Air traffic control problems at Gatwick and national strikes in Italy were blamed by Norwegian Air for flight disruption last month.
The Scandinavian budget carrier said the majority of the few flights that it did not operate in September were due to the two issues.
The fleet of 80 aircraft achieved 99.7% regularity, the share of scheduled flights taking place, the highest level since the pandemic.
The airline saw passenger numbers rise to more than two million in the month, up eight per cent year-on-year.
Punctuality, the share of flights departing within 15 minutes of scheduled time, was at 84.6% in September.
Additional routes to new destinations for next summer will be announced in November, according to the airline.
Chief executive Geir Karlsen said: “September was yet another good month for Norwegian. We had more than two million passengers, and our operational performance is again among the top airlines in Europe.
“Our recorded regularity is now at the strongest level in over 18 months, while our on-time-performance also improves further.
“Our solid and efficient operations provide predictability for all customers that choose to fly Norwegian, either for leisure or business purposes.”
He added: “As we approach the winter season, we have adjusted our operations to align with the travel patterns in the quieter winter trading period.
“A clear and continued trend is that our destinations in southern Europe experience continued robust demand among people from the Nordics.
“In addition, a new trend this autumn is the rise in popularity of city breaks to eastern Europe in particular.”