I've made the comment before that the American airline industry may be the very worst business around. Participants will price-cut their way into oblivion, extort employees with the threat of bankruptcy, and set up a system that treats customers more like cattle than people. No great wonder, then, that so many have gone belly-up.

That's not quite the case outside the U.S., though. As British Airways (NYSE:BAB) demonstrated again on Friday, it actually is possible to run a profitable full-service airline. Of course, with about two-thirds of BA's pre-tax earnings coming from lucrative routes to the U.S., it's not really a fair apples-to-apples comparison with its domestic U.S. brethren.

In any case, revenue was up a bit more than 8% for the quarter as passenger traffic remained reasonably good. Higher fuel costs bit into profitability, though, and the operating margin declined slightly as operating profits rose more than 6%. Although reported profits dropped from the year-ago period, that was largely due to the absence of a gain on the sale of an investment in the Australian airline QANTAS.

Not only was BA profitable again this quarter, but the company continued to grow cash flow faster than both operating earnings and revenue. Six-month operating cash flow was up more than 9%, while free cash flow grew 11%. Assuming no major changes for the worse in the global economy or fuel prices, cash flow trends should continue to be positive. Not only is the new CEO looking to cut upwards of $500 million in costs, but the company is not scheduled to add any new aircraft until 2007.

BA is a profitable, growing airline trading at about 10 times earnings -- a fairly attractive valuation compared to other profitable carriers like Southwest (NYSE:LUV), Ryanair (NASDAQ:RYAAY), and Air France KLM (NYSE:AKH). While the company will continue to face competition from low-cost start-ups, BA has already had to deal with high-end rivals like Virgin and American competitors like Continental (NYSE:CAL). Though the notion of investing in an airline still makes me wince, there may yet be an opportunity here for investors.

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Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares).