From Phoenix. And, no, US Airways never served Wichita from Charlotte, which is in itself an issue.
When America West bought US Airways back in 2005, there was a lot of speculation that the combined airline would soon “connect the dots”, link cities, especially in the middle of the country, to both the east (US Airways) and west (America West) portions of the combined system.
At the time of the merger, America West flew to six markets in the Central Time Zone from Phoenix that US Airways didn’t serve: Austin, San Antonio, Oklahoma City, Omaha, Des Moines, and, yes, Wichita. These should have been low-hanging fruit. The markets were known, the airline had name recognition, and the cities close enough to Charlotte, the merged carrier’s biggest hub, that regional jets could fly the routes.
Four years later, the dots still aren’t that connected. CLT-Austin and CLT-San Antonio flights finally did start last year. Omaha and Des Moines though are both closer to Charlotte than Phoenix — and still only have serve to PHX. (US Airways ended all service to Oklahoma City last year.)