[time-nuts] Loran-C & French Clocks

Poul-Henning Kamp phk at phk.freebsd.dk
Tue Mar 17 09:46:04 EDT 2009


In message <C5E4EE4D.6481%James.P.Lux at jpl.nasa.gov>, "Lux, James P" writes:

>On 3/17/09 5:58 AM, "Arnold Tibus" <Arnold.Tibus at gmx.de> wrote:
>
>> Interesting facts:
>> The GPS navigation system has GPS Time as its basis. Galileo
>> will have TAI as its basis. GLONASS has UTC as its basis,
>> Air traffic controllers are using UTC.
>> 
>
>The latter is probably because air traffic control is basically done at a
>resolution of 1 minute [...]

The underlying requirements is 10 seconds, and many ATC installations have
special UTC clocks with five digits because that makes it pretty hard to get
it wrong.

One does pause on seeing a clock with   12:34:5   where the last digit clearly
isn't dead, because there is no space for it :-)

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.




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