Tesla in Autopilot mode accelerated for 3.5 seconds before crashing

SALT LAKE CITY — A Tesla that crashed while in Autopilot mode in Utah this month accelerated in the seconds before it smashed into a stopped firetruck, according to a police report obtained by The Associated Press. Two people were injured.

Data from the Model S electric vehicle show it picked up speed for 3.5 seconds before crashing into the firetruck in suburban Salt Lake City, the report said. The driver manually hit the brakes a fraction of a second before impact.

Police suggested that the car was following another vehicle and dropped its speed to 55 mph to match the leading vehicle. They say the leading vehicle then likely changed lanes and the Tesla automatically sped up to its preset speed of 60 mph without noticing the stopped cars ahead.

The police report, which was obtained Thursday through an open records request, provides detail about the vehicle’s actions immediately before the May 11 crash and the driver’s familiarity with its system.

The driver of the vehicle, Heather Lommatzsch, 29, told police she thought the vehicle’s automatic emergency braking system would detect traffic and stop before the car hit another vehicle.

She said she owned the car for two years and used the semi-autonomous Autopilot feature on all kinds of roadways, including the Utah highway where she crashed, according to the report.

Lommatzsch said the car did not provide any audio or visual warnings before the crash. A witness told police she did not see signs the car illuminated its brake lights or swerved to avoid the truck ahead of it.

Lommatzsch did not return a voicemail message on Thursday. A Tesla spokeswoman, Keely Sulprizio, did not immediately respond to an emailed request for comment.