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Evidence before certainty

How the UK flight compensation checker reaches an estimate

The model applies published UK route, timing, distance and cause tests in a fixed order. It deliberately returns uncertainty when the facts are incomplete.

Source hierarchy

  1. UK legislation and GOV.UK guidance.
  2. UK Civil Aviation Authority passenger guidance.
  3. Official airline claim and disruption pages for submission links.
  4. Third-party material only for commercial comparisons, clearly labelled.

Calculation order

  1. Check whether the route and operating carrier fall within UK261 scope.
  2. Apply the three-hour final-arrival threshold or cancellation notice and rerouting tests.
  3. Apply the current £220, £350 or £520 distance band and any permitted 50% reduction.
  4. Keep the cause as unverified until the airline provides specific evidence; a passenger-selected category never proves the legal test.
The calculator can identify two specifically selected airports and calculate their great-circle distance locally. It does not look up a live flight, determine the true disruption cause or replace evidence from the operating airline.

Local airport and distance recognition

  • Airport identity: the passenger must select two specific three-letter airport codes. A city such as London is never silently treated as Heathrow.
  • Static source: the checked-in airport snapshot is generated from the public-domain OurAirports dataset. The source expressly provides no guarantee of accuracy or fitness for use.
  • Coverage: the snapshot includes IATA-coded airports that the source marks as having scheduled service. An airport that cannot be found falls back to the manual questions.
  • Distance: the checker uses the great-circle route between the selected airport coordinates, following the method stated in UK261 and CAA guidance.
  • Boundary safety: a calculated distance within 25 km of 1,500 km or 3,500 km is labelled for review and produces a safe payment range. The 25 km margin is a conservative product rule, not a legal threshold.
  • Connections: flights on one booking use the first departure and final destination. Separately booked self-transfer flights must be checked individually.

Airport and distance recognition can be high confidence after exact airport selection. UK261 scope for a flight leaving another country still depends on the actual operating airline shown by “Operated by” on the booking. A marketing flight-number prefix is not used to guess the operator.

What appears in a result

  • Checks applied: route, timing or notice, rerouting, cause and amount bands that were relevant to the answers.
  • Expandable basis: every result links the applied checks to current legislation or official guidance without crowding the main result.
  • Assumptions: confirmed reservation, eligible fare, timely check-in where required, one overall booking and any relevant overseas compensation remain visible for the passenger to confirm.
  • Evidence to collect: documents and facts that can support a direct airline complaint.
  • Unknown items: facts that this browser-only tool cannot verify, including airline operational evidence.
  • Next steps: a direct-airline-first sequence, not a claim acceptance or payment guarantee.

Result labels

Strong initial match
The supplied facts pass the applicable first checks. It is still an estimate, not a payment decision.
Needs evidence
The route and timing pass, but a material fact such as the cause remains unverified.
Fixed compensation unlikely
At least one selected fact does not pass a fixed-compensation gate. Separate care, refund or rerouting rights may remain.
Another rule may apply
The selected route and operating-airline region do not pass the UK261 route test; another passenger-rights regime may still apply.

Testing and change control

The rule engine is separated from the interface and covered by automated tests for route scope, delay thresholds, extraordinary circumstances, cancellation notice and replacement-flight reductions. A material rule change requires updated tests and a dated entry in product updates before publication.

Review and corrections

Passenger-rights rules were last reviewed on 10 August 2026. Airline form and complaint routes have their own review date. Material rule changes require updated tests before publication. Send corrections to support@delaydesk.com.