Two experimental studies were performed to determine the value of several types of automation for time-pressured replanning tasks. Subjects modified waypoints of twodimensional routes on a computer screen in response to a sudden change in the displayed environment while having access to one of four levels of automation. In addition to a baseline case with no automation, subjects were assisted with automation that either reduced hazard exposure, ensured meeting time-to-target and fuel constraints, or combined hazard avoidance with meeting time and fuel constraints. Time pressure was imposed by requiring a replan of the route within four different levels of time. The two studies examined different ranges of time pressure, ranging from four levels between 20 and 55 seconds or four levels between 20 and 125 seconds. Results show that the presence of automation was most beneficial in the most time-pressured cases, and that the value of automation decreased as more time was available to the subject. Mid-level automation resulted in more routing errors than either full or no automation cases. Subjects were reticent to deviate from highly automated route suggestions even when significant improvements were still possible.