I imported a csv dump from OpenFlights and I get errors like airport not found (CBL for example) and many "flight not found". The errors are for really old flights, 2006 to 2012.
Maybe old flights should be imported as-is without trying to validate the flight number or airline name (after 13 years it's almost impossible).
Hi Bogdan, sorry for the long time to reply. We've added CBL airport to our database, can you please send this file one more time? You should be able to add a flight. Let me know if you are missing any other airport at email@example.com Nikita