General Question

gorillapaws's avatar

How is the extra hour documented in the fall daylight saving time change on official stuff?

Asked by gorillapaws (30612points) March 11th, 2023

It is my understanding that in fall the clocks go from 1 to 2 normally and then at 2am they jump back to 1am again. So how does that get documented on official stuff so people understand which of the two 1am – 2am sequences are being described? Is one denoted with a * or something?

E.g. Air traffic control, time of birth/death, train schedules in places where trains run all night, time-based triggers and logs on servers, banking transactions, police reports, etc.

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10 Answers

Response moderated (Unhelpful)
Blackwater_Park's avatar

Most of those things run on a “system time” that coordinates activities regardless of geography.

Tropical_Willie's avatar

Try this:

1:59 daylight saving time and and hour and two minutes later 1:01 standard time!

LuckyGuy's avatar

Someone at NTSB (or some other traffic investigation agency I don’t recall ) noticed that there was one hour in the year that had an extremely low accident rate – virtually zero. While another had twice the average accident rates for the same hours and days of the week. Of course the zero occurred during the magic hour we skip when clocks “spring forward” and the hour with double accidents was the one we repeat when we “fall backward”.
It is recognized and adjusted depending upon the data. Similar situation occurs on leap years when the simple monthlyl data indicates people use 3.6% more fuel in Leap Year February’s.
A “spews” commentator with a deeply furrowed brow can feign outrage by just publishing those numbers out of context. “Ban Leap Years!!! People use 3.6% more fuel in Leap Year Februarys.” “Ban Daylight Savings!!! There are twice as many accidents/births /deaths/ meals eaten during that hour in the Fall.” And people would believe it !

Strauss's avatar

Many years ago I was working at a bar that closed at 2:00 AM on Saturday (I know, technically it was Sunday morning, but it was the Saturday night shift). When the time “fell back” I ceremoniously turned the large clock from 1:59 AM back to 12:59 AM…and the crowd went wild!

Response moderated (Unhelpful)
JLeslie's avatar

I’m pretty sure spring forward is 2am becomes 3am. If I’m wrong it doesn’t affect my explanation below.

Aviation use Zulu time (Z time) also known at Universal Time (UTC). Zulu doesn’t change with the seasons, it’s constant.

The US uses S for standard and D for daylight savings. So, right now most states are in Daylight Savings Time. At 2am EST it switched to 3am EDT, which is also 07:00 Zulu or UTC.

It’s more like clocks go from 1:59 to 3:00. So, a baby would be born at 1:59 EST or 3:00 EDT.

JLeslie's avatar

Train schedules for passengers or a plane ticket will state local time for departures and arrivals. Local at the place of the stop, as it always does.

LostInParadise's avatar

For computer programs that keep track of the duration of certain events, it is best to use Zulu time.

Forever_Free's avatar

Most everything in computing uses UTC and local system time to adjust. We learned all about this with the Y2K potential issue. If it is programed correctly, the only issue is our body adjusting.

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