Analysis engine methodology
How Avyron analyses each claim: legal sources, calculation algorithms, geographic coverage and system limitations.
Last reviewed: May 2026 · Engine version: 1.3
1. Legal framework
EC Regulation 261/2004
The primary regulation on which the engine operates. It establishes compensation, assistance and reimbursement rights for air passengers in the European Union. Published in the EU Official Journal on 17 February 2004, in force since 17 February 2005.
The engine applies the following articles:
- Art. 2 — Definitions (cancelled flight, denied boarding, long delay)
- Art. 3 — Territorial and personal scope
- Art. 4 — Denied boarding (overbooking)
- Art. 5 — Flight cancellation and advance notification
- Art. 5.3 — Extraordinary circumstances (exemption ground)
- Art. 6 — Delays
- Art. 7 — Compensation amounts by distance
- Art. 8 — Right to reimbursement or alternative transport
- Art. 9 — Right to care (food, hotel, communications)
UK261 — United Kingdom equivalent regulation
After Brexit, the UK incorporated EC 261/2004 into its domestic law as UK Statutory Instrument 2018/1311. The engine applies UK261 for flights from or to UK airports with British or EU airlines, assigning the Civil Aviation Authority (CAA) as the competent regulator.
Incorporated CJEU case law
The engine incorporates the interpretation of the following Court of Justice of the European Union rulings:
- CJEU C-402/07 and C-432/07 (Sturgeon, 2009) — Equates long delay with cancellation: the 3-hour threshold at the final destination activates the right to compensation. The engine calculates delay at the final destination, not at departure.
- CJEU C-549/07 (Wallentin-Hermann, 2008) — Technical aircraft faults do not constitute extraordinary circumstances unless they are unforeseeable and inherent to the manufacturer. The engine classifies airline technical faults as non-exempting.
- CJEU C-257/14 (van der Lans, 2015) — Confirms Wallentin-Hermann: routine maintenance does not exempt the airline.
- CJEU C-74/19 (TAP Air Portugal, 2020) — A strike by the airline's own employees is not an extraordinary circumstance. The engine distinguishes between internal strike (does not exempt) and air traffic control strike (may exempt).
- CJEU C-11/11 (Folkerts, 2013) — Delay on a connecting flight under a single ticket is calculated at the final destination. The engine applies this rule in all connection cases with a single booking reference.
2. Data sources
AeroDataBox (via RapidAPI)
Use: Real-time flight data: status, actual arrival time, recorded delay. Allows cross-checking passenger-declared data with airline operational data.
Limitation: Historical data availability depends on AeroDataBox coverage for that route and date.
Internal airport coordinates database (IATA)
Use: Calculation of the great-circle distance between airports using the Haversine formula. This distance determines the compensation band (< 1,500 km / 1,500–3,500 km / > 3,500 km) per Art. 7 EC 261.
Limitation: For non-direct routes (technical stopover without passenger transfer), the distance between origin and final destination airports is used.
Regulator registry by airport (internally compiled)
Use: Assignment table of the competent national aviation authority by IATA airport code of origin. The engine determines the applicable regulator based on where the flight departs and whether the destination is in the EU/EEA.
Limitation: Airports with multiple international/domestic terminals are catalogued under the regulator corresponding to the international flight.
Official regulator and ADR body URLs
Use: Verified table of direct links to the claims portals of 27 national aviation authorities and alternative dispute resolution (ADR) bodies. Includes first-instance court portals for 8 jurisdictions.
Limitation: URLs are manually verified at each engine review cycle. External portals may change without notice.
3. Engine architecture
The engine combines deterministic logic (coded EC 261 rules) with a language model (LLM) for narrative analysis generation. Both layers are separate; the LLM cannot alter the deterministic calculations.
