I adopted to the 24 hour clock when I was an astronomy grad student. When we didn’t have set classes my sleep schedule went totally wacky. 7:00am & 7:00pm look remarkable similar at times of the year, and if you are sleeping in an unfamiliar place and have just put in an 18 - 20 hour day of coding, the only clue you might have as to the actual time is if you have to do math when you look at the clock face.
I also find it helps when setting alarms. Generally I don’t have to set a wake up for 18:00 but it can be easy to miss the dot (and does that mean AM or PM?) or the tiny text and inadvertently mis-set for the wrong half of the day.
At a recent hotel stay I pretty much ignored the hotel alarm clock (I use my iPod for an alarm) but I noticed that it was running about 15 minutes fast. On the third day of my stay I looked closer and it was actually 12h15 fast (or 11h45 slow).
The final reason I do 24 hour time is it is a lot easier to calculate durations across the noon boundary. At a recent job I was working from 7:00am to 5:30pm with an hour lunch break. 17.5 - 7 - 1 = 9.5 is an easier calculation.
Because 6.7 billion people on the planet do it this way. Everyone except Americans. I must be one of the few Americans who has never served in the military and who always uses a 24-hour clock.
I sleep in a *lot *of hotels. I never use their clock but for curiosity I try to note whether it’s set right or not. That’s part of my pre-bed ritual which includes the hard-learned step of checking to see if the alarm was left on by the last guest or maid.
IME about 75% of them are set 10-15 minutes fast. I blame flight attendants. About 15% have the am/pm indicator wrong. 'Merkins be idjits.
The American film industry is another where you’ll sometimes see the 24-hour clock, since film crews operate during both day and night, depending on the needs of the project. A 7:00 “call time” is almost as likely to mean p.m. as a.m.
When you use it frequently, it becomes second nature. I don’t mind it at all.
I live in Israel, and all times are written using 24 hours. All our bedroom clocks display 24 hour time, and all our wall timers have a 24 hour dial. It’s all written; nobody will refer to 3 p.m. as 15:00 when speaking. If someone asks me the time, I won’t answer “5 minutes after 21.”
If you are working 24 hour shift patterns it is quite important to be unambiguously clear, and I imagine that if you live north of the Arctic circle when there is either no day, or no night then it probably is a good idea too
UK person here. Written time is pretty much always 24 hour. Four digits cleanly and clearly convey all the information you need. (With the possible exception of potential ambiguity of 0000).
Have a look at this bus timetable between Edinburgh and Glasgow. Citylink Bus Timetable. Dead simple, and helpfully uses 2359 as a departure time to make it really clear.
24:00 30 Oct is the same moment as 00:00 31 Oct, depending on whether you want to count it as part of the preceding day or the following one. So the 24-hour clock has that one covered, too. The standard American timekeeping fails on that point, but not because of it being 12 hours, but because it doesn’t use zero.
When it comes to dates, I always use the format 30 Oct 2017 (possibly dropping the year, if it’s unambiguous). This has a few advantages. For one, no matter what format my reader is used to, it’s never ambiguous, and they can always see what I mean. For another, the three letters in the middle serve as a separator between the numbers, so there’s no need for hyphens or slashes to separate them (and slashes, in messy handwriting, can be mistaken for ones).
Our scheduling department makes sure that nothing is scheduled to arrive or depart at exactly 0000 local or 0000 UTC. An extra minute or several is added or subtracted as needed. Normally they greatly prefer to set the time at 2359 or earlier unless it will naturally fall after about 0015.
It depends on which standard you use (ref xkcd: Standards) but IMO/IME 2400 is not well-defined in the standards I’ve used. Thoughtful people can decode it correctly, but strictly speaking it’s an invalid time expression.
I also work for the military, and in medicine, so it’s not only habit, it’s expected. I’m working in their world, I have to speak the native language. I don’t do it outside of work, not intentionally at least, to people who are unrelated to either field.
A partial look at something I look at every work day. For me the times are second nature. I don’t have to think about it at all. I would think most business programmers use 24 hr time. I’m sure most science programmers do.
**Name Description Time**
FRIDAY Cust Ship Rpt for QC 05:15
SUNDAY Sunday Post IPL of AS4 05:00
SUNDAY2 Sunday Rebuild Co19 05:10
UNLOAD Unload Tape
0430 Morning Job Stream 04:30
0500WD Morning Jobs Weeks Day 05:00
EOUTQ Clears Outqs for set d 05:20
SIDWNLD IDSI Download from AS4 20:00
0QTYCL Invoices Wth 0 Qty Bil 16:30
AUDIT IT Audit Reports 02:00
AUPDDATE Update LDA's for ROBOT 00:01
MSUPCL Update KC files w/ LIM 10:20
