Here is a reprint of Rick Zurawski's Timezones Explained Article :
INTRODUCTION:
I have had a few questions lately regarding the Time Zone functions/settings of our program. Setting time zones up correctly can be a fairly simple task, but setting them up incorrectly will create a host of problems that will yield less than desirable results. It is very important to set up the different time zone functions correctly so that the many different internal calculations of our program will function correctly, enabling a more accurate 'picture' of each situation unique to different pilot groups. Therefore I will attempt to “break it down” for you. The following is a discussion of the different time zone settings and functions. The discussion is broken down into two sections, Time Zone Settings Explained and Examples. At the end of the initial discussion section, you will find specific examples that should help you apply these settings more accurately to your specific situation. I hope you find it useful.
Time Zone Settings Explained
Daylight Saving Time begins for most of the United States at 2 a.m. on the first Sunday of April. Time reverts to standard time at 2 a.m. on the last Sunday of October. In the U.S., each time zone switches at a different time. In the European Union, Summer Time begins and ends at 1 am Universal Time (Greenwich Mean Time). It starts the last Sunday in March, and ends the last Sunday in October. In the EU, all time zones change at the same moment.
I have included this chart to help you figure out when DST Begins and ends:
United States
DST Begins
At 2:00 a.m. Local:
2003 April 6
2004 April 4
2005 April 3
2006 April 2
2007 April 1
DST Ends
At 2:00 a.m. Local:
2003 October 26
2004 October 31
2005 October 30
2006 October 29
2007 October 28
European Union
Summertime Period Begins
At 1:00 a.m. UT:
2003 March 30
2004 March 28
2005 March 27
2006 March 26
2007 March 25
Summertime Period Ends
At 1:00 a.m. UT:
2003 October 26
2004 October 31
2005 October 30
2006 October 29
2007 October 28
Sounds complex huh? It is. That is why our program has been designed so that once set up correctly, you will only have to make one (1) change to one (1) setting at the start and end of daylight savings time. That’s it! All you have to do is ensure that the initial time zone settings are correct. They will only have to be set up once, and never again. Our program will do the rest.
PREFERENCES:
It is important to set up your user defined preferences correctly. These preferences are the settings that control look and feel of the program, as well as how it performs a myriad of internal calculations. These preferences are found by tapping on (Options)(Preferences). I will walk you through all of them that have an effect on Time Zones and a few that do not, yet are important.
(Options)(Preferences)(General):
Use Popup Lists? Although this setting will not affect time zone calculations or functions, I recommend setting this to “Yes”. It will make entering information and using the program in general, easier.
Use Datebook? Although this setting will not affect time zone calculations or functions, setting it to yes will enable your individual flights to be viewed in the Datebook program in your Palm device. After you have all of your time zone settings set up correctly, you will be able to view your trips in your Datebook correctly.
Airport Domicile? This setting is very important and must be set correctly. The default airport is LGA. You will need to enter the three letter identifier of your specific domicile airport. This setting is what the program will look at for per-diem, among other calculations.
YTD Starting Hours? Enter the hours you have accumulated since Jan 1 of the current year. Enter the value in aviation (1/10th) time. This allows the program an accurate picture of your cumulative yearly