A Korean Air aircraft takes off from Incheon International Airport (Courtesy of Yonhap) Korean Air Lines Co., the country’s top carrier, is set to take measures to normalize international flights as nations worldwide are opening up their borders, treating COVID-19 as an endemic.Korean Air said on Tuesday it plans to raise the supply of international flights to 50% of the pre-COVID-19 levels by September while providing in-flight services such as meals. The flagship carrier is also poised to convert freighters back to airliners to meet the summer holiday demand in July and August.The airline will ramp up services between South Korea's hub airport in Incheon and New York to 12 flights a week in July and 14 in August from the current seven. Flights between Incheon and Washington DC, as well as between Inchon and Honolulu, Hawaii, will be increased to seven times a week from five. It will resume a route between Incheon and Las Vegas, Nevada, next month with three flights a week.For European routes, Korean Air will raise flights between Incheon and Paris to seven from five in July. In Southeast Asia, it will increase services for Bangkok and Singapore routes to 14 a week from 10.BACK TO AIRLINERSKorean Air plans to restore planes that have been used as freighters into airliners. The carrier removed cabin seats in some aircraft to increase space for cargo as it focused more on the freight business to cope with a nosedive in passenger traffic due to COVID-19.The company will reinstate three Boeing 777 aircraft out of ten, which have been carrying only cargoes, from July. It takes about 10 days to convert one of them into an airliner.“We aim to deploy some planes that were used for cargo without removing seats for passenger flights during the peak season,” said a Korean Air official.Employees on leave will be back. Korean Air plans additional service training for flight attendants, who have been away from work for more than three months while strengthening maintenance and safety training for mechanics.“We are considering hiring back some cabin crews that temporarily left in accordance with recovery in passenger flights,” said the official.By Jeong Min Nampeux@hankyung.comJongwoo Cheon edited this article.