https://finance.yahoo.com/news/ntsb-apos-preliminary-report-uber-145216516.html

It makes sense; after all, if the safety features were engaged, that would mean that two separate systems would be competing for control of the Volvo. However, it's surprising that the Uber self-drive system doesn't have its own emergency braking feature. According to the report, the computer recognized that emergency braking was necessary, but couldn't engage the system because it was disabled.

ignore objects in the road that the system determines aren't threats." data-reactid="9">The driver was also not alerted that the self-driving system had detected an object. There wasn't much to be done at the point the system determined emergency braking was necessary, just 1.3 seconds before collision. Human reaction time isn't that swift. But the pedestrian was detected a full six seconds before the crash, yet no alert was provided to the driver. It was first classified as an "unknown object," which may have exacerbated the situation, as the software is designed to ignore objects in the road that the system determines aren't threats.