In October, the Federal Aviation Administration certified Embraer’s first midsize jet, the Legacy 500, and the company says it expects to deliver as many as six of the airplanes by year’s end. The clean-sheet design features fly-by-wire controls, which enable the crew to maneuver the jet using computer signals instead of mechanical linkages. In the cabin, passengers find a space 6 feet tall and 6 feet 10 inches wide, with a flat floor and eight ergonomic seats that convert to fully flat berths. Optional divans…