Ryanair has been cleared to describe itself as 'Europe's No.1 airline' following complaints that widespread cancellations last year made the claim misleading.
The TV and radio ads in September and October included voice-overs saying: "Discover why more and more people are choosing Europe's number one airline" and "Discover why we're Europe's number one airline".
A poster ad, seen on the London Underground on October 2, featured the headline claim: "Europe's No.1 Airline."
The Advertising Standards Authority (ASA) received 13 complaints from people who claimed the ads were misleading in light of Ryanair cancelling tens of thousands of flights last year because of errors in how pilots were rostered for work.
Ryanair said the number one claim was a statement of fact, supported by a third-party statistical report, and therefore not misleading.
They said the claim was based on the most recent International Air Transport Association (IATA) World Air Transport Statistics 2017 report for air travel in 2016, which found Ryanair was the world's largest airline for international flights and Europe's largest airline for international and domestic flights combined.
Ryanair said their recent cancellation of flights, which affected less than 0.5% of their 129 million customers last year, did not materially alter this fact.
The ASA said consumers were likely to understand the number one claim to mean that Ryanair had carried more passengers than any other European airline over a reasonable time before the ads were produced.
It said: "While we acknowledged some of the complainants' views of Ryanair were that it was not their personal number one airline due to the recent flight cancellations, we considered they would nevertheless still interpret the claim to be an objective statement about the number of passengers who had travelled on Ryanair flights compared to all other European airlines.
"Because the most recent available figures showed Ryanair had carried more passengers than any other European airline, we concluded that the claim 'Europe's No.1 Airline' was unlikely to mislead consumers."