Malaysia Airlines CEO Christoph Mueller will leave his job in September, way ahead of the end of his three-year contract, due to his “changing personal circumstances.”

The airline said Tuesday it has begun searching for a new CEO from a pool of internal and external candidates. Its statement said Mueller will serve a six-month notice until September to ensure a smooth transition, and will stay on as a non-executive director.

Mueller, a turnaround veteran, formally began his job in May last year to oversee a $1.56 billion overhaul that included cutting 6,000 jobs and axing unprofitable routes.

“I am proud of what we have achieved as a team in such a short time….unfortunately, personal circumstances will make it difficult for me to complete my full term,” Mueller said in the statement, without elaborating.

He said he was confident the airline is on the right track to succeed in its next phase of growth under a new CEO and that he remained committed to facilitate its continuing turnaround.

The national airline suffered years of financial losses before the twin disasters in 2014, the disappearance of Flight 370 and the loss of another plane shot down over Ukraine. The airline was taken private by state investment agency Khazanah Nasional and Mueller was hired to oversee the company’s overhaul.

Khazanah said in a separate statement that Mueller has put in place a strong management team and helped lay the foundation for a sustained turnaround that has produced encouraging signs of progress.

In an interview with the Associated Press two weeks ago, Mueller described the airline as a “ship that has many leaks” but said things are back on the right track. He said the carrier recorded a profit in February, its first positive monthly result in years, and is on track to return to the black by 2018.

Photo Credit: A Malaysia Airlines Boeing 737-800 plane sits on tarmac at Kuala Lumpur International Airport in Sepang, Malaysia. Vincent Thian / Associated Press