Incredible. Even for stationary computers like the one I am using now, all time and date calculations are done in Universal Coordinated Time. Any stored time stamps are in UTC. Conversion to local time is ONLY done at the very last for display. That way you don't get your time stamps out of order when daylight time ends in the fall, or you set your laptop to a different time zone. Your program is much simpler when you have a consistent frame of reference for everything.
Exercise: Look at the filetimes in any folder on your computer. Change your time zone. Look at those filetimes again. They're all displayed in the new local time. No fuss. Change your time zone back again. Same thing.
A nav system has to use a consistent time base internally. You can fly over the date line, over the poles, or over the date line near a pole, crossing ten time zones in a minute, turn around and cross directly over the pole and it just doesn't matter to your algorithm. Any other way is a big mess.
Yeah, I think you're right c-five - it's likely that the problem wasn't crossing the date line, but rather going from -180 to +180, the explanation having been mangled by a reporter who didn't know the difference between 180 degrees longitude and the international date line.