I travel a lot and I’ve noticed my iPhone and Apple Watch update to a new local time even if they are still in flight mode. I assumed the device would need to have flight mode off so it could discover the time over a network. How is this happening?
Apple Watch
While everyone says that Airplane Mode stops all wireless communication to and from the phone, it still doesn't stop location services because it cannot interfere with anything in a plane by trying to find its locating via GPS or GLONASS. In fact, the only way to stop GPS is to completely disable it in settings.
Your iPhone uses this for setting the time zone by default. Don't worry, it doesn't use much battery at all. You can make it so that it does not do this automatically, and specify the time zone manually, by going into Settings, Privacy, Location Services, System Services, and Setting Time Zone. You would then specify your time zone in Settings, General, Date and Time.
While everyone says that Airplane Mode stops all wireless communication to and from the phone, it still doesn't stop location services because it cannot interfere with anything in a plane by trying to find its locating via GPS or GLONASS. In fact, the only way to stop GPS is to completely disable it in settings.
Your iPhone uses this for setting the time zone by default. Don't worry, it doesn't use much battery at all. You can make it so that it does not do this automatically, and specify the time zone manually, by going into Settings, Privacy, Location Services, System Services, and Setting Time Zone. You would then specify your time zone in Settings, General, Date and Time.
Thank you FoxFifth and julieda for the great answers. It doesn't bother me at all in fact it's very useful because sometimes I leave the iPhone in Flight Mode to avoid roaming charges so the fact that the time will change automatically means my morning alarm will still go off at the correct time!
When I change time zones how does my Apple Watch and iPhone know the new time even if they are both still in flight mode?
