Thirty-one days, three airports

Thirty-one days, three airports

Question. Were January's bad days bad everywhere, or one airport at a time?

• Encoding. One row per airport, one cell per day, colored by that day's mean departure delay. The color ramp is warm and sequential, so dark always means later.
• Why this form. Three lines on one chart would cross and tangle. Strips put the days in the same columns, so a bad day reads as a dark column across all three rows.

What this design gives up

A mean per day hides how many flights that day carried and how spread out their delays were. The first notebook in the series shows the spread.