> The vehicle was factory equipped with several advanced driver assistance functions by Volvo Cars, the original manufacturer. The systems included a collision avoidance function with automatic emergency braking, known as City Safety, as well as functions for detecting driver alertness and road sign information. All these Volvo functions are disabled when the test vehicle is operated in computer control but are operational when the vehicle is operated in manual control.
However, that appears to be separate from emergency braking under Uber's self-driving system:
> At 1.3 seconds before impact, the self-driving system determined that an emergency braking maneuver was needed to mitigate a collision (see figure 2).[2] According to Uber, emergency braking maneuvers are not enabled while the vehicle is under computer control, to reduce the potential for erratic vehicle behavior. The vehicle operator is relied on to intervene and take action. The system is not designed to alert the operator.
> [2]: In Uber’s self-driving system, an emergency brake maneuver refers to a deceleration greater than 6.5 meters per second squared (m/s^2).
It sounds like Uber didn't trust their own self-driving system enough to allow it to initiate sudden crash stops. Too many false positives, I guess? Of course, simply disabling the function leads to other obvious problems, as shown.