The National Transportation Safety Board has sharply criticised Tesla’s lack of system safeguards in a fatal 2018 Autopilot crash in California and US regulators’ approach in overseeing the driver assistance systems.

NTSB board members questioned Tesla over the design of its semi-automated driving assistance system and condemned the National Highway Traffic Safety Administration for a “hands-off approach” to regulating the increasingly popular systems.

The board expressed growing frustration with the failure of US regulators to take a more aggressive approach to overseeing driver assistance systems and also faulted Apple Inc and other smartphone makers for refusing to disable devices when users are driving.

The board’s criticism posed a direct challenge to the auto industry’s efforts to profit from partially automated vehicles and the smartphone industry’s quest to keep user eyes on their devices.

The NTSB can only make recommendations, while the NHTSA regulates US vehicles. It has sent teams to investigate 14 Tesla crashes in which Autopilot is suspected of being in use.

The California crash – involving a driver who was playing a game on his phone during the fatal trip – illustrates that “semi-autonomous vehicles can lead drivers to be complacent, highly complacent, about their systems, and it also points out that smartphones manipulating them, can be so addictive, that people aren’t going to put them down,” NTSB Chairman Robert Sumwalt said.

“It’s time to stop enabling drivers in any partially automated vehicle to pretend that they have driverless cars. Because they don’t have driverless cars,” he said.

The NHTSA said it will carefully review the NTSB’s report. The agency added that all commercial motor vehicles “require the human driver to be in control at all times, and all states hold the human driver responsible for vehicle operations.”