Kenya Airways Chief Executive Officer Sebastian Mikosz will step down from the troubled state airline five months before the end of his three-year contract, according to a staff memo seen by Bloomberg.

“I have made the decision to shorten my contract term and I have decided to resign on personal grounds effective Dec. 31,” Mikosz said in the letter sent to employees, without giving a reason. The CEO didn’t answer calls to his phone seeking comment.

The decision by the former CEO of Polish government-owned carrier LOT comes after Kenya Airways reduced losses to just under 6 billion shillings ($59 million) in the year through March 2018 from a record 26.2 billion shillings two years earlier. Sub-Saharan Africa’s third-biggest carrier by passenger traffic has a plan to be profitable in 2022, though this is dependent on gaining government approval to become the operator of Nairobi Airport.

The airline’s board agreed to Mikosz’s resignation and would begin recruiting a successor, according to a letter that the company sent to the Capital Markets Authority and seen by Bloomberg.

Kenya Airways is 48.9% owned by the Kenyan government, which increased its stake as part of a bailout plan in 2016. Air-France KLM is a minority shareholder. The shares rose 5.2% to 3.63 shillings in Nairobi on Friday, valuing the carrier at 5.4 billion shillings.