Uber has been faulted for a fatal accident in Tempe, Arizona, last year involving one of its self-driving vehicles. The National Transportation Safety Board voted 3-0 that the probable cause of the fatal accident was the failure of the back-up safety driver to monitor the vehicle because "she was visually distracted throughout the trip by her personal cell phone.” This prompted the National Transportation Safety Board's request for more safeguard drivers for automated driving systems.