The 60-year-old, who has a wealth of experience and expertise working with utilities, will be a part of board's compensation and labor committees.
US Airways’ Chairman and CEO Doug Parker said, "We are extremely pleased to welcome Bill to US Airways. He is a seasoned corporate leader with extensive experience operating in a complex and highly regulated environment.
“US Airways will benefit from Bill’s broad business knowledge and strategic perspective, and we expect that he will be a significant contributor to our Board."
At Pinnacle West Corp, Post served chairman of the board from February 2001 to April 2009. He was the CEO from February 1999 to April 2009.
Currently, Post is chairman of the board of Swift Transportation, and director of First Solar and Blue Cross Blue Shield of Arizona.