A factor in common for my own travel plans to visit every country, and also in the how to get to series, is that some countries have flight connections with lots of other countries while others do not.
I find it useful to have an idea of how well connected by air various countries are, and based on questions I often get I hope others will find it useful too.
Introducing Flight Connectivity Index (FCI)
To get a quick high level view I have calculated a Flight Connectivity Index (FCI) based on airline schedules at 30 June 2009. The FCI value is the number of other countries to which you can fly directly from a given country, based on published schedules of IATA airlines. Domestic flights do not count. To simplify the calculation, countries are defined as members of United Nations, as opposed to using one of the many other country lists available.
As airline schedules change I intend updating the calculation from time to time.
Selected 30 June 2009 FCI results
There are 192 member countries of the United Nations, thus the maximum possible FCI is 191 (because domestic flights do not count). No country has direct flights to all other countries - the highest FCI score is 106 for Germany. Four countries have a zero flight connectivity index - these are the small countries of Andorra, Liechtenstein, Monaco and San Marino. The average across all countries is 23.
The top 10 flight connectivity index values at 30 June 2009 are equal to or greater than 68, and the bottom 10 are equal to or less than 3. There are 57 countries with a FCI of 9 or less, 3 countries with a FCI of 100 or more (Germany, France, UK) and 17 countries with a FCI score of 50 or more.
The countries with the highest and lowest FCI values are shown in the two tables below.
Flight Connectivity Index (FCI) - Top 10
Flight Connectivity Index (FCI) - Bottom 10
Full Flight Connectivity Index
I've posted the full Flight Connectivity Index at 30 June 2009.