Warren Buffett's Always Been Attracted to Airlines

Warren Buffett has dabbled in the airline industry throughout his career. He bought 10% of US Air 1, which was a preferred stock and didn't lose any money on it. But from there on out he's spoken about how tough it is to invest in airlines. Is it really a pricing thing? And if there's anything we can take away from it, some sort of potential red flags or a bunch of red flags, maybe, that we could use as we look at other companies for better returns.