Taking a trip and curious how to set your iPhone, iPod touch, or iPad
The calendar app for iPhone, iPad, and iPod touch allows you to change the time zone for any event or meeting with just a few taps. Instead of trying to add and subtract time from your own time zone, just set those specific events or meetings for the time zone they're going to occur in.
Calendar will use whatever time zone your clock settings are set to by default. While this is fine in most scenarios, you also have the option of setting time zones on individual entries.