In short: Each flight is represented by a point, distance from the center indicating the speed (the further out the faster the speed) and the position around the circle is the time (on a 24 hour clock-face, midnight at the top, 12 noon at the bottom). Color is to show the time of day.
Description: This image is a development of the previous image of cab data. Every domestic flight in 20 years is plotted on this image. Three components stand out: the first are the radial spokes that inadvertently signify the on-the-hour arrivals. It seems unlikely this is real, and probably an artifact in how certain kinds of arrival times are recorded, an interesting human element. Second is the broad dark band around the center of the image which would be populated by the majority of flights going at a standard “speed”. Any flight closer-in than this band will be late and further out considered early, or more likely fast, and interestingly three distinct bands seem to indicate three speeds of journey. The final aspect that provides real texture to the image are the curved lines that become more prominent as the day goes by, some of which seem to defy the patterns of the data surrounding them. These appear almost like brush strokes and give the image the impression it was painted or drawn from the imagination.
Point of interest: When looking at cab data the mechanics of it is very accessible and understandable, however with this data the underlying organisation of the aviation industry is not so accessible to people not in the trade. There are interesting smudges of data that seem to defy the “rules” the rest of the data seem to describe.
Technical: All domestic flight data from 1987-2007 available at http://stat-computing.org/dataexpo/2009/. Each flight is a point plotted radially. The distance from the center relates to the “speed” of the flight (calculated as the distance between airports divided by the time it took, including delays). The angle being a 24hr clock-face of arrival time. The color is added as an indication of time-of-day only. The summation is weighted for distance from the center, also to provide an unbiased distribution of points.