They&#x27;re using OurAirports data, filtered to exclude all but &quot;large&quot; and &quot;medium&quot; airports.  Anything smaller than that includes all sorts of cruft like African bush landing strips, heliports, etc.<p><a href="http:&#x2F;&#x2F;ourairports.com&#x2F;data&#x2F;" rel="nofollow">http:&#x2F;&#x2F;ourairports.com&#x2F;data&#x2F;</a>