Uber Technologies Inc. officially welcomed its new chief executive Dara Khosrowshahi, who has led online travel business Expedia Inc. for 12 years, in a note sent to employees of the world’s biggest ride-services company.

The board had already selected Khosrowshahi as Uber’s next CEO in a vote on Sunday, two sources said. But the firm and its board had not spoken publicly on the decision until Tuesday evening.

Khosrowshahi’s appointment comes at a time when Uber is trying to recover from a series of crises that culminated in the ouster of its former CEO Travis Kalanick in June. It is also a key step towards filling a gaping hole in its top management which at the moment has no chief financial officer, head of engineering or general counsel.

One of the toughest decisions of my life

“The board and the executive leadership team are confident that Dara is the best person to lead Uber into the future,” Uber’s eight-member board wrote in an e-mail to employees that was also made public.

Khosrowshahi e-mailed Expedia staff that he had accepted the job of Uber CEO, albeit “with truly mixed feelings”.

“This has been one of the toughest decisions of my life,” he said in his e-mail.

Over his tenure, Khosrowshahi built Expedia into the largest online travel agency by bookings and its stock price grew more than six-fold since he became CEO in 2005.

“I have to tell you that I’m scared,” he wrote in the note.

“I’ve been here at Expedia for so long that I’ve forgotten what life is outside of this place.”

He joined San Francisco-based Uber’s all-hands staff meeting yesterday to take questions from employees and will also over the next few weeks meet with employees around the world and with drivers.

Khosrowshahi, 48, is an Iranian immigrant who came to the US with his parents in 1978 during the Iranian Revolution. He is described by those who know him as a friendly and steady hand, savvy businessman and calming influence in situations of chaos.