Methodology — The Incheon Route Index

Source: Incheon Airport traffic by airline and route (Incheon International Airport Corporation) — Incheon International Airport Corporation (인천국제공항공사), via its open API on Korea’s public data portal (dataset 15160910). Licence: no restriction on use, as stated on the dataset page. Period: 2026-07. Retrieved: 2026-09-11.
Why one airport — how the scope narrowed: The intention was a ranking of Korean international routes, and it could not be built.
The airports corporation’s passenger statistics exclude Incheon, because it does not operate Incheon. A ranking without Incheon is not a ranking of Korean international traffic.
Its flight-performance dataset is a 64-row peak-hour snapshot, not material for a ranking.
The ministry statistics that do cover every airport are listed on the portal as a link only, and the site holding the data forbids reproduction, processing and commercial use.
Combining two corporations’ figures into one ranking is something this site does not do — different publishers give no guarantee of the same counting rules.
So this uses Incheon’s own data, and the index name and opening line say so first.
How the ranking is made: Departing passenger routes from Incheon, both scheduled and charter, summed by country (dropping charter would make that exclusion our judgement). The ranking variable is revenue passengers, with flight counts and the number of airports served alongside. As a check the rows must sum to the published totals, or the build fails.
Passenger columns left out of the ranking: The source carries separate columns for non-revenue and transfer passengers, and neither is in this ranking. Their size, for the same month: 13,812 non-revenue and 405,719 transfers. Transfers are about 12.1% of revenue plus transfers combined, too large to leave unmentioned. Adding them could change the order. This index counts people who bought a ticket and departed from Incheon.
Rows with a blank country were not discarded: 1 charter row in the source has no country name, carrying 509 passengers. It cannot enter a country ranking, so its count and passenger figure are printed at the foot of the index. We do not infer the country from the airport code — that would be inventing a value the source does not have.

Limits worth knowing before you cite this

It is a single month. The API takes no period parameter and returns only the latest month. That month is peak holiday season, which tilts towards leisure destinations. We do not place months side by side.
One airport, not the country. International flights out of Gimhae, Gimpo, Daegu and the rest are not here.
Departures only, passengers only. Arriving routes and cargo exist separately in the source and are not in this index.
A country ranking is not a route ranking. Large countries with many airports rise on the sum, which is why the number of airports served sits in the same row.