units also have to be properly configured to