According to the OAG blog, the index is "calculated as the ratio of all possible scheduled international connections that could be made by passengers in a six-hour window to the number of destinations served by the airport." This index number, which for Heathrow is 333, determines that it has the most traffic and variety in locations over any other airport. So, if you're planning on doing some international travel to Europe, the likelihood that you'll have a layover at Heathrow is pretty high.
Heathrow's busiest day from the past year saw more than 66,000 possible international connections between arriving and departing flights. 52% of flights at the airport are operated by British Airways, with the most revenue generated off of the route going to and from John F. Kennedy Airport (JFK) in New York. John Grant, senior analyst at OAG, attributes Heathrow's high numbers to the airport's proximity to key Europe, Middle Eastern and African markets and North America. A characteristic that also correlated with a majority of the top 50 "Megahubs" was having a singular airline operate over 40% (or more) of its flights.
Following Heathrow in the rankings is O'Hare Chicago (ORD), with a CI (connectivity index) of 306 — a jump in the rankings from last year's position.To get a larger sense of OAG's analytics, check out the Megahubs International Index.
