Rapid hazard avoidance maneuvers will be required for unmanned ground vehicles operating at high speeds in rough changing terrain. Without rapidly decreasing speed in every situation, there is limited time to perform navigation calculations based on detailed vehicle and terrain models. This paper presents a novel method for high speed navigation and hazard avoidance based on the two dimensional “trajectory space,” which is a compact model-based representation of a robot’s dynamic performance limits on natural terrain. Simulation and experimental results on a small high-speed UGV demonstrate the method’s effectivenes.