The Bureau of Mines is seeking to increase safety and efficiency in U.S. coal mines. A multifaceted project is utilizing robotics and automation technologies to develop equipment and techniques for improving mine safety and productivity. One area of research is the technology for automation of a continuous mining machine. This paper focuses on the Bureau's work on one subsystem for a navigation- positioning system. This subsystem is responsible for determining machine heading. An onboard heading system for a mining machine is under development. This multisensor system determines machine heading, pitch, and roll. A directional gyroscope provides heading (yaw), fluxgate sensors provide a compass heading, and gravity- referenced clinometers give machine tilt and roll information. The onboard system utilizes a dedicated microcontroller networked to an external system of computers. Tramming commands, supplied to the network from external computers, are executed by the onboard system. Sensor feedback is employed for closed-loop control of tramming. Further detail is given concerning the operating limitations and error sources of the gyroscope, fluxgate sensors, and clinometers. Actual test results with the mining machine are used to exhibit the various sensor shortcomings. Methods under investigation to limit and circumvent these sensor problems are also discussed.