with summer holidays around the corner, here is a globe-trotting fact for you. air travel worldwide is set to double to 7.8 billion passengers annually in the next two decades, according to the international air transport association. it brings me to my question. what was the busiest international air route by number of flights over the past year? kuala lumpur to singapore, beijing to kuala lumpur, new york to london or london to map ma mai maine. he intelligently sketches out the problem and possible paths forward. the answer to the gps challenge