There are a limited number of "tracks" that planes follow, but the details vary from day to day due to weather, and wouldn't show up on a aggregate visualizatio

There are a limited number of "tracks" that planes follow, but the details vary from day to day due to weather, and wouldn't show up on a aggregate visualization very well. http://en.wikipedia.org/wiki/North_Atlantic_Tracks http://en.wikipedia.org/wiki/North_Atlantic_Tracks