On 2023-12-25 18:05, Jeffrey Walton wrote:
On Mon, Dec 25, 2023 at 8:43 PM Charlie Gibbs <cgi...@surfnaked.ca> wrote:
On Mon Dec 25 12:01:59 2023 "Andrew M.A. Cater" <amaca...@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.
Not to mention time, back in the days when weather data was broadcast
across networks of Baudot Teletypes running at 45 baud.
I don't know if that is still the case.
It is. In fact, even though weather data has evolved somewhat, it is
still in a highly compressed form which, once you learn to read it,
enables you to scan a lot of data very quickly. Here's a copy of
this hour's METARs (weather observations) and TAF (terminal area
forecast) for Vancouver, B.C. Note the Z at the end of many times
(ddhhmmZ), although the Z is omitted if this wouldn't be ambiguous.
METAR CYVR 270300Z 08010KT 20SM SCT140 OVC160 08/05 A2998 RMK AC3AS5 SLP155=
METAR CYVR 270200Z 09007KT 20SM OVC160 08/05 A3000 RMK AC8 SLP161=
METAR CYVR 270100Z CCA 05010G15KT 25SM BKN150 BKN170 09/05 A3002 RMK
AC5AC3 SLP168=
METAR CYVR 270100Z 05010G15KT 25SM BKN150 BKN170 09/05 A3002 RMK AC4AC3
SLP168=
TAF CYVR 270304Z 2703/2806 09008KT P6SM FEW080 OVC160
FM271100 09012G22KT P6SM SCT040 OVC100 TEMPO 2711/2715 P6SM
-SHRA FEW020 BKN040 OVC080
FM271500 09012G22KT P6SM BKN040 OVC120
FM271800 10012G22KT P6SM BKN080 OVC150
FM272200 10012G22KT P6SM -SHRA BKN020 OVC040
FM280400 11015G25KT P6SM FEW040 SCT120 BKN200
RMK NXT FCST BY 270600Z=
--
/~\ Charlie Gibbs | "Some of you may die,
\ / <cgibbs@kltpzyxm.invalid> | but it's a sacrifice
X I'm really at ac.dekanfrus | I'm willing to make."
/ \ if you read it the right way. | -- Lord Farquaad (Shrek)
