The flight carrying 125 passengers departed from Incheon International Airport on Saturday.
About 50 minutes after takeoff, the crew detected an issue with the plane's pressurization system as it flew over Jeju Island, Korea JoongAng Daily reported.
Due to the cabin depressurization malfunction, the aircraft was found descending from a cruising altitude of 9,100 meters to 2,700 meters, according to data from flight tracking website Flightradar24.
The sudden change in cabin pressure caused health problems for some passengers, forcing the captain to return to Incheon Airport at around 7:40 p.m.
15 passengers suffered from eardrum pain and hyperventilation, Korea Times reported citing a source from the Ministry of Land, Infrastructure and Transport. Among them, 13 were taken to a local hospital.No serious injuries have been reported.
The flight resumed on Sunday morning with a different aircraft and arrived in Taiwan safely.
The Korean Air spokesperson said the airline was currently investigating the exact cause of the diversion.
