The self driving Uber that killed a pedestrian in Arizona in March while its human minder watched a show on her cellphone is not an anomaly. The car’s autopilot needs an alert human driver behind the wheel too, but the driver can become too distracted to take over quickly if necessary.

Tests of unalerted drivers showed an estimated 2.5 sec in perceptual reaction time needed for eye and brain to process the visual scene, make a decision, and send signals to press the brake, though this has varied in other conditions (Taoka, 1989). The delay can be much worse if the human back-up driver is distracted, feels fatigued, and is unprepared to act.

But that’s before an additional delay, sometimes estimated as about 6 seconds for a car traveling at 60 mph in road tests under good conditions for the car to stop, during which it can move about the length of a football field. In addition, the obstacle in braking tests was a stopped vehicle. A person or bike crossing the street could be harder to detect, making the situation even more dangerous.

After driving several Tesla vehicles on Autopilot, and informally testing its operation, Matthew Debord writes in The Business Insider that “drivers should never take their hands off the steering wheel...Tesla asserts that Autopilot reduces fatalities from potential crashes, but for now, allowing the vehicles to operate in a hands-free mode is too dangerous.” .....In previous fatal crashes while Autopilot was engaged, “vehicle logs revealed that the drivers in both cases did not respond to vehicle warnings to retake control before the accidents.”

A Tesla update emitted a warning after 30 seconds of hands off the wheel, according to Ronan Glon writing in DigitalTrends on June 14, but that delay seems much too long. A design that keeps the human in the loop with the help of sensors in the steering wheel and elsewhere coupled with a more immediate warning may not entirely prevent serious errors but would still make the driving safer.

The hazards of self-driving cars are only one speed-bump in the rush for robotic devices with or AI. GPS directions help navigate to an unfamiliar destination, but can also lead to a maze of narrow streets or a backed-up interstate highway.

The takeaway message is to be aware of AI over-reach. For tasks like driving, I think human controllers should be in the loop and prepared to take over immediately when needed.