The court's ruling on the "nut rage" case sent shockwaves through Korean Air, which had reportedly hoped for a suspended jail term for its heiress and former vice president Cho Hyun-ah.
The nation's largest full-service carrier avoided officially responding to the court's sentencing of Cho to one year in prison.
"We have nothing to say on the verdict," a company official was quoted as saying.
Another official said the company would not issue a statement on the ruling.
According to Yonhap, a somber mood prevailed at the company's headquarters in central Seoul after the ruling was announced.
Some observers said the news threw cold water on the carrier's impressive turnaround in earnings.
Korean Air said it posted 11.9 trillion won (S$14 billion) in sales in 2014, up 0.5 per cent from the previous year.
The carrier's operating profit stood at 39.5 trillion won, bouncing back into the black from minus 19.6 billion won in 2013. However, it had a net loss in the fourth quarter of minus 271.9 billion won, up 19.4 per cent from the previous quarter.
The slump in oil prices added up to big savings and helped boost the firm's operating profit, analysts say.