Introduction: Opportunities exist for machine control systems that can provide safe navigation during extreme weather, and also provide guidance over dangerous terrain. Global Navigation Satellite System (GNSS)-based machine control systems can record a route and then “play” it back as many times as required. A simple application would be to record the route between Scott Base and McMurdo base. During extreme weather with zero visibility a Hagglund equiped with a GNSS machine-guidance system could simply play back the recorded route and safely complete the journey. Another application would be an autonomous vehicle making its way across the ice checking for crevasses with ground penetrating radar. The autonomous vehicle would send a safe route back for a following vehicle to follow. GNSS position data is used by many people during their daily field operations already in the Antarctic. For most applications the absolute accuracy and repeatability of the data is not critical. In fact, few users question the integrity of the data because 5 to 10 metre accuracy meets their requirements and is good enough. Accuracy and repeatability become more important when the position data is being used for machine-guidance and control. To be useful, machine control requires consistent accuracy of less than +/- 500mm, and +/- 25mm would be ideal. Achieving this level of accuracy in the high latitudes of the Antarctic presents challenges. This project will discuss and evaluate the factors affecting the GNSS accuracy and integrity.