A test vehicle for Cruise Automation, a California startup that wants to build an autonomous driving "kit" that can be installed on existing cars, was involved in a minor car accident in San Francisco earlier this month.

It's not entirely clear if it was caused by a malfunction of the self-driving system or driver error, but it seems likely that the accident isn't one that would occur in a production-quality autonomous car. It happened just after an emergency takeover of control of the vehicle by the test pilot, which may not always be possible in a fully autonomous production vehicle.

According to the accident report filed by Cruise Automation with the California DMV, one of the company's Nissan Leaf autonomous vehicles was traveling in the right lane of 7th Street in San Francisco at 20 mph. The vehicle began moving within its lane to the left, then began correcting to the right. At that point, the driver took manual control of the vehicle, failed to alter the path of the car, and collided with a Toyota Prius (of course it was a Prius) that was parallel parked at the side of the street.

It would appear that it was straight human error. Kyle Vogt, CEO of Cruise Automation, told IDG News that the driver had "enough time" to correct the path of the vehicle to avoid the accident, but "unfortunately made a mistake."

It's ironic that low-speed, non-injury accidents are one of the things autonomous cars should be good at avoiding, and a driver taking over from an autonomous vehicle fails to avoid the accident. Even current production vehicles, equipped with things like lane departure prevention and front collision autobraking, might have been able to avoid the crash.

We don't know whether the car, if left in autonomous mode, would have still crashed, though we've reached out to Cruise Automation to find out. It's possible that production level autonomous cars wouldn't allow the transfer of control from autopilot to manual in such a situation to avoid this exact sort of crash — and that there shouldn't be any sort of opportunity for human error in a handoff.

Either way, this is more of a learning experience for Cruise's R&D department (as well as a bit of an embarrassment) than anything else. Luckily, there were no injuries and only minor damage.