There was a successful rescue near here about 3 months ago where cell phone pings saved a couple of hikers. The article in the local newspaper stated that this technology saves quite a few lives per year.

This Google search shows many examples where a cellphone and or cell ping/triangulation has saved lives.
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Earth and sky, woods and fields, lakes and rivers, the mountain and the sea, are excellent schoolmasters, and teach some of us more than we can ever learn from books.

John Lubbock