OpenFlights can import flights from three sources:
TripIt — Connect directly to TripIt.com to import past and future trips, in bulk or individually. Duplicates are detected.
FlightMemory (.html) — FlightMemory does not have an export function, but OpenFlights can 'screen-scrape' its FlightData pages. Log into your FlightMemory account, go to the FlightData page, and select 'Save Web Page' in your browser. Upload the resulting HTML file. Repeat once for each page of data.
Warning: Be sure to set your FlightMemory language to English before saving the pages.
Note: There is no duplicate detection at this time. If you import a FlightMemory file twice, all flights in it will be added twice.
Note: The FlightMemory format changes from time to time. Please report any bugs or oddities, and be sure to include the exact error and the 'Tmpfile' value from the top of the import page.
OpenFlights (.csv) — Comma-separated value, exported from OpenFlights 'Export' or 'Backup') and easily edited or created in Excel or any other spreadsheet. See format specification.
OpenFlights normally tries to match airlines and flight numbers to known/current airlines. If you check the box above, all airline names will be preserved exactly as they were before, typos and all.
You will be given a chance to review the flights before they are actually imported. See to backup or clear your flights before importing.