Mapping Airways: The World's Flight Paths and Airports
FlightMapper.io - Create digital flight maps
Airline Route Mapper
Open-source airline route maps from 1999 and 2018 created using Python and BTS data (see corresponding comment for clarifications + GitHub link) [OC] : r/dataisbeautiful
Flight routes map - amCharts
Designing the Sky: How Airline Route Maps Changed the Way We Travel - The Statesider
How To Make Flight Maps - One Mile at a Time
Direct Flights - International Flight Directory - Made with React.js