The idea is to equip the drone with flight controllers that will analyze its fall trajectory. The drone will then self-dismantle mid-air by explosion, calculated based on flight conditions, terrain and other factors. This “direct fragmentation for unmanned vehicles” would ensure that the drone hits the ground (or people) in small pieces that would be much less harmful, if at all, than the whole thing.
The patent doesn’t address what will happen to the package the drone is carrying in this event — perhaps Amazon’s earlier parachute idea would be useful in this case.