In short: Each flight is a single line; the top is midnight, moving downwards through the day, and left to right indicates the week of the year, 1987-2007. The colors show delays and whether it was left late or arrived late.
Description: This stacked image shows the number of planes in flight at any one time (summed weekly) from 1987 to 2007, color-weighted for the delays in the flight (blue and red for arrival and departure). Purely green would signify that these planes, on average, suffered minimal delay. When compared to the previous study of this data, much more structure appears. The different hues to the non-green regions indicate whether the departure or arrival was delayed, the slightly orange areas show that though the departure might have been delayed the time was made up during the flight. This occurs in the late 80’s and mid 90’s, but not in recent times.
Point of interest: In such a busy airspace delays are inevitable; however there are a handful of weeks when it worked almost perfectly, usually in 2-3 week blocks. In the last 20 years, there were about 9 of these 2-3 week blocks of minimal delays.
Technical: All domestic flight data from 1987-2007 available at http://stat-computing.org/dataexpo/2009/. The dimensions of the image are specific to denote a calendar-approach to the image, in so much that each pixel is a minute vertically and week of the year horizontally. Each flight is added to the image as a line from departure time to arrival time, so each flight adds to the image as a vertical line. The color channels denote delays (red: departure, blue: arrival) and total number of flights in the air (green channel). Each channel is equalized.