Show HN: FlightConnections - Scheduled Flights from any Airport in the World

Great idea, but the first route I searched which was LONDON City LCY to Athens ATH gave me the option of LCY>LUX>ATH, which is not possible. When I click the button that takes me through to skyscanner to check prices, I’m told there are no direct LUX>ATH flights.

Fantastic site, I've used this for a few years. Almost wrote my own version before I found this.

I've always wondered, where do you get your flight route data from?