What maintenance log evidence do I need for an EU261 delay claim, and can airlines fake an ATC excuse?

If your flight was delayed and the airline blamed air traffic control (ATC) — but you suspect the real cause was a technical or maintenance problem — the maintenance log becomes the single most important piece of evidence in your EU Regulation 261/2004 compensation claim. This article explains what maintenance log evidence is, why it matters, how airlines sometimes misrepresent the cause of a delay, and exactly what you need to prove your case. The short answer: EU261 does not obligate the airline to hand you the maintenance log, but you can request it, and courts across Europe regularly order its disclosure. A delay of 3 hours or more at arrival triggers compensation of €250, €400 or €600 depending on distance, unless the airline proves an extraordinary circumstance — and a genuine maintenance defect generally does not qualify as extraordinary under established case law.

What EU261 Actually Says About Extraordinary Circumstances

Also worth reading: How Does EU261 Flight Compensation Work for AI Airlines? · What Should an EC261 Evidence Checklist Prove for a Flight Delay or Cancellation? · EC 261 Claim Evidence Guide: What Should You Prove in 2026?

Regulation (EC) No 261/2004, Article 5(3), exempts airlines from paying compensation if they can prove the cancellation or long delay was caused by extraordinary circumstances that could not have been avoided even if all reasonable measures were taken. The classic examples are severe weather, air traffic control decisions like flow restrictions or runway closures, security threats, and strikes by third parties unrelated to the airline. The burden of proof sits squarely on the airline, not the passenger. This is a point many travellers get wrong: you do not have to prove the delay was the airline's fault; the airline has to prove it was not.

The Court of Justice of the EU (CJEU) has narrowed the defence considerably over the years. In cases such as Wallentin-Hermann v Alitalia (C-549/07, decided 22 December 2008), the court ruled that a technical problem only counts as extraordinary if it stems from an event outside the airline's normal operations — a hidden manufacturing defect, sabotage, or terrorism. Routine mechanical failures, component wear, and problems discovered during scheduled maintenance do not qualify, because they are inherent to running an airline. Airlines suffer technical issues constantly; that is precisely why the regulation does not treat them as exceptional. Later rulings, including van der Lans v KLM (C-257/14, 2015) on technical problems arising spontaneously, confirmed that even unexpected technical faults discovered during pre-flight checks generally do not release the airline from paying compensation.

ATC restrictions, by contrast, are a recognised extraordinary circumstance under the Commission's 2016 interpretative guidelines. That is why some airlines reach for the ATC excuse when the truth is less convenient — a pattern documented repeatedly by passenger advocates and aviation bloggers, including a widely discussed One Mile at a Time report in which an American Airlines delay blamed on ATC turned out, according to internal accounts, to have a maintenance-related explanation. If ATC truly caused your delay, the airline wins. If the aircraft had a technical defect, you win. The maintenance log is the document that settles the argument.

Why the Maintenance Log Is the Decisive Document

Every commercial aircraft keeps a technical logbook (often called the tech log or the aircraft technical log, formally part of the aircraft's maintenance records under EASA Part-M and FAA Part 91/121 requirements). The captain or first officer writes up every defect reported during each flight sector, and certifying engineers record the corrective action taken, the parts replaced, and the release-to-service entry. Each page is time-stamped and signed. In other words, the tech log is a contemporaneous, legally mandated record of exactly what happened to the aircraft on the day of your flight — written by the crew and engineers themselves, not constructed after the fact for litigation purposes.

If your delay was caused by a failed fuel pump, a cracked cockpit window, or an engine indicator fault, the tech log will show the defect entry, the time it was raised, the corrective maintenance action, and the delay code assigned. IATA delay codes are telling here: codes in the 40s (41–48) typically denote technical or maintenance causes, while codes in the 70s and 80s (e.g. 77, 81–87) denote ATC and airport/ government causes. Internal delay codes appear in the airline's own operations reports. A passenger who can show a tech log entry describing an engine fault at 09:40 on the day of the flight has effectively demolished an ATC excuse that was never plausible in the first place.

Conversely, if the airline's story is true — say, ATC imposed a ground stop due to thunderstorms — the tech log will be clean for that sector, and the airline's internal documentation will show the ATC restriction notice. Either way, the log resolves the dispute, which is why aviation litigation lawyers describe the maintenance log as the single most requested document in delayed-flight court cases in Germany, the UK and the Netherlands.

Comparison: Evidence Sources for Proving the Real Cause of a Delay

Start by writing to the airline's customer relations department and asking, in writing, for the specific reason for the delay and the maintenance status of the aircraft operating your flight number on the date in question. You are not legally entitled to the full tech log under EU261 itself, but many airlines will state the cause in their reply — and if that reply contradicts what the crew announced on the day, you already have a useful inconsistency. Ask a precise question: "Was the delay of flight XX123 on [date] caused by a technical defect in the aircraft, and if so, please provide the defect description and the corrective action taken under Article 5(3) of Regulation 261/2004?" Keep the wording factual; you are inviting the airline to commit to a story.

If the airline refuses or gives a vague answer, escalate to the national enforcement body (NEB) responsible for the departure airport — for example, the CAA in the UK, the LBA in Germany, or the competent authority in the country of departure. NEBs can request operational records from the airline and, in many jurisdictions, have powers to require the production of documentation. A complaint to the NEB is free of charge.

