Korean Air saw the number of passengers on international flights drop 4.6 percent on-year in April, the first time in 23 months that numbers are down. The figure for Asiana Airlines rose 4.6 percent last month.
Incheon International Airport Corp. on Wednesday said Korean Air carried 1.07 million passengers on international routes in April, down from 1.12 million a year ago.
Asiana's passenger numbers rose 34,686 to 792,588 over the same period.
The figures are only those for flights to and from Incheon International Airport.
Korean Air attributed the fall to the North Korean nuclear threat and the weak Japanese yen. "Due to the weak yen, the number of Japanese passengers dwindled significantly, but we saw a 2 percent increase in the number of passengers bound for Japan," a spokesman for the airline said.
It was more affected by the North Korean threat than Asiana because it offers three times more flights to North America, the airline added.
A recent incident involving an abusive POSCO Energy executive onboard may also have damaged business. The executive abused a flight attendant physically and verbally because he was unhappy with the service, and an air log describing the incident in detail spread through social networking sites. But Korean Air said the news broke after April 20, the cutoff date for monthly figures, and therefore had nothing to do with the drop in numbers.