In this paper a local trajectory planner is described and applied. This planner works in three dimensional environment populated with static and passive movable obstacles. The main contribution of this paper is a proposed of a new method of autonomous navigation. Novelty of this approach relies on splitting the motion planning problem into two stages: a decision mode and a trace mode. In the decision model, vehicle selects its current direction of motion on the basis of the current value of a performance index. In the trace mode vehicle traces boundary and edges of obstacles using its on-board sensors. Depending on vehicle's environment, the two modes follow one another many times. Another new idea is a negative velocity feedback. The feedback stabilizes velocity of the vehicle around a value considered safe in a given environment. The planner, although autonomous, may be adjusted by higher order system (strategic behavior) by changing its parameters. It is not computationally intensive and therefore can be used in real-time applications.