UAL

(UAL) - Get Report

, the parent company of United Airlines, is searching for a new top executive for the second time in six months.

After the close Tuesday, the company said Jack Creighton, who took the chief executive post last October, is stepping down. Creighton, the former CEO of paper products company

Weyerhaeuser

(WY) - Get Report

, replaced James Goodwin half a year ago.

In a short statement, Creighton, a board member before his elevation to interim CEO, said he was "brought in for the short term to stabilize United and improve the relationship between management and employees. We have made some important strides in each of these areas, and I will continue to focus on those priorities as we search for my replacement."

The outgoing CEO also said that he would "work with the leadership of our unions to find ways to assure the viability of this great company. We confront huge challenges, and we must secure the cooperation and support of our employees if we are to succeed."

UAL has hired Russell Reynolds Associates to conduct a nationwide search for candidates to serve as the next chairman and chief executive officer.

Shares of UAL ended down 33 cents, or 2.3%, at $14.09 on the

New York Stock Exchange

.