Have you heard about the fears of a mini-Y2K event when the U.S. goes to daylight savings time (DST) earlier than in past years? The law making this change wasn’t passed until 2005, which means that software created before then could miss the date for advancing the time (making you late for appointments from March 11 to April 1).
When Garmin announced daylight savings time patches this week for the iQue M3, iQue M4 and iQue M5, I began to wonder if many GPS receivers would be affected. The apparent concern with the iQues is that these devices are based on Microsoft’s PocketPC platform.
But it turns out that this issue is not limited to PDA’s. For example, Garmin’s latest firmware release for the nuvi 360 includes the following fix: "Updated the US Daylight Saving Time for 2007". Not all Garmin units have had this change incorporated though, and I recommend that you download and install the most recent update prior to March 11. With Garmin units, you generally have to follow several links for firmware upgrades for your unit, before Garmin lists the improvements for each fix on the final page before the download begins. This is the best way to verify that the fix is included.
I expect that not all units will need or receive upgrades. The newest units probably do not have the problem. With handhelds (and perhaps some older units with more options), you can go in and change to daylight savings time manually. Regardless, I don’t see how this could cause any navigation problems, though your estimated time of arrival could be off by an hour.
One thing for sure — your GPS will not pick up this change from the satellites. The almanac data which includes time is transmitted using Coordinated Universal Time (UTC), and the offset for local time must be set in the receiver’s software.
If any readers can shed more light on the subject, I welcome your comments below. I’m especially interested in learning about how other GPS manufacturers are handling this.