Daylight-saving glitch threatens mini-Y2K

updated 1:04 p.m. ET March 9, 2007

Daylight saving time arrives a little earlier — March 11 — and stays a little later — Nov. 4 — this year. And it’s bringing a problem along with it that could affect everything from stock trades to airline schedules to your BlackBerry.

Software created before the law mandating the change passed in 2005 is set to automatically advance its timekeeping by one hour on the first Sunday in April, not the second Sunday in March. Congress decided that more early evening daylight would translate into energy savings.

The result is a glitch reminiscent of the Y2K bug, when cataclysmic crashes were feared if computers interpreted the year 2000 as 1900 and couldn’t reconcile time appearing to move backward. If banks and other institutions aren't properly prepared, automatic stock trades reportedly might happen at the wrong hour, buildings that unlock at a certain time could stay shut, and airline flight schedules could be scrambled.

A different Outlook on life?
And for three weeks this March and April, Microsoft Corp. warns that users of its calendar programs “should view any appointments ... as suspect until they communicate with all meeting invitees.” That's because Outlook may not work the way users expect it to.

The problem won’t show up only in computers. It will affect plenty of non-networked devices that store the time and automatically adjust for daylight saving, like some digital watches and clocks. But in those instances the result will be a nuisance (adjust the time manually, or wait three weeks) rather than something that might throw a wrench in the works.

Cameron Haight, a Gartner Inc. analyst who has studied the potential effects of the daylight-saving bug, said it might force transactions occurring within one hour of midnight to be recorded on the wrong day. Computers might serve up erroneous information about multinational teleconference times and physical-world appointments.

“Organizations could face significant losses if they are not prepared,” the Information Technology Association of America cautioned this week.

Dave Thewlis, who directs CalConnect, a consortium that develops technology standards for calendar and scheduling software, said it is hard to know how widespread the problem will be.

VCRs, other gadgets lack update mechanism
That’s because the world is full of computer systems that have particular methods for accounting for time of day. In many, changing the rules around daylight saving is a snap, but in others, it may be more complex.

“There’s no rule that says you have to represent time in a certain way if you write a program,” Thewlis said. “How complicated it is to implement the change has to do with the original design, where code is located.”

Further confounding matters, there are lots of old computer programs whose original vendors don’t support them anymore, meaning there’s no repair available. Some gadgets, such as VCR clocks, may not have any mechanism to update their software.

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