Pictures: South Jordan Police Department via AP

Salt Lake City - A Utah driver switched on the Autopilot function of her Tesla Model S and then didn't touch the steering wheel again for 80 seconds before the car slammed into a fire engine that was stopped at a red light last week.

The National Highway Traffic Safety Administration has sent its special crash investigations team to the state, after a summary of data from the car involved in the Friday evening crash was released on Wednesday.

According to the South Jordan Police Department's summary of its technician's findings, the 28-year-old driver had repeatedly enabled and disabled the Autopilot throughout the course of her drive. She took her hands off the wheel more than a dozen times, twice for more than a minute each.

She re-enabled Autopilot 1m22s before the crash, let go of the wheel two seconds later and then didn't touch the wheel again before hitting the truck at 97km/h. She had previously told police she had engaged the system and was looking at her phone to compare route maps when the accident occurred.

The driver, who suffered a broken foot in the accident, has not been identified. She was issued a traffic infraction for failing to keep proper lookout. The driver of the firetruck was checked for whiplash injuries but did not go to the hospital.

'Autopilot doesn't make the car impervious to all accidents'

Tesla said on Wednesday drivers are repeatedly warned to keep their hands on the wheel and maintain control of their vehicle at all times, while South Jordan police reiterated that drivers of semi-autonomous vehicles must remain alert and in control of the vehicle at all times.

Tesla's Autopilot relies on a system of radar, cameras with 360-degree visibility and sensors to detect nearby objects and perform basic functions such as parking, steering and emergency braking, which Tesla advertises as being able to "detect objects and automatically apply brakes to help avoid or lessen impact".

Tesla says the system is not designed to avoid a collision and warns drivers not to rely on it entirely; it's unclear if the system activated before this crash. According to the summary released by police, the driver pressed on the brake herself "fractions of a second prior to the crash" and the car had not slowed down from the speed she had set for cruise control.

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The Utah crash is the latest involving an autonomous or semi-autonomous vehicle that has prompted scrutiny from federal regulators. The NHTSA and the National Transportation Safety Board are investigating a March crash involving a Tesla Model X in California where the driver was killed. The Autopilot system was engaged in that crash. Also in March, an Arizona pedestrian was killed by a self-driving Uber car with a backup driver behind the wheel.

AP