WASHINGTON (AP) — The National Transportation Safety Board says the driver of a Tesla SUV who died in a Silicon Valley crash two years ago was playing a videogame on his smartphone at the time.

Chairman Robert Sumwalt said at the start of a hearing Tuesday that partially automated driving systems like Tesla’s Autopilot cannot drive themselves. Yet he says drivers continue to use them without paying attention. He says the board made recommendations to six automobile makers in 2017 to stop the problem and only Tesla TSLA, +4.42% has failed to respond.

“If you own a car with partial automation, you do not own a self-driving car,” Sumwalt said in opening statements. “This means that when driving in the supposed ‘self-driving’ mode, you can’t read a book, you can’t watch a movie or TV show, you can’t text and you can’t play video games.”

The board will determine a cause of the crash at the hearing and make recommendations to prevent it from happening again. Sumwalt says government regulators have ignored the board’s previous recommendations for measures to prevent these crashes.

The March 2018 crash involving a Tesla Model X SUV killed Apple AAPL, -3.17% engineer Walter Huang when it swerved and slammed into a concrete barrier dividing freeway and exit lanes.

Just before the crash, the Tesla steered to the left into a paved area between the freeway travel lanes and an exit ramp, the NTSB said. It crashed into the end of the concrete barrier. The car’s forward collision didn’t alert Huang, and its automatic emergency braking did not activate, the NTSB said.

Huang did not brake, and there was no steering movement detected to avoid the crash, the board’s staff said.

NTSB investigators previously found that Tesla’s system became confused at a freeway exit and was a factor in the crash. Documents released earlier this month quoted Huang’s relatives as saying Huang had previously complained about Autopilot malfunctioning and swerving in the area near where crash occurred.

Autopilot is designed to keep a vehicle in its lane and keep a safe distance from vehicles in front of it. It also can change lanes with driver approval. Tesla says Autopilot is intended to be used for driver assistance and that drivers must be ready to intervene at all times.

NTSB staff determined that Tesla’s system does not adequately make sure drivers are paying attention and recommended that stronger driver monitoring systems be required.

Teslas can sense a driver applying force to the steering wheel, and if that doesn’t happen, it will issue visual and audio warnings. But monitoring steering wheel torque, “is a poor surrogate measure” of monitoring the driver, Ensar Becic, the NTSB’s human performance and automation highway safety expert told the board.

Sumwalt said the NTSB had called for technology more than nine years ago to disable distracting functions of smartphones while the user is driving, but no action has been taken.

Don Karol, the NTSB’s project manager for highway safety, told the board that the staff is recommending that cellphone companies program phones to automatically lock out distracting functions such as games and phone calls while someone is driving. The staff also recommends that companies enact policies to prevent use of company issued cellphones while workers are driving.

“Lockout mechanisms should be default setting and should automatically lock out distracting functions,” Karol told the board.