How we keep the data current

Update log

Airlines change their pet rules without telling anyone. When ITA raised the limit to 12 kg on domestic flights, or when SWISS revised the carrier dimensions, there was no press release: a page changed. So an automatic check reads the official pages every week and flags when they are no longer what they were.

Recorded changes

How the check works

Every week a script downloads the official policy page of each monitored airline, reduces it to readable text and compares it with the previous version. Before comparing, session tokens, timestamps, dates and times are stripped out: they change on every load and, without that cleanup, every airline would look “changed” every week — which is the same as the log saying nothing.

The real comparison runs over a narrow list: every numeric value with a unit found on the page. Weights in kilograms, carrier dimensions in centimetres, fees in euros or dollars, hours and days of advance booking. That is the part that matters, and the only part that can make a figure published here wrong.

Hence the two labels in the log:

What a change does not mean

The check is automatic, and an automation sees differences, not meaning. A new number may come from a promotion, from a table in another section, or from an airline's own mistake that stayed online for half a day. That is why no change is published on its own: it goes into a queue, someone reopens the official page, compares it, and only then does the entry appear here and the site data get corrected.

The reverse is true too, and it is the honest limit of this method: an airline can change its policy without touching the page we watch — by publishing it only in the conditions of carriage PDF, for instance. The log reduces the risk of a figure going stale in silence; it does not eliminate it.

Which airlines are monitored

Only those whose policy page URL has been opened and verified by hand, comparing what the airline writes with the values published here. For the others we do not know whether the URL is stable, and a false alarm repeated every week is worse than no alarm: it would be ignored within a month.

The number of monitored airlines and the date of the last check are in the metadata of the public API, fields monitored_policies and last_policy_check. This log is readable as JSON too, under the same CC BY 4.0 licence as the rest of the data.

Frequently asked questions

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