[at-l] FYI from BBC

["David F. Addleton" <dfa@wimlaw.com>]

Monday, August 16, 1999 Published at 11:09 GMT 12:09 UK 


Sci/Tech

Navigation bug fears 



Navigation equipment that uses the Global Positioning System (GPS) could
fail at midnight next Saturday due to a Millennium Bug-type computer
problem. 
		
Barnard Parkinson, Stanford University: "It's a case-by-case basis"		
The pilots of light aircraft and sailing boats are believed to be
particularly at risk of accidents if the equipment fails. 
GPS is a US satellite network which transmits signals to receiving
equipment, allowing users to accurately chart their position. It is very
widely used by millions of private, commercial and military users. 
	
Amateur sailors could be most at risk	
But at midnight next Saturday, the system's time signals will automatically
reset themselves to "week zero". Some receiving systems, particularly older
ones, may believe the date is 6 January, 1980, and fail. In May, a US
inquiry heard that devices over five years old are "probably going to have
a problem". 
The US Department of Defense, which runs the GPS system, warns that a
failing device could present one of the following problems: 
It will be unable to locate satellites, resulting in the receiver not
working 
It will take more time than usual to locate the satellites 
It will appear to be working but display inaccurate positions, times or
dates
Clock problem 
	
Each of the 24 satellites orbits Earth twice a day	
The problem, known as the "end-of-week rollover", comes from the way
satellites keep track of time. 
They count the number of weeks since their launch at the start of 1980, but
only up to a maximum of 1,024 weeks (19 years, eight months). They then
return to week zero. 
Military, space and most commercial systems are thought to be well
prepared. The UK Ministry of Defence has missiles, aeroplanes, ships,
submarines and vehicles all using GPS but say all necessary repairs have
been carried out: "We will not have any problems." 
	
	
	
http://news.bbc.co.uk/hi/english/sci/tech/newsid_421000/421553.stm	
		
However, GPS receivers can now be bought for less than £100 and are
increasingly being used by small businesses and amateur sailors and
walkers. They could be hard hit, as they are less likely to have non-GPS,
back-up systems. 
Flat battery 
	
	
Professor Barnard Parkinson, who helped develop GPS, told the BBC that the
problem had been understood for a long while and it was unlikely that any
commercial flights or sailings would be affected. He thought private users
might have some problems but that these were "akin to having the batteries
run out". 
Conservative Party's transport spokesman, attacked the government for not
making more effort to warn the public. It was a "potentially very
irresponsible attitude", he said. 
The UK's Department of the Environment, Transport and the Regions said GPS
was a US system so if "people choose to buy into it, it is their look-out."


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