KUALA LUMPUR, April 20 — Christoph Mueller, the chief executive of Malaysia Airlines Bhd, told his staff he was leaving the national carrier for reasons that are personal and “beyond my control,” according to a letter he wrote to them.

“The show must go on,” Mueller wrote to employees yesterday, informing them he was leaving the carrier in September, according to a copy of the letter seen by Bloomberg News. The resignation is for “personal reasons, which are beyond my control,” Mueller wrote without elaborating.

Mueller’s unexpected resignation comes as the carrier is beginning to turn around after two plane crashes in 2014 dented its sales and reputation, prompted the government to buy out all shareholders and take the company private. A veteran of a turnaround effort at Aer Lingus Group Plc in Ireland, Mueller was charged with reviving a carrier that was racking up losses even before hundreds of people died in the two crashes.

“The company is making very good progress and we are on track with our plan,” Mueller wrote. “We have delivered our financial budget for the first three months of 2016, our on-time performance is increasing and very stable and our customer service index is recovering with more significant improvements in the pipeline.”

Phone calls to Malaysia Airlines’s public relations department and to Mueller’s office weren’t answered.

On track

After cutting 6,000 jobs, reducing pay, and trimming capacity by 30 per cent, the onus is now on Malaysia’s government to find a successor to continue the revival plan put in place by Mueller, who became CEO-designate in March 2015. State sovereign-wealth fund Khazanah Nasional Bhd. took the carrier private by buying out small shareholders to help the Sepang, Malaysia-based company return to profit.

Malaysia Airlines is on track to return to profitability as the airline’s restructuring effort is proceeding as planned and the company is finished laying off employees, Mueller said in an interview in February. The carrier wants to buy and own some aircraft once its targets are met, as its existing fleet structure is skewed toward leased planes, he said.

Sad to leave

Mueller intends to remain with the company as a non-executive director and will serve a six-month notice period until September to facilitate an orderly transition, the airline said. The board has appointed Chief Operations Officer Peter Bellew as an executive director, it said.

“We have already seen a profit in February and we are also ahead of budget, which gives a strong indication that our turnaround initiatives are pulling faster than expected,” Mueller wrote in the letter. “Therefore, I feel particularly sad to leave the company when we see the first pay back of the hard work of the team.”

Malaysia Airlines made its first small monthly profit in “many years” in February and is on track to return to profitability by 2018, Mueller wrote in a circular to staff on March 28, Malaysian Reserve reported. A network restructuring aimed at establishing the company’s Kuala Lumpur base as a hub for regional travel is 90 percent complete, he said in November.

Malaysia Airlines was already losing money before passenger confidence was shattered after Flight MH370 vanished on March 8 while en route from Kuala Lumpur to Beijing. The carrier lost another aircraft when MH17 was shot down over Ukraine four months later. — Bloomberg