United Airlines today announced that Oscar Munoz, the company's president and CEO, is currently recovering well following the heart transplant he received on Jan. 6, 2016.

He is still expected to return from his previously announced medical leave at the end of the first quarter or the beginning of the second quarter of 2016. Brett J. Hart will continue as the acting CEO until Munoz's return.

In a letter to employees on Nov. 5, 2015, Munoz stated that he expected to return full time in the first quarter of 2016. Since his heart attack on Oct. 15, 2015, Munoz has been progressing well, with the assistance of an implanted medical device.

A transplant was considered to be preferable to long-term reliance on the implanted device and was not the result of a setback in his recovery. Munoz had been cleared to return to work prior to the transplant.

Since early December, Munoz had been gradually resuming company-related activities in collaboration with Hart, visiting with employees, and participating in meetings at the company's headquarters.