I just returned from 2 weeks in Japan, live in Las Vegas but my flight connections was in Montreal, The whole trip I kept my phone on with the exception of turning off Data while I was on a cruise ship in Japan, the phone changed to the correct time, I used my Verizon International plan that charged me $10.00 per day, with our connection through Montreal last night I did not want to pay the International plan of the $5.00 per day for an hour in Montreal so had turned it on Airplane mode when we boarded our flight at Narita. My watch did not update when I logged into the free wifi in the Montreal airport even though my phone time did (while on airplane mode). The watch does not update unless you have it off airplane mode but it will if it is not on airplane mode and data is turned off. Hopefully that makes sense.