Methodology and sources

Nothing on this site is estimated. The arithmetic is in /js/payout.js, which runs in your browser and at build time, and the data files are public at /data/rules.json, /data/airports.json and /data/airlines.json.

Sources

Airport coordinates

Airport reference coordinates in decimal degrees. Ten files came from OurAirports' public country CSVs; the US and French country files would not load on the check date, so the ten US and French airports use the coordinates in each airport's Wikipedia infobox. Checked 2026-10-20.

Method

• Distance: great circle (haversine) on a sphere of radius 6,371 km between the two airports, as Article 7(4) of EU261 and UK261 requires. Routes are measured airport to airport; on a connecting trip the regulation measures to the final destination.
• Which rule applies: EU261 Article 3(1) and UK261 Article 3(1) by departure airport and the operating airline's licence; APPR for flights to, from or within Canada (Canada Transportation Act s. 86.11(1)); US Part 260 for flights to, from or within the US.
• Amounts: EU261/UK261 Article 7(1) bands; the reduced long-haul amount for arriving 3 to 4 hours late as published by Your Europe (EUR) and the CAA (GBP); Article 5(1)(c) cancellation exemptions; Article 7(2) halving. APPR s. 19 and s. 20. US 14 CFR 250.5 and 260.2.
• Routes: Airport pairs chosen to cover every combination of the four rule sets (UK–US, UK–EU, intra-EU, EU–North America, Canada, US domestic and international) and all three EU261/UK261 distance bands. Distances are not stored: they are computed from airports.json by great-circle at build time. A slice of busy routes, not a ranking. Each page covers both directions.
• Airlines: US airlines: the DOT Airline Cancellation and Delay Dashboard (text version, last updated 3 Dec 2024; the dashboard page was updated 11 Sep 2025) and DOT's Air Travel Consumer Report for June 2026. A 'No' means the commitment is not on the airline's dashboard list; an airline may still provide it at its discretion. Non-US airlines: the claim or passenger-rights page on the airline's own website, found on the check date. Canadian large-carrier status from the Canadian Transportation Agency.

What is left out, and gaps

• Hawaiian Airlines as a separate page: DOT now reports Hawaiian-branded flights inside the Alaska Airlines line, and its dashboard commitments are the same as Alaska's, so it is covered on the Alaska page.
• Spirit Airlines: Not on the DOT cancellation and delay dashboard, and absent from the June 2026 monthly on-time tables.
• Separate pages for non-US airlines: The site found no published, airline-specific delay commitments or punctuality figures for them that it could cite; they are listed with their own claim pages instead.
• Flight-number lookup: there is no free public source of scheduled and actual times for every flight that the site could cite, so the checker asks for the airports and the hours late instead.
• National EU limitation periods: EU261 claim deadlines follow each member state's law (Moré v KLM). They have not been checked against each national statute and are not listed.
• Routes beyond the 53 on the site: the plan called for the top 300; this build covers 53 with verified coordinates. Any pair of the 36 airports can be checked in the tool.
• Non-US airline pages: no airline-specific commitments or punctuality data could be cited, so European and Canadian airlines are listed with their claim pages on the airlines page instead.
• APPR size of non-Canadian airlines: the regulation's passenger test applies, but airlines' figures were not collected; the checker lets you choose.

Data version 2026-10-20.