Incheon Airport and Singapore Airlines are facing protest from a family after a passenger reportedly suffering from mental illness jumped from the fourth floor of Incheon Airport's concourse while waiting for a transfer flight to Los Angeles in mid-December.

The man's family claims that Singapore Airlines, which operated his flight, and Incheon Airport Corporation should be held responsible, according to news reports.

The 52-year-old American man, who was travelling in Thailand, decided to return to his home in Los Angeles when his bipolar symptoms reportedly became more severe. His family reportedly wrote to Singapore Airlines to alert them of his condition and ask for special attention.

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The man's symptoms raised concerns among flight crew on the flight from Thailand to Incheon Airport, according to the air carrier.

"Our cabin crew managed to calm and control the customer, who was handed over to airport security staff upon arrival in Seoul," Singapore Airlines said in an official statement. "Singapore Airlines apologises to the customers on the flight who were affected."

While waiting for a transfer at Incheon Airport, Singapore Airlines decided that the man needed special care and asked Incheon Airport for support. The man was put under the care of a security official at the airport on Dec. 18.

"We received a request from Singapore Airlines and agreed to allow the passenger to stay at a hotel within the transfer centre," said a spokesperson for Incheon Airport. "We also kept an eye on him and did what we could, but at an airport where 200,000 people transit every day it is impossible for us to control any one passenger's movements."

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On Dec. 19, the man was caught on CCTV cameras moving from the hotel toward the concourse. He jumped from the fourth floor down to the lobby on the third floor and was immediately moved to a nearby hospital. He remains in critical condition.

Neither Singapore Airlines nor Incheon Airport said they have received an official notice from the man's family asking for compensation.

Incheon Airport denies any liability, while Singapore Airlines told The Korea Herald that any official stance on responsibility is "currently being discussed."