U.S. auto-safety regulators are investigating what is believed to be the first fatal crash involving a Tesla Motors car that was driving itself. Mark Kelly reports. Image: Tesla

US highway safety officials are investigating a second crash of a Tesla car that may have been operating on the vehicle’s pioneering self-drive autopilot technology when the dramatic accident occurred.

A week after a fatal Florida crash came to light involving the luxury electric car’s autopilot hands-free system, the National Highway Traffic Safety Administration (NHTSA) said it was looking at a non-fatal accident that took place on July 1 in Pennsylvania.

The NHTSA is investigating “to determine whether automated functions were in use at the time of the crash,” a spokesman said.

According to the Detroit Free Press, the owner of a Model X, Tesla’s newest, SUV-styled model, told police the car was using autopilot when it crashed and rolled over last week. Both the owner and his son escaped injury, police told the newspaper.

Tesla confirmed it had received an electronic data message from the car “indicating a crash event”, but said that it had not received driving logs that would confirm whether the self-drive system had been in operation.

“As we do with all crash events, we immediately reached out to the customer to confirm they were OK and offer support, but were unable to reach him,” the company said.

“It is not possible to learn more without access to the vehicle’s on-board logs.”

Autopilot can steer the car on highways and brake at dangers its sensors detect. But the Pennsylvania crash added to concerns that the self-drive system is encouraging drivers to take their hands off the wheel for extended periods even though the car cannot sense and avoid all dangers.

In the Florida accident, which occurred on May 7, preliminary reports indicated that a tractor-trailer made a left turn in front of the Tesla from the opposite side of a divided highway. The car failed to stop with the truck in front of it and ran under the trailer, destroying the car and killing the driver, 40-year-old technology enthusiast Joshua Brown.

“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 said in a statement.

While the July 1 accident is the second to officially come under NHTSA investigation over the role of autopilot, The Wall Street Journal said Wednesday that it had found others that appeared to be tied to the technology.

In some, the issue appeared to be that autopilot does not recognise stopped vehicles, the report said.