UNMANNED AERIAL VEHICLE DELIVERY SYSTEMS

Certain embodiments of the present application relate to a method for releasing a parcel from an unmanned aerial vehicle (UAV). The parcel is engaged with a hook attached to a line suspended from the UAV. The method includes lowering the hook such that the parcel is at least partially supported by a target surface, thereby performing an attempt to release the parcel from the hook, performing at least one iteration of an iterative procedure. The iterative procedure includes raising the hook, and determining whether the line remains loaded. The iterative procedure further includes lowering the hook an additional time in response to a determination that the line remains loaded, thereby performing an additional attempt to release the parcel from the hook. The iterative procedure further includes performing an additional iteration of the iterative procedure in response to the number of attempts failing to satisfy a threshold number of attempts.