Deterministic layer (not delegated to LLM)
- Distance calculation in km using the Haversine formula on IATA coordinates
- Determination of compensation amount by distance band (Art. 7)
- Eligibility evaluation: territorial scope, incident type, delay threshold
- Assignment of competent regulator by origin airport
- Prescription period calculation by jurisdiction
- Ticket reimbursement eligibility evaluation (Art. 8)
- Selection of verified URLs for airline, regulator, ADR and court route
- Success probability calculation via internal scoring model (see §4)
LLM layer — Claude (Anthropic, Sonnet model)
- Evaluation of the rejection reason provided by the airline (abusive / legitimate / none)
- Drafting the case narrative: legal contextualisation in plain language
- Generation of specific action steps for the particular case
- Evaluation of extraordinary circumstances from the passenger's description
- Analysis of complex cases: stopover with separate tickets and different airlines (interline)
4. Success probability model
The success probability is an estimated indicator, not a guarantee. It is calculated using a scoring system that weights the following factors:
5. Coverage — what cases the engine analyses
Flights departing from any airport in the EU-27, EEA (Iceland, Norway, Liechtenstein) or Switzerland, with any airline
Flights arriving in the EU/EEA/Switzerland from a third country, operated by an airline licensed in an EU member state
Flights departing from or arriving in the UK under UK261 (British Airways, Virgin Atlantic, easyJet, Ryanair, and EU airlines with UK operations)
Delays with arrival at the final destination ≥ 3 hours late
Cancellations notified less than 14 days in advance
Involuntary denied boarding (overbooking)
Flights with a stopover under a single ticket (same booking reference)
Flights with a stopover under separate tickets (differentiated analysis per leg)
Missed connections due to delay of the first leg
Codeshare-operated flights (analyses the actual operator, not the marketing carrier)
Cases with a prior airline rejection (assessment of rejection abusiveness)
Cases where vouchers or alternative compensation have already been accepted (waiver assessment)
Passengers who used OTAs (Booking, eDreams, Kiwi, etc.): differentiated claim routes
Passengers with travel insurance: additional dual-route instructions
Class downgrade: calculation of proportional partial reimbursement
Cases outside the scope of coverage
Domestic flights in a non-EU member state (e.g. domestic flight in the USA, Mexico, Argentina)
International flights between two non-EU countries with a non-European airline (e.g. Delta JFK→Tokyo)
Tickets acquired with miles, points or loyalty programme redemptions (no monetary price paid)
Airline staff passes or industry cards with unconfirmed seats
Delays of less than 3 hours at the final destination
Cancellations notified more than 14 days in advance (no compensation right under Art. 7; reimbursement under Art. 8 may apply)
Damaged, lost or delayed baggage (governed by the Montreal Convention, not EC 261)
Claims for ticket price, fare changes or commercial penalties
Cargo or charter flights without an individual transport contract
6. Covered regulators
The engine automatically assigns the competent regulator based on the origin airport. All 27 EU member states plus the UK, Norway, Iceland and Switzerland are integrated.
7. Update policy
CJEU case law
The engine is updated whenever the CJEU publishes a relevant ruling on EC 261/2004. The update cycle is monthly for new ruling reviews, with immediate incorporation for rulings that modify key interpretations.
Regulator and airline URLs
Verified URLs for regulatory bodies, ADR portals and airline forms are manually reviewed quarterly. Airlines that change their website structure without notice may generate temporarily outdated URLs between review cycles.
AI model
The engine uses Anthropic's Claude Sonnet model for the narrative analysis layer. Model updates are evaluated before adoption using a reference test case set to ensure analysis consistency.
EC 261/2004 reform — Trilogue status
The European Commission proposed a revision of the regulation in 2013 (COM/2013/0130). The trilogue process between the European Parliament, the Council and the Commission is active in 2025–2026. Proposals under discussion include raising the delay threshold from 3 to 4–5 hours and adjusting compensation amounts.
8. System limitations
The analysis is informative, not legal advice
Avyron is not a law firm and does not provide legal services. The analysis assesses the applicability of EC 261/2004 to the data declared by the passenger and provides guidance on next steps. It does not replace consulting a lawyer or guarantee the outcome of any claim.
Dependence on passenger-declared data
The analysis is only as accurate as the data provided. If the passenger declares an incorrect delay, wrong date or wrong airline, the result may be inaccurate.
Extraordinary circumstances require documentation
The engine assesses the reasonableness of the extraordinary circumstance claimed by the airline based on the passenger's description. Without official documentation (NOTAM, airline statement, airport report), this assessment is indicative.
Prescription periods are indicative
Periods are calculated from the declared flight date. National laws may have nuances about the dies a quo (start of the period) that the engine does not apply in all cases.
Probabilities are not statistics of real outcomes
The success probability percentage is calculated using an internal scoring model, not from statistics of cases resolved before regulators. Real success rates vary significantly by regulator, airline and year.
Need more documentation?
For B2B integrations, legal due diligence, EU AI Act compliance review, or service level agreements, write to us with the subject "Legal — [company name]".
business@avyronlegaltech.net
We can provide: EU AI Act Art. 52 compliance documentation, technical system description for DPAs, and data processing agreements (DPA/GDPR) for API integrations.