"Here a durable competitive advantage has proven elusive ever since the days of the Wright Brothers. Indeed, if a farsighted capitalist had been present at Kitty Hawk, he would have done his successors a huge favor by shooting Orville down." – Warren Buffet, who invested in US Airways in the early '90s, on airlines in 2008
It's a really profitable industry these days. Low oil prices reduce costs. Plus, ticket prices haven't gone down because routes are consolidated to reduce competition between airlines.