Message-Id: <3.0.3.32.19990819130908.03009910@olsusa.com>
Date: Thu, 19 Aug 1999 13:09:08 -0400
To: lancair.list@olsusa.com
From: Marvin Kaye <marvkaye@olsusa.com>
Subject: Beware GPS rollover problem
Mime-Version: 1.0

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Reprinted from this week's AvFlash:

GPS ROLLOVER CAUSES CONCERNS...
Once every 20 years, the GPS software goes through an "End-of-Week"
(EOW) rollover, and at 0000 UTC August 21 -- next Saturday -- the first
rollover hits.  It could cause trouble for some pilots.  On Thursday,
August 19, at 1000 UTC (6 a.m. EDT), new information tables, called
"almanacs," will be uploaded to the GPS satellites.  GPS receivers not
fully compliant with current standards could malfunction because of
those new almanacs.  Several things might happen -- your GPS might not
work because it might not be able to locate the satellites, it may take
more time than usual to locate the satellites, or it may appear to be
working fine, but display inaccurate information.

...BUT WE HAVE ADVICE TO SEE YOU THROUGH
To prevent any problems, simply check with the maker of your GPS prior
to August 19 and ask if your receiver and application are EOW-rollover
compliant.  Be sure you have the receiver model, serial number and
firmware version or release date displayed on the startup screen when
you call.  To get manufacturer contact information, you can call the Y2K
consumer hotline at 1-888-USA-4-Y2K.  If you're using GPS as a sole-
means navigation system this week and you haven't checked with the
manufacturer, just make sure you have some redundant systems in the
cockpit.  Remember, that VOR is be there for a reason.  Let's all be
safe up there.


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