Why airfares change: Dutch regulator calls for clearer explanations

The Netherlands Authority for Consumers and Markets, ACM, wants businesses to explain more clearly how pricing algorithms work. Research published on 28 September examines changing airfares and the uncertainty they create for travellers. The findings and recommendations are provisional.

One flight, dozens of prices

Passengers pay an average of 30 to 35 different prices for the same basic ticket during a flight’s sales period. ACM analysed more than 14 million transactions across 56 selected routes, covering flights operated between July 2022 and July 2025.

Airlines consider factors including the destination, travel period and expected demand. Prices can change when seats sell faster or slower than anticipated. Seeing a higher fare when you search again therefore does not establish that the airline is charging you personally more.

Clearing cookies does not help, according to the research

ACM says previous searches and the device used currently have no influence on the airfares examined. Clearing cookies or booking on another phone therefore offers no advantage for this purpose.

Nevertheless, 46% of surveyed ticket buyers believe previous searches affect prices. A quarter believe the device matters. The accompanying consumer research highlights widespread uncertainty about pricing algorithms.

No guaranteed cheapest booking date

ACM observed that average fares for European flights initially declined gradually, before rising sharply around two months before departure. That overall pattern cannot predict the cheapest booking date for your particular flight.

Our practical takeaway: compare matching travel dates and ticket conditions, including the extras you need. Make your decision using the total cost and your travel plans; the research provides no guaranteed booking shortcut.

What happens next?

Consumers and other interested parties can comment on the draft report until 9 November 2026. ACM expects to publish its final report by the end of 2026. This publication does not itself change the rules for booking flights.