Springing Forward Creates Big Issue for Information Technologies

New Daylight Saving Time means updating systems.

by / February 12, 2007
There is a little-known glitch on the way that could soon confound computer systems across the United States. In 2005 when the Congress passed legislation to lengthen the U.S. observation of Daylight SavingTime (DST), the move was a benign effort to squeeze a little more light out of each of our days. The legislation moved the start of DST forward in 2007 by three weeks -- it will begin this year on March 11, rather than the traditional first Saturday in April. At the close of the season, DST will not end until November 4, a week later than the traditional last Saturday in October.

The problem is that programs like Microsoft Outlook are programmed to make the time switch on the traditional April and October dates. So when the changes are made according to the new DST schedule, programs that depend on a computer's internal clock-calendaring and scheduling applications, for example-won't align with real time.

In addition, many calendaring applications don't simply use the computer clock; they often set their own time flags to facilitate scheduling in multiple time zones. Simply adjusting the computer clock will cause an appointment that was coded for Eastern Standard Time to show up one hour off after the computer clock is updated with the new DST schedule.

If only the computer clock is updated and not the corresponding calendar items, appointments in the changed DST window for this year and future years are all impacted by one hour.

There could also be complications in applications that use time stamped data. Patches should be applied to applications or application environments to make sure that they will correctly handle the new daylight saving time rules.

The Multi-State Information Sharing and Analysis Center (MS-ISAC) released recommendations for dealing with this issue:
  • Identify all time dependent applications.
  • Update and apply all appropriate patches to applicable systems after appropriate testing.
  • Ensure that your users are aware of the change and pay particular attention to calendar entries during the new daylight saving time periods.
  • Validate that all critical systems have the correct time after each rotation of DST to mitigate any possible issues on those hosts.
The DST change is "a big issue for most Windows users" who will have to update their systems, explains Larry Jeannette, enterprise operations supervisor at e.Rebpublic. "Some OSX users may have to update also. At the very least, if your PC isn't updated then it will not automatically adjust itself on the new dates that DST starts and ends, ... items in your calendar will be off during those 'extended' 3 weeks."

The DST issue goes beyond desktop computer systems and extends to things like mobile phones, security systems, and environmental controls. Modern buildings use computerized heating and cooling and access control that are often programmed around typical working hours, for example to unlock entrances, turn on lighting, or adjust heating. Another example might be sophisticated logistics systems that track just-in-time manufacturing processes into a state where parts deliveries may no longer align with workers' scheduled shifts.

Gina M. Scott Writer