The strongest route is the courts. In Germany, UK county courts (pre-Brexit cases under retained EU261), Dutch and Spanish courts, judges routinely order disclosure of the tech log pages and internal delay codes where the cause of the delay is disputed. Airlines know this, and a surprising number settle once a claim reaches the point where disclosure is imminent — because if the log shows a technical defect, the airline not only loses but may face adverse costs. Services such as AI Flight Refunds can automate the initial claim, draft the escalation letters, and hand the case to partner law firms who pursue court-ordered disclosure of maintenance records at no upfront cost to you; the firms work on a success-fee basis, typically retaining 20–35% of the awarded compensation only if they win. Going alone is free but slower; specialist help costs nothing upfront but reduces your net payout if successful.

When ATC Excuses Are Suspicious — and When They Are Genuine

Not every ATC claim is a lie. Europe genuinely suffered major ATC disruption in recent years: French air traffic controller strikes (which the CJEU in Krüsemann, C-195/17, held do count as extraordinary only if the airline could not reasonably have avoided the impact — re-routing or re-timing can defeat the defence), the 2023 NATS technical failure in the UK that grounded over 1,000 flights in a single day, and chronic staffing shortages at Eurocontrol-regulated area control centres causing flow restrictions across 2022–2024. If EUROCONTROL published flow measures affecting your route and airport on your travel date, the airline's excuse deserves the benefit of the doubt.

Suspicious signs include: the ATC excuse appearing in the reply letter but never having been mentioned by the crew at the airport; identical ATC language used for multiple flights on the same route across different days; delays announced as a "technical problem" on the day that magically become "ATC restrictions" in writing; and refusal to answer any direct question about the aircraft's technical status. Aviation journalists and bloggers have documented cases — including the American Airlines incident referenced above — where passengers' contemporaneous recordings of gate-agent and pilot announcements directly contradicted the airline's written explanation. Record announcements on your phone, screenshot app and gate-board messages, and photograph the departure boards. These small acts of evidence-gathering take seconds and routinely decide claims months later.

Common Mistakes That Destroy Otherwise Strong Claims

The most frequent error is accepting the airline's first rejection letter at face value. Airlines reject a large share of valid EU261 claims on first response, often citing extraordinary circumstances without any supporting evidence, precisely because most passengers give up. A standard template rejection is not the end of the process; it is the beginning of the escalation ladder.

The second mistake is failing to preserve contemporaneous evidence. Crew announcements, gate screenshots and app notifications disappear quickly, and airlines later deny that any technical announcement was made. Recording the pilot's announcement in a German or UK airport is lawful in most cases for personal documentation purposes (check local rules; Germany requires all parties' consent in strict readings, but a factual announcement at a gate is generally treated differently — when unsure, write down the words immediately instead). The third mistake is claiming against the wrong party, such as a codeshare partner: EU261 compensation is payable by the operating carrier, not the marketing carrier whose name is on the ticket. Fourth, passengers often mis-record the arrival time — compensation thresholds depend on arrival at the destination gate, not departure, so a 2-hour-50-minute departure delay that becomes a 3-hour-10-minute arrival delay still qualifies for the full amount under Sturgeon v Condor (C-402/07). Finally, watch the time limits: in the UK it is six years from the flight, in Germany and Spain three years, in France five years, in the Netherlands two years, and in Italy two years. Miss the deadline and the claim dies regardless of the evidence.

What Your Claim Is Worth and When to Act

Compensation amounts under EU261 are fixed by distance and delay length, not by the cost of your ticket. You receive €250 for flights up to 1,500 km delayed 3 hours or more at arrival; €400 for intra-EU flights over 1,500 km and all other flights between 1,500 km and 3,500 km; and €600 for flights over 3,500 km (reduced to €300 if the arrival delay is between 3 and 4 hours on long-haul routes). If the airline re-routes you and you arrive within 2, 3 or 4 hours of the original schedule (by distance band), compensation is reduced by 50%. On top of compensation, Article 9 entitles you to a right to care after 2–4 hours of delay depending on distance: meals, refreshments, two free communications, and hotel accommodation plus transfers for overnight delays.

Act quickly regardless of deadlines. The tech log's crew entries are clearest in the days after the flight, witnesses remember announcements better, and airlines' own operational records are less likely to have been archived or purged. A claim filed within weeks of the delay faces far less resistance than one filed two years later. As of 2026, note that the EU has been debating a modernisation of the Air Passenger Rights Regulation that could change thresholds and amounts, but EU261/2004 remains the law in force across all EU member states, plus Norway, Iceland and Switzerland, with a mirroring scheme (UK261) in the United Kingdom following Brexit.

Bottom Line on Maintenance Logs and ATC Excuses

The maintenance log is not something you can demand as of right over the counter, but it is the document that decides disputed EU261 claims, and courts will order its production when an airline's explanation looks shaky. Your practical path is: document everything on the day, ask the airline precise written questions about the cause, escalate to the national enforcement body if you get a template rejection, and take the claim to court — directly or through a claims service — where disclosure of the tech log and delay codes becomes available. Remember that a technical defect is almost never an extraordinary circumstance under CJEU case law, so if the log reveals maintenance trouble behind a fake ATC story, the €250–€600 compensation is yours to claim.

Whether you pursue it yourself or use a service like AI Flight Refunds, which applies the full EU261/2004 framework and escalates to legal action where airlines stonewall, the winning formula is the same: contemporaneous evidence, a precise written record of what the airline told you, and persistence through the escalation ladder. Airlines count on passengers walking away after one rejection letter. The maintenance log — and the law — are on your side if you don't.