Apple offers a deeper dive into Crash Detection
are deployed. Not all of the systems have to collect associated data to trigger the system. For example, if the car’s windows are down, the change in barometric pressure will be too subtle to impact the reading.
The system does, however, need to detect multiple data points at once, so simply dropping the phone in a moving car shouldn't accidentally trigger the feature.“I actually had a rear-end fender bender when I was in New York earlier,” says Drance. “My crash detection did not go off, because it’s just one of those minor things where you just get out of your car and keep going.
Bluetooth and Carplay are also used to determine that you’re in a car, though neither are strictly necessary for the feature. “On top of that, we added a lot of signals,” says Huang. “Whether it’s road noise or engine noise, we can see that. We can see that the Wi-Fi routers that you’re using are changing very rapidly -- faster than if you’re walking or biking and so forth.”