The Apple Watch Series 8, Apple Watch SE (2nd generation), and Apple Watch Ultra use the following sensors to detect severe car crashes:
- Motion sensor with a high dynamic range gyroscope and high-g accelerometer[1][2]
- GPS[1][2]
- Barometer[1]
- Microphone[1][2]
- Advanced motion algorithms[1]
These sensors work together to accurately detect examples of severe crashes that can be detected, such as front-impacts, side-impacts, rear-end collisions, and rollovers[1].
When a severe car crash is detected, the Apple Watch will sound an alarm, tap the user's wrist, and display an alert on the screen[2]. If the user is unresponsive after 20 seconds, the watch will automatically initiate an emergency phone call to share the user's location with emergency services[2][3].
Citations:[1] https://www.youtube.com/watch?v=VPHW6vZ6YDY
[2] https://support.apple.com/en-us/104959
[3] https://support.apple.com/guide/watch/manage-crash-detection-apd3a60b5576/watchos
[4] https://support.apple.com/en-us/108896
[5] https://www.apple.com/newsroom/2024/09/introducing-apple-watch-series-10/
[6] https://www.apple.com/apple-watch-series-10/specs/
[7] https://www.apple.com/eg/apple-watch-series-10/specs/
[8] https://www.apple.com/watch/why-apple-watch/