More than a fifth of Ryanair flights faced delays in September due to air traffic control staff shortages.

A total of 15,455 flights – 21% of the total – were affected, according to Europe’s largest short-haul carrier, which carried more than 14 million passengers in the month.

More than 92% of the no-frills airline’s 73,300 flights arrived on-time, excluding air traffic control delays, up from 89% in the same month last year.

Ryanair chief marketing officer Kenny Jacobs said: “ATC staff shortages and disruptions continue to have a large impact on punctuality as we come to the end of summer peak, delaying more than one fifth of Ryanair flights last month – with UK, Germany, France and Spain as the worst ATC providers in September.

“Despite this, our punctuality continues to improve and is up year-on-year.”

The airline reported that 86% of more than 145,000 passengers surveyed rated their flight as ‘excellent, very good or good’.

Crew friendliness received the highest score of 91% while boarding and food and drink choice the lowest at 82%.