SAN FRANCISCO — Mozilla chief technology officer Raffi Krikorian's Tesla Model X crashed into a wall while in Full Self-Driving mode last year in San Francisco, totaling the vehicle. Krikorian suffered a concussion in the crash, which occurred while he was driving to drop his son off at a Boy Scouts meeting, and no one else was hurt.

Krikorian recounted the incident in an essay published Tuesday. "Something felt off—the steering wheel jerked one way, then the other, and the car decelerated in a way I didn't expect. I turned the wheel to take over," Krikorian wrote. "I don't know exactly what the system was doing, or why. I only know that somewhere in those seconds, we ended up colliding with a wall."

In his essay, Krikorian described the challenge of monitoring semi-autonomous systems. "I was asked to snap from passenger back to pilot in a fraction of a second—to override months of conditioning in the time it takes to blink," he wrote. "A machine that works perfectly needs no oversight. But a machine that works almost perfectly? That's where the danger lies."

From 2015 to 2017, Krikorian led Uber's self-driving division and oversaw testing of a fleet of autonomous vehicles.

Tesla and other manufacturers require drivers to supervise vehicles equipped with Full Self-Driving and be ready to take over at a moment's notice if something goes wrong. Modern driver-assist systems such as Tesla's Full Self-Driving can handle nearly every driving situation.

Tesla faces regulatory investigations over reports that vehicles equipped with Full Self-Driving drove on the wrong side of the road, ran red lights, and attempted to drive through railroad crossings. The company has faced several lawsuits over fatal crashes involving Full Self-Driving and its predecessor Autopilot, including being ordered to pay just over $242 million in damages over a 2019 crash that killed a 22-year-old woman.

In December, a California judge ruled that Tesla's advertising falsely suggested cars equipped with Full Self-Driving and Autopilot could drive themselves.