Friday, July 22, 2005

Daylight Saving Time: Computer chaos this fall

Yesterday, the American House and Senate reached an agreement to extend Daylight Saving Time, beginning it three weeks earlier each year, and ending it one week later.

What the authors of this bill fail to realize is how much chaos this will cause for computer systems around the country.

Many computer operating systems like Windows actually base their clocks on Universal Coordinated Time (UTC), also known as Greenwich Mean Time, and the time they display is calculated as an offset from Greenwish Mean Time. For example, here in New York, we are UTC minus 5 hours, and during the months when Daylight Saving Time is in effect, an hour is added, making us UTC minus four hours.

The problem is that most computers today automatically make the switch to and from Daylight Saving Time, and since most North American and European countries make this switch on the same day, this is very strightforward. Now, the US government is throwing a wrench into this whole thing by changing the dates on which Daylight Saving Time kicks in and when it stops.

To accomodate this change, computer operating system manufacturers like Microsoft, Apple, and IBM, the whole Linux community, and network router/switch vendors like Cisco will need to scramble to create software patches that will accomodate this change, so that their respective systems will make the change on the correct date.

What will cause problems is that undoubtedly, some people will fail to apply the patches, and their computer systems will fail to automatically adjust to the time change. And, if these computer systems run time-sensitive applications (financial systems, etc.), this may cause some problems.

It will also throw the United States out of whack with the rest of the world, leaving other countries to decide whether to allow this disjoint to continue, or to join the United States in making this change.

I really do not think the implications of this bill were very well thought through.