* Both AMR, US Air boards OK merger, deal announcement Thurs
* AMR creditors OK merger earlier on Wednesday -sources
* Deal to value combined airline at around $11 bln -sources
* Merged American-US Air to have 12-member board -sources
* AMR unsecured creditors to be made whole plus accrued interest
By Soyoung Kim
NEW YORK, Feb 13 (Reuters) - The boards of AMR Corp and US Airways Group Inc separately met on Wednesday to approve a merger that would value the combined company at around $11 billion, people familiar with the matter said.
The deal, which will be announced early on Thursday, comes more than 14 months after the bankrupt parent of American Airlines filed for bankruptcy in November 2011, and would mark the last combination of legacy U.S. carriers, following the Delta-Northwest and United-Continental mergers.
The board approval came after AMR's unsecured creditors committee, which includes all three of AMR's major unions, met earlier in the day to approve a proposed merger agreement, the people said.
The all-stock merger would give AMR creditors 72 percent of ownership in the merged entity and US Airways shareholders the rest, the people said.
The merged company will have a board of 12 members: four from US Airways including its chief executive Doug Parker, three from AMR including chief executive Tom Horton and five to be designated by the AMR creditors, one of the people said.
That will shrink to 11 members in 2014 after Horton steps down following the combined company's first annual meeting, the person added. Parker becomes chief executive of the new airline.
AMR's unsecured creditors are expected to be made whole on their claims in the form of stock in the merged company and also get accrued interest, the people said. AMR's shareholders will get a small equity stake as well, they added.
All the sources asked not to be named because the matter was not public. US Airways declined to comment while AMR representatives could not be immediately reached for comment.
A tie-up with US Airways would create the world's top airline by passenger traffic and help American and US Air better compete with United Continental Holdings and Delta Air Lines.
Some $11 billion valuation of the combined American-US Airways compares to the roughly $12.4 billion market capitalization for Delta, and $8.7 billion for United Continental.