After suffering a heart attack that led to his hospitalization on Oct. 15, United Airlines' parent company's Chief Executive Officer Oscar Munoz is finally returning to work in early 2016 following his three-week medical leave. The announcement was personally made by Munoz on Thursday.

According to the experts, Munoz's announcement will finally end the uncertainty on the leadership changes that plague United Airlines. As previously reported, the second-largest U.S. airline by capacity has initially appointed 46-year-old Brett J. Hart, United's general counsel, as the company's acting CEO.

However, Brett's appointment gained unfavorable reactions from industry experts, who voiced their apprehensions on Hart's background as a lawyer and his limited experience in finance and operations, which will just further boost the turmoil in United Airlines.

"Mr. Hart has limited experience in finance, operations or customer service, the areas that (United) is most in need of improving - we would have preferred an interim leader with more experience in these areas," S&P Capital IQ analyst Jim Corridore said at the time of Brett's appointment.

Now, United Airlines' CEO Oscar Munoz, who took the CEO position in September, has announced his imminent comeback in the first quarter of 2016, Reuters revealed.

"I am excited to tell you that I am on the road to recovery," Munoz wrote in a letter that was made public after markets closed, as per Chicago Tribune. "My time away will be a little longer than I would like, but based upon discussion with my doctors I will be back in the first quarter."

Munoz, who has suffered a heart attack in his sixth week on the job, has been concentrating to rebuild the morale of United Airlines after years of strained labor relations. And since he has been traversing the United States to hear from employees and customers on how to improve the company, he also wrote a letter of gratitude to his employees.

"Thank you for all the thoughts and prayers you sent to my family and me over the past few weeks," Munoz wrote to employees. "I'm personally grateful to Brett and the entire management team for their leadership and for embracing United's new direction... While I have been part of the United family for only a short time, I've built many valued and strong relationships so far, and I can't wait to come back."

"As I'm sure you can appreciate, this has been a difficult time for me and my family," Munoz added. "Your messages of encouragement have helped profoundly. I look forward to seeing you in 2016 to continue working together to build a great airline."

On Sept. 8, 56-year-old Munoz, who was a top executive at rail company CSX, suddenly and unexpectedly became United Airlines' CEO, taking over ousted CEO Jeff Smisek. Smisek abruptly resigned along with two top lieutenants due to ongoing internal and federal criminal investigations associated with a New York-area port authority scandal.

Meanwhile, United Airlines reported a third-quarter profit of $1.7 billion last month, compared with $1.08 billion in the same quarter last year. And on Thursday, the company's stocks were little changed, up 0.02 percent to $60.30 on the New York Stock Exchange, Bloomberg Business reported.