Investing in airline industry stocks is a challenge. Airline companies generally have low profit margins, high debt loads and cyclical performance. The industry is very competitive in the U.S. and overseas, as too many airlines compete for too few travelers. After consumers and businesses reined in travel spending in 2008 and 2009, travelers are flying once again, which is good news for the airlines. Revenues at airlines in the U.S. are forecast to advance a whopping 17% in 2010, with another healthy increase in 2011. Profits of $3 billion are forecast for 2010 compared to an ugly deficit of...