The driver who died in a Tesla Model S using the car’s semi-autonomous Autopilot system last year spent long periods of time with his hands off the wheel, according to new National Transportation Safety Board reports.

Joshua Brown had Autopilot, Tesla’s driver-assist technology that steers, brakes, and provides emergency crash-avoidance maneuvers, engaged for the 37 minutes immediately before the crash, and his hands were off the wheel for all but 25 seconds of that time, the reports said. Brown received seven visual warnings (a steering wheel symbol lighting up on the dash) and six audible chimes alerting him put his hands on the steering wheel.

“The fact that the driver went so long with his hands off the wheel shouldn’t come as a complete surprise,” said Jake Fisher, director of auto testing for Consumer Reports. “Despite warnings to the contrary, if a car can physically be driven hands-free, it’s inevitable that some drivers will use it that way.”

“The technology is not yet advanced enough to have primary responsibility for control of the car,” Fisher added. “That should continue to remain with the driver.”

Tesla now disables Autopilot if the driver fails to put his hands on the wheel after an alarm sounds three times.

Joshua Brown's Tesla Model S after his fatal crash.
Related Stories

The NTSB’s collection of technical reports, released more than 13 months after the May 7, 2016, crash near Williston, Fla., reveals several new important details about the incident. The NTSB releases its preliminary work in a public docket before issuing a final report, which will include conclusions about the most likely cause of the crash, as well as policy recommendations.

The reports also indicate that Brown didn’t slow down before hitting the side of a trailer being pulled by a semi-tractor and blocking the highway. He was going 74 mph in a 65 mph zone.

An eyewitness said the car drove underneath the trailer with a white dust cloud that looked like an explosion. The Model S kept going across the highway, and continued through a drainage ditch. It hit a utility pole with enough force to break it before coming to a stop in the yard of a nearby residence. The airbags didn’t deploy until after the car passed underneath the truck and hit the utility pole. Brown was wearing his seat belt.

An eyewitness told NTSB investigators that both Brown and the truck driver had ample time and opportunity to see one another and take evasive action to avoid the crash but that neither did so. After the accident the truck driver told the Associated Press that Brown was “playing Harry Potter on the TV screen” at the time of the crash. According to the NTSB report, an eyewitness at the crash scene said he didn’t notice whether any entertainment system was engaged in the Tesla.

Photos from the crash show that the roof of the Model S was sheared off in the collision. The NTSB injury report says Brown died of massive blunt trauma to the head, with open fractures to the skull.

The Tesla car didn’t have an event data recorder; that equipment isn’t required by law. The Model S did have computers that recorded car driving data, including real-world images from a camera used by the driver-assist systems. There were camera images, but they weren’t from the seconds leading up to crash. The safety board relied on data provided by Tesla after it was decoded using proprietary Tesla software.

NTSB spokesman Keith Holloway declined to comment on any of the reports in the public docket. The next phase for the agency will be determining probable cause and possible safety recommendations and issuing a final report, he said. There’s no set timetable for the final report stating an official cause of the crash, but the process typically takes months after the docket is open, Holloway said.

Tesla didn’t respond to an email seeking comment.