There was an interesting thread about air traffic locally on a neighborhood mailing list, and this site http://sjc.webtrak-lochard.com/template/index.html was mentioned. I suspect the site is provided to address noise concerns from San Jose's airport, with a ten minute delay. Presumably the "point of closest approach" function, showing the distance and angle that a plane might have to one's home (or any other random place on the map) will display a point in time that is always in the past.
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