Timezone Changes

In October 2023, two weeks before daylight savings time (“summer time”) was set to end, Israel briefly considered delaying this. That would’ve been a terrible idea, even if it weren’t at war at the time.

A hacked toll tunnel?

Through the northern city of Haifa, the Carmel Tunnels are a toll bypass of the city. About 10 years ago, on September 8-9, 2013 (yes that date will be relevant), the tunnels were shut down due to a “cyber attack”; rumor is that the toll system didn’t function, and rather than take the loss, the tunnels stayed closed for many hours, causing traffic chaos.

I don’t think it was a cyber attack.

Timezones in Israel

Timezone legislation in Israel is complicated (this sometimes saves lives). Between 2005 and 2012, DST was set to end on the Last Sunday before the 10th of Tishrei. Tishrei is a month in the traditional Jewish calendar, which is less common in day-to-day use in Israel, but does determine holidays (similar to Easter). However, legislation managed to change - twice - between 2012 and 2013. The first change (November 2012) had DST ending on the first Sunday after October 1st, and the second (2013) had DST ending on the last Sunday of October.


Until 2013, the Israeli law for daylight savings time relied on the lunar calendar, so the rule couldn’t be represented easily using the Gregorian calendar. If you look at the timezone database source data, you can see things suddenly got very efficient:

# Rule> NAME>   FROM>   TO>     ->      IN>     ON>     AT>     SAVE>   LETTER/S
# ...explicit lines for every year since 1940...
Rule>   Zion>   2010>   only>   ->      Sep>    12>     2:00>   0>      S
Rule>   Zion>   2011>   only>   ->      Oct>     2>     2:00>   0>      S
Rule>   Zion>   2012>   only>   ->      Sep>    23>     2:00>   0>      S
Rule>   Zion>   2013>   max>    ->      Mar>    Fri>=23>2:00>   1:00>   D
Rule>   Zion>   2013>   max>    ->      Oct>    lastSun>2:00>   0>      S
# ...and that's it.

Anyway, if one were to go by the pre-2012 law but apply it 2013, daylight savings time should have ended on - you guessed it - September 8th. So, in my opinion, a much likelier scenario than a “cyber attack” is simply that some of the systems suddenly found themselves one hour out of sync with the rest, and things got pretty confused. Wikipedia notes that, on this day (as well as October 6th, due to the 2012 law), many smartphones showed an incorrect time because they hadn’t been updated with the latest legislation. And that’s despite having, for September 8th, almost a year’s notice; expecting everyone’s personal devices to be updated in two weeks is pure fantasy.

Nobody’s up changing the clocks at 2AM

It’s important to understand that this is how it all works; computer-based systems have a file somewhere that says “this is when the daylight savings change will happen”, and things happen automatically on that basis; they have to, for a simultaneous transition of all computing systems. Any change to that timezone file takes time and effort to create, test, and distribute, for each different type of computing system. This is not something to be done under time pressure as a “would-be-nice”1. Not unless you want to have “cyber attacks”.

  1. Many years ago, I described an effort to coerce the timezone system into a “change on demand” mode; see post Timezones are fickle↩︎