The US national transportation safety board (NTSB) has released its preliminary report into the fatal Tesla Model X crash in California, highlighting a number of concerning issues.
The report found that the vehicle's autopilot system was engaged on four separate occasions during the 32-minute trip including a continuous operation for the last 18 minutes and 55 seconds prior to the crash.
The NTSB revealed that the vehicle was travelling at approximately 71 miles per hour as it crashed into a previously damaged crash attenuator before colliding with an Audi A4 and Mazda 3.
It also found that the Tesla's speed increased in the three seconds before impact from 62 to 71 miles per hour with no braking or evasive steering detected prior to impact.
The report also showed that the driver's hands were not detected on the steering wheel in the six seconds before the crash.
In the 18 minutes and 55 seconds of autopilot operation prior to impact, the Tesla provided two visual alerts and one auditory alert for the driver to place his hands on the steering wheel.
The alerts were made more than 15 minutes before the crash though Tesla claims that the driver ignored multiple warnings earlier in the 32 minute drive as well.
The vehicle's electric battery was breached during the crash and a post-crash fire ensued. The Mountain View fire department applied about 200 gallons of water and foam to extinguish the fire.
However, the battery reignited five days after the crash in an impound lot and had to be extinguished by the San Mateo fire department.
The investigation of the crash remains ongoing.