The National Transportation Safety Board is tapping the brakes on autonomous vehicle tests on public roads. On Nov. 19, the agency called on lawmakers to create a review process before allowing automated test vehicles to operate on public roads, based upon the agency’s investigation of a fatal collision between an Uber automated test vehicle and a pedestrian.

During a board meeting held to determine the probable cause of the March 18, 2018, Tempe, Arizona, crash, the NTSB said an Uber Technologies Inc. division’s “inadequate safety culture” contributed to the fatal collision between an Uber automated test vehicle and a pedestrian. The vehicle operator was uninjured in the crash; the pedestrian died.

According to NTSB's review of the accident, Uber’s Advanced Technologies Group modified the 2017 Volvo XC90 with a proprietary, developmental automated driving system. The vehicle’s factory-installed forward-collision warning and automatic emergency braking systems were deactivated during the operation of the automated system. An Uber ATG operator was in the driver’s seat, but the automated system was controlling the vehicle when it struck the pedestrian at 39 mph.

NTSB investigators determined that the immediate cause of the collision was the failure of the Uber ATG operator to closely monitor the road and the operation of the automated driving system, because the operator was visually distracted throughout the trip by a personal cell phone.

Contributing to the crash, the report said, was Uber ATG’s inadequate safety risk assessment procedures, ineffective oversight of the vehicle operators, and a lack of adequate mechanisms for addressing operators’ automation complacency – all consequences of the division’s inadequate safety culture.

“Safety starts at the top,” said NTSB Chairman Robert L. Sumwalt in a release. “The collision was the last link of a long chain of actions and decisions made by an organization that unfortunately did not make safety the top priority.”

The pedestrian’s impairment at the time of the crash, coupled with crossing outside a crosswalk, contributed to the crash, as did the Arizona Department of Transportation’s insufficient oversight of automated vehicle testing, the NTSB found.

Among the investigation’s findings:

• The Uber ATG automated driving system detected the pedestrian 5.6 seconds before impact. Although the system continued to track the pedestrian until the crash, it never accurately identified the object crossing the road as a pedestrian – or predicted its path.

• Had the vehicle operator been attentive, the operator would likely have had enough time to detect and react to the crossing pedestrian to avoid the crash or mitigate the impact.

• While Uber ATG managers had the ability to retroactively monitor the behavior of vehicle operators, they rarely did so. The company’s ineffective oversight was compounded by its decision to remove a second operator from the vehicle during testing of the automated driving system.

• Uber ATG made several changes to address the deficiencies identified, including implementation of a safety management system.

The NTSB issued a total of six recommendations to the National Highway Traffic Safety Administration, the state of Arizona, the American Association of Motor Vehicle Administrators, and Uber ATG. Among them, NTSB recommended that NHTSA require entities wishing to test a developmental automated driving system on public roads to submit safety self-assessment plans before being allowed to begin or continue testing and that NHTSA should review the plans to ensure they include appropriate safeguards.