Re: how does vista calculate ETA

From: GSV Three Minds in a Can (GSV_at_quik.clara.co.uk)
Date: 07/28/04 

Date: Wed, 28 Jul 2004 22:21:52 +0100

Bitstring <410811cb$0$376$ba620e4c@news.skynet.be>, from the wonderful
person A Devrager <devrager@skynet.be> said
>Last Saturday I was driving home (close to Tournai - Belgium) after a
>paragliding holiday in the Vosges.
>And as I hurt my foot in a stupid accident, I was interested to get home
>asap.
>So I swithched the Vista on and selected Navigation with one of the fields
>set to ETA.
>I was highly astonished to see that this Estimated Time of Arrival was
>sometimes 50% wrong.
>When I am 200 km from home and I drive 100 km/h, ETA should obviously be
>within 2 hours ..... but the Vista told me somethging like 3 hours ????
>I was not allways driving straight in the direction of home ... indeed I did
>not build the french motorways .... Could this course deviation be the
>reason of the miscalculation ???
>can anybody explain ?

There are at least two possible sources of error ..

a) you are not headed in the required direction some of the time (the
Vista is, I believe, only interested in 'distance made good' .. i.e. in
the required direction.) Drive in a circle around your destination, and
your ETA will be 'never'.

b) The Vista is using an averaged speed. Not a problem if you maintain a
constant 100km/h, but if you slow down and accelerate then the answer
obvious bobbles about a bit as the average changes. 

-- 
GSV   Three Minds in a Can
Outgoing Msgs are Turing Tested,and indistinguishable from human typing.

Relevant Pages

  • Re: how does vista calculate ETA
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