Apple Crash Detection Feature is a Life Saving Feature When a severe car crash is detected, your iPhone or Apple Watch sounds an alarm and displays an alert. The device reads an alert in case you are not able to see the screen. If you are able, you can choose to call the emergency services or dismiss the alert. If you are unable to do so, the device will automatically call emergency services after a 20-second delay. Apple's crash detection feature can detect severe car crashes like front-impact, side-impact and rear end collisions and rollovers.