Investigators have discovered Tesla Model S driver Joshua Brown was speeding before the fateful crash into a lorry and that Autopilot was engaged.
A preliminary review by the National Transportation Safety Board (NTSB) into how the 40-year-old Ohio resident died while at the wheel of the Tesla Model S has revealed the car was 9mph over the speed limit, travelling at 74mph in a 65mph zone.
It found the driver was using the Traffic Aware Cruise Control and Autosteer lane-keep assist safety features, which fall under the Autopilot umbrella and are designed to make the Model S Saloon saloon and Model X SUV safer.
The implications of this are that, while the Model S should have seen the truck and its 53-foot trailer carrying blueberries that was making a left turn across the intersection, Brown had set a higher speed than legally permitted and would have had less time to react.
Tesla has theorised as to why the Model S forward-facing radar and 12 ultrasonic sensors failed to detect the truck. In Tesla’s own blog post on the subject, Musk said: “Neither Autopilot nor the driver noticed the white side of the tractor trailer against a brightly lit sky, so the brake was not applied.”
Tesla founder and CEO Elon Musk was asked on Twitter why the radar failed, too. He replied: “Radar tunes out what looks like an overhead road sign to avoid false braking events.”
The NTSB is yet to blame either the driver or Tesla for the crash, but is looking at the factual data to paint a clearer picture of what happened and said it should have a full report around a year from now.
In the report, the NTSB said of the crash: “After exiting from underneath the semitrailer, the car coasted at a shallow angle off the right side of the roadway, travelled approximately 297 feet, and then collided with a utility pole.”
“The car broke the pole and travelled an additional 50 feet, during which it rotated counterclockwise and came to rest perpendicular to the highway in the front yard of a private residence,” it added.
To say the incident has put a dent in the perceived safety of autonomous safety systems (not just Tesla’s) is an understatement, but Musk argued one crash in 130-million miles of Autopilot use makes its cars statistically safer than the average vehicle in the US, which sees one fatality every 94 million miles.
Some safety experts have called for the Autopilot system to be disabled and cars recalled in light of the accident and have asked why a beta safety product is allowed on the market.
Musk has since explained the ‘beta’ term is there to “decrease complacency and indicate that it will continue to improve'”, adding that it will only be removed when Autopilot is “approximately 10 times safer than the US vehicle average”.
The Tesla Model S scored itself the safest ever crash rating in the US. We have tested Autopilot extensively and found it to be reliable on motorways, but by no means infallible and certainly not so on A and B roads, which it has not been designed for.
As Tesla advises, drivers should still be concentrating on the road ahead at all times as it’s a ‘driving assistant’ – not fully autonomous.