Re: difference in seconds between two formatted dates ...

[Jeffrey Walton <noloader@gmail.com>]

On Mon, Dec 25, 2023 at 8:43 PM Charlie Gibbs <cgibbs@surfnaked.ca> wrote:
>
> On Mon Dec 25 12:01:59 2023 "Andrew M.A. Cater" <amacater@einval.com> wrote:
>
>  > Yes - that's the obvious way. I set my machines to /etc/UTC (or
>  > /etc/GMT) and leave them there. No daylight saving time, no offsets -
>  > all logs unambiguous. That's why (worldwide) radio logkeeping is/was
>  > in UTC. If you're travelling in an aircraft, you don't _need_ to know
>  > ground time but you do need to know flight time against a reference
>  > time. The Royal Air Force keep to UTC wherever they are in the world
>  > for just this reason.
>
> Not just the RAF.  All aviation works in UTC, to avoid problems when
> flights cross time zone boundaries, and to keep wide-area weather
> forecasts sane.  Your average airline passenger never sees UTC,
> since airlines use it behind the scenes and convert it to local time
> for display purposes.  (That's why you can see some strange intervals
> between departure and arrival times.)

The US airlines I worked for in the late 1980s and 1990s used Zulu
time. If I recall correctly, flight arrivals and departures were
specified like 10:34Z or 23:10Z.

I don't know why Z was used instead of UTC or GMT. Probably to save
space, and save some ink if a schedule was printed.

I don't know if that is still the case.

Jeff