"In contrast, Tesla says that the vehicle logs show that its adaptive cruise control system is not to blame. Data points to Simpson hitting the brake pedal and deactivating autopilot and traffic aware cruise control, returning the car to manual control instantly. (This has been industry-wide practice for cruise control systems for many years.) Simpson's use of the brake also apparently disengaged the automatic emergency braking system, something that's been standard across Tesla's range since it rolled out firmware version 6.2 last year."
[1] https://arstechnica.com/cars/2016/05/another-driver-says-tes...
> Simpson's use of the brake also apparently disengaged the automatic emergency braking system
I don't think the second statement necessarily implies the first. The automatic braking system may be a secondary system to the autopilot that is also disengaged when the driver is actively using the brake system. Indeed, that is how I would expect it to function, as if the driver is actively dealing with the current condition, it is probably a bad idea to wrest control away from them. For example, how do you propose a driver would expect to stop automatic braking that happens erroneously? A quick press of the brakes or gas would be my initial guess, and what I would first try. Given that an erroneously acting auto-braking system can also cause accidents, rapid disengagement capability is important.
It is entirely another another if automatic braking or other safety features deactivate when I am scrubbing speed by "slamming on the brakes". That seems like a very bad idea. If my foot slips from the brake pedal that's one common scenario where I would indeed like emergency automatic braking.
There may be cases where that rule could be relaxed, and the system could engage, but it would need to be beyond all doubt.