Belfast International Airport is the second worst n the UK for chances of delays.
The majority of delays last year, according to a BBC investigation were in London's airports, which are Luton, Stansted, Gatwick and Heathrow.
It was revealed that 38,000 out of 199,000 international flights from UK airports to popular destinations were delayed between June and September 2016.
The BBC analysed Civil Aviation Authority data from 25 airports but did not cover flights that were cancelled.
Belfast International Airport was found to be the second worst in the UK for delays - with 23% of all flights being delayed over 30 minutes.
It came in behind Gatwick Airport which experienced the most flight delays last summer, with 30% of all flights recorded to be delayed by over 30 minutes.
The longest delay recorded was a chartered flight from Manchester to Dusseldorf, which was delayed by 779 minutes, or almost 13 hours, last September.
The longest delay for Belfast International Airport was a flight to Burgas which was delayed for 350 minutes.
It was the sixth most-delayed service in the summer of 2016.
A spokesman for Belfast International Airport said: “At Belfast International Airport, we do all we can to minimise delays. Our on-time performance is generally very good , but sometimes we, too, fall victim to things that are outside our control.
"There is congested airspace in London and across Europe and it is clear there is a need to make improvements in aviation infrastructure. Like Gatwick, we are also at the mercy of repeated strike action on the Continent.”