The investigation is the latest to shine a spotlight into potential flaws in emerging autonomous driving technology. The NTSB found last month that one of ride-hailing giant Uber's driverless cars misidentified a pedestrian before it hit and killed her in Tempe, Ariz., in March. Notably, the data from the crashed vehicle shows that the driver had his hands on the wheel three times in the 60 seconds leading up to the crash, but for the last six seconds, his hands were not on the wheel.
But the report does not draw an explicit conclusion about the cause of the crash.
The report said that the Tesla did not try to brake or steer away from the highway barrier.
"Tesla Autopilot does not prevent all accidents - such a standard would be impossible - but it makes them much less likely to occur", the company wrote in the post.
The Autopilot system was engaged on four separate occasions during the 32-minute trip, including a continuous operation for the last 18 minutes 55 seconds prior to the crash.
The NTSB report relays a number of details regarding the events leading up to the crash. A second later, the SUV began a "left steering movement" while still following the other vehicle. "The focus is on what led to this crash and how do we prevent it from happening again". The severed Model X then struck a 2010 Mazda 3 and a 2017 Audi A4. With no vehicle in front of it, the Model X began accelerating again to the 75 miles per hour cruise setting, before colliding with the concrete barrier that separated the highway from the exit ramp at 70.8 miles per hour.
Tesla said earlier that "the reason this crash was so severe is because the crash attenuator, a highway safety barrier which is created to reduce the impact into a concrete lane divider, had been crushed in a prior accident without being replaced". The attenuator had been damaged 11 days earlier in a previous accident and hadn't been repaired, according to NTSB. The barrier is in the median of the highway where it splits into two different directions. Three seconds before the crash, the Model X sped up from 62 to 70.8 miles per hour before hitting the barrier at roughly 71 miles per hour. While the report does not make a ruling on the primary cause of the crash, it does offer a breakdown of everything that happened in the lead-up to the collision, which claimed the life of Walter Huang. The impact was so violent it tore off the front section of the vehicle. Autopilot uses sensors to determine when there is a auto in the lane ahead and adjusts the set speed lower. Back in April, the NTSB announced that Tesla had been taken off of the investigation for releasing information before it could be vetted and confirmed.
When TechCrunch asked Tesla to comment on the matter, a spokesperson declined to do so.
The NTSB said on March 27 that two officials would conduct a field investigation into the incident.