Methodology
Did the airline blame the weather? This is how we check the evidence
For many airlines, 'unfortunately, weather conditions' is the end of the conversation. For us it is the beginning: the weather at an airport is officially recorded every half hour, and those records do not lie.
6 min readBy the Tomo editorial team
Why the weather excuse comes up so often
In extraordinary circumstances an airline owes no compensation, and weather is the most used variant: it sounds credible, it feels unverifiable, and nobody at the gate asks for proof. In rejection letters it is a fixed routine.
But the regulation puts the burden of proof on the airline: it must show that the cancellation or delay was caused by extraordinary circumstances that could not have been avoided even with all reasonable measures. Our job is to take that proof seriously — and to check the numbers behind it.
What METAR is
METAR is the international reporting format in which airports record their current weather: visibility, wind, cloud, precipitation, temperature and special phenomena such as thunderstorms or freezing rain. Pilots and air traffic controllers plan their operations with it.
Virtually every commercial airport publishes such an observation, usually every half hour, in a standardised form that reads the same worldwide. That makes it possible to reconstruct exactly what the weather was at the moment your flight was due to depart or land.
Our sources
We use exclusively public, official sources: the METAR feeds of aviationweather.gov, the service run by the US agency NOAA, and the historical METAR archives of the Iowa Environmental Mesonet at Iowa State University, which keeps observations from airports worldwide going back years.
Both sources are freely accessible. Every observation we show, you can look up and verify yourself — exactly as it should be for a test that claims to prove something.
How the test works
For every claim we pull the METAR observations around the scheduled departure time at the departure airport and around the scheduled arrival time at the arrival airport. We assess them against thresholds that genuinely affect flight operations: visibility and cloud base, strong wind and gusts, thunderstorms in the vicinity, snow or freezing rain.
On top of that comes the legal core: bad weather somewhere is not yet an extraordinary circumstance for your flight. The weather must have affected that specific flight, and the consequences must have been unavoidable even with all reasonable measures. If the rest of the schedule flew as normal that day, the excuse starts to creak.
An example (hypothetical)
Suppose an evening flight is cancelled and the airline writes 'storm at the departure airport'. We pull up the records, and around the scheduled departure time they show visibility 9999 — meaning 10 kilometres or more — and a wind of 8 knots, a moderate breeze. At the arrival airport: the same picture.
This example is expressly hypothetical, but the pattern is exactly what the test is meant to catch: a weather excuse that does not match what the official observations show. In such a case we put the METAR lines next to the rejection and ask the airline to substantiate the excuse — or to pay.
What this means for your claim
If you run our free check, the result shows you the METAR records around your flight times. You do not have to take our word for it: the weather picture we base ourselves on is right there.
If the observations do support the weather excuse, we say so honestly — a compensation claim is then usually hopeless and we will not waste your time. Your right to care and to rebooking or a refund still stands even in genuinely severe weather, by the way.
For newsrooms and researchers
Writing about cancellations, weather or passenger rights? The METAR tests we publish can be cited with the attribution 'source: TomoClaim' plus a link to the relevant page.
The underlying observations remain those of the official sources — NOAA and the Iowa Environmental Mesonet — so feel free to credit them as well. We are happy to answer questions about the method.
Further reading
Step-by-step
Flight delayed, what now? What to do at the airport
From the first announcement to claiming at home: the step-by-step plan that strengthens your claim while you wait.
4 min read →
Your rights
Extraordinary circumstances: when may an airline really refuse?
Technical faults, storms or strikes: airlines call almost everything force majeure. The courts see it far more strictly.
5 min read →
Topical
Strike at the airport? These are your rights
In a strike everything depends on who is striking. The difference between airline staff and everyone else is worth hundreds of euros.
4 min read →
Action plan
Flight cancelled, what now? The action plan for the first 60 minutes
Don't panic: what you sort out in the first hour decides how smoothly your trip continues and how strong your claim stands later.
5 min read →
Explainer
EUclaim is bankrupt — what does that mean for your claim?
Dutch claim agency EUclaim has been declared bankrupt. What it means for pending and new claims — and why your right to compensation still stands.
6 min read →
Find out in 2 minutes what your flight is worth
Free and without obligation. We do the work; you only pay when we win.