You can set your Swiss watch to it: Year in and year out, Swiss International Air Lines—sometimes it just calls itself “Swiss”—emerges as the most profitable airline in the Lufthansa Group. It does better than Austrian Airlines, better than Brussels Airlines, better than Germanwings, better than British Midland (or did when it was still around) and better than the Lufthansa-branded airline itself. Not unlike the Swiss economy relative to the economies of Switzerland’s troubled neighbors, Swiss is a rare legacy airline that consistently thrives. Last year, in fact, its 7% operating margin was its best in three years and even…