For the years 2004 to 2015, out of the five causes of flight delays, National Aviation System (NAS refers to a broad set of conditions, such as non-extreme weather conditions, airport operations, heavy traffic volume, and air traffic control) was the number one cause followed by Late Aircraft and Carrier. The remaining two causes of flight delays: Weather and Security were comparatively low in number.

The total number of flights for the years 2004 through 2015 was 49774028. Out of those total flights, 38629977 were on time which is about 77%.