MIT researchers developed a trajectory planning system called SANDO. It guarantees a UAV’s flight path will avoid collisions in unmapped environments. The system works even with unknown moving obstacles. It only needs to know the top speed obstacles could reach. SANDO builds a time-sensitive safety corridor around possible obstacle movements. It uses a heat-map to guide UAVs away from high-risk areas. The planner optimizes the fastest path within the safe corridor. It recalculates trajectories in real time as the environment changes. Simulations and real-world tests showed SANDO avoided all collisions. The research appears in IEEE Transactions on Robotics.