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Daylight Saving Time: Cause and Effect


Daylight saving time is fast approaching—this weekend in fact!  This year, in the United States, daylight saving time begins at 2 a.m. on March 9. If you’re like me, the whole clock-changing concept is a love-hate relationship.  I hate losing an hour of beloved sleep when the clock “springs forward,” but I thoroughly enjoy more daylight in the evenings during the spring and summer months. And in case you thought I may have made an error, it is actually correct as daylight saving time, not savings.  But daylight savings time (with an “s”) is often used. So being fairly new to the airline business, curiosity got the best of me.  Does the time change influence Southwest operations? swa_4“While daylight saving time does impact our schedules, it is not in a particularly difficult way,” explains Bill Owen, Senior Business Consultant Network Planning.  “However, you can definitely see the shift on flights to/from Phoenix and Tucson.  During standard time those locations are on Mountain Standard Time, but during daylight saving time they are in the Pacific Time zone.” That’s because not all places in the U.S. observe daylight saving time (see #3 on the list below). Here is a look at some other interesting facts about daylight saving time:
  1. The idea of daylight saving was first proposed in 1895 by English-born New Zealander George Vernon Hudson, but it was first implemented by Germany and Austria-Hungary in April 1916.
  2. Many countries have daylight saving time at various times since 1916, but most countries consistently use it since the energy crises of the 1970s.
  3. As mentioned above, not all places in the United States spring forward the clocks. Hawaii and most of Arizona do not observe daylight saving time.  Nor does Puerto Rico.
  4. Adding daylight to evenings benefits retailing, sports, and other activities that exploit sunlight after working hours,but can cause problems for evening entertainment and other occupations tied to the sun (such as farming) or to darkness (such as firework shows).
  5. Clock shifts are usually scheduled near a weekend midnight to lessen disruption to weekday schedules.
  6. A 2009 U.S. study found that on Mondays after the switch to daylight saving time, workers sleep an average of 40 minutes less, and are injured at work more often and more severely.
  7. Studies on daylight saving time have mixed results when it comes to effects on health.
  8. Not all countries begin and end daylight saving time on the same day. For instance, France, Spain, and the United Kingdom won’t spring forward until March 30.  Since 1996 European Summer Time has been observed from the last Sunday in March to the last Sunday in October.
  9. Daylight saving time is generally not observed near the equator, where sunrise times do not vary enough to justify it.
  10. Only a minority of the world's population uses daylight saving time because Asia and Africa generally do not observe it.
In reference to #8 on the list above, Bill Owen explained how this can make the management of time change a little trickier as we move into the international arena. “The Caribbean islands (other than the Bahamas) do not observe daylight saving time, but Mexico does, and its cutover dates are different than North America.  For example—North America goes from standard to daylight saving time on Sunday, March 9.  However, Mexico—with the exception of the immediate border regions—makes the change on April 5.  And ‘fall back’ times are similarly out-of-sync.” So, remember to “spring forward” on March 9, and “fall back” on November 2, unless, of course, you are traveling outside the United States, visiting Hawaii or Arizona, or live near the equator. Photos by SMF Ramp Agent Marah Harris