Mesa Airlines, Inc. is an American regional airline based in Phoenix, Arizona. It is a FAA Part 121 certificated air carrier operating under air carrier certificate number MASA036A issued on June 29, 1979. It is a subsidiary of Mesa Air Group. It operates flights as American Eagle and United Express. It serves more than 180 markets in the Western Hemisphere. Mesa\'s safety record was noted as having the fewest incidents among domestic regional airlines in the Journal of Air Transportation.