But a more accurate metric is something called a revenue passenger kilometer, or RPK. One passenger traveling one kilometer equals one RPK. In other words, flying a hundred people from Cape Town to London outscores flying them from Dallas to Phoenix. Except, running Dallas to Phoenix 12 times a day can make up the difference. Thus RPKs account for customer volume, frequency of flights and distances flown.

This kicks Southwest down to a more realistic seventh place. By the same token, Emirates is the planet’s eighth largest in RPKs, yet fails to crack the top 20 in passengers (still not “small presence” material by any stretch, but smaller). Little known China Southern is at No. 6 in total passengers, but 14th by RPKs. And so on.

The 20 largest airlines in the world, ranked by RPKs (excludes regional subsidiaries)

1. Continented (pending merger between United and Continental)
2. Delta Air Lines
3. American Airlines
4. Air France / KLM
5. Lufthansa
6. Southwest Airlines
7. British Airways
8. Emirates
9. US Airways
10. Cathay Pacific
11. Singapore Airlines
12. Japan Airlines (JAL)
13. Qantas
14. China Southern
15. Air Canada
16. Air China
17. All Nippon Airways (ANA)
18. Thai Airways
19. Ryanair
20. Korean Air

You’ll notice that Air France and KLM are counted together. I wish this weren’t so, but that’s the way the data is tracked. The two companies merged in 2004, but have kept separate operational structures, with independent fleets and employee groups.

You might be tempted to think of the biggest airline as the one with the most aircraft, but capacity differences make this reasoning specious. American Eagle, for instance, has more planes than JAL, Qantas or All Nippon, but is nowhere close when it comes to passengers or RPKs. For the record, Continented and Delta hold the top positions with about 750 jetliners each, followed by American with just over 600. Air France’s 260 (not including KLM) comprises the largest non-U.S. fleet, followed closely by Lufthansa and China Southern. FedEx, incidentally, has 340 jet freighters, and UPS 220. Obviously these totals are subject to frequent change as planes are bought, sold, mothballed and retired.

Is there a correlation between size and profitability? Not really. Going back to that “World Airline Report,” here were the top-10 best-performing airlines, measured in annual net profit:

1. Qantas
2. Lufthansa
3. Turkish Airlines
4. Singapore Airlines
5. LAN (Chile, Peru, Ecuador)
6. Emirates
7. Aeroflot
8. Southwest Airlines
9. Air New Zealand
10. COPA (Panama)

Plenty of stars on that list, but almost no stars and stripes. We’re used to this, sadly. Year after year, it seems, carriers outside the United States tend to be profitable while our own biggest airlines slip deeper and deeper into the red. Why is this? That’s an enormous question that we simply don’t have time or space to adequately answer. Competitive environment, state ownership and subsidies, and the price of labor all play a role.

Though not always in the ways, or to the extent, that people think. Take the second factor. Not all of those 10 carriers in the above list are privately run, bringing up the issue of governments that provide tax breaks, subsidies and other favors for airlines they sometimes own outright. There’s a widely held assumption that this is done excessively and unfairly, but in truth the degrees vary. For example, many EU and Asian carriers have been upset over the massive expansion of Emirates, which they attribute to coddling of the carrier by its owner, the government of the United Arab Emirates. Perhaps, though a pair of audits by two renowned investment houses concluded otherwise. “We could not find anything in Emirates’ accounts which indicated that the business is subsidized directly or indirectly or given undue preference,” said one representative, speaking in Air Transport World. People point out that Emirates pays no corporate income tax, but as the ATW feature noted, it also bears significant social costs by providing housing and education for thousands of expatriate employees.

Either way, we’re foolish to go searching overseas for answers. The problem isn’t between the U.S. airlines and those in other countries, it’s between the U.S. airlines themselves, operating in the most competitively cutthroat theater that exists, with the legacy majors under constant siege by nimble, low-cost opportunists like JetBlue and Southwest.

Meanwhile, neither size nor profitability is a firm indicator of customer satisfaction. Which are the best carriers, in terms of overall service?

Let’s see what SkyTrax says. SkyTrax is a prestigious air travel advisory group that ranks carriers on a scale of one to five stars. Currently only six airlines meet the group’s strict criteria for five-star status, awarded only to those “at the forefront of product and service delivery excellence, often setting trends to be followed by other airlines.” They are, alphabetically:

Asiana Airlines (Korea)
Cathay Pacific (Hong Kong)
Kingfisher Airlines (India)
Malaysia Airlines
Qatar Airways
Singapore Airlines

Dropping down a notch, 29 carriers manage to hit four-star status. This is where you’ll find most of the mainstay Asians and Europeans, plus a few surprises. The list includes Air France, Emirates, British Airways, Lufthansa, JAL, Korean, Qantas, Air New Zealand, Swiss, Thai, Turkish and South African Airways. The sole U.S. finisher is JetBlue.

The rest of the Americans are all in the three-star category, having achieved “a satisfactory standard of core product across most travel categories, but poor or less consistent standards of staff service/product quality in selected on board or airport features.” This is the biggest group by far. Delta, United, American, US Airways and Continental join the likes of Ethiopian Airlines, Aerolineas Argentinas, Pakistan International, Iberia and dozens of others. Southwest is here too.

It could be worse. Thankfully there are no Americans among the 25 or so names on the two-star list. Here you’ll find Cubana, Uzbekistan Airways, TAAG Angola and Biman Bangladesh. And Ryanair.

The one-star list contains but a solitary finisher, the mysterious Air Koryo of North Korea.

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Do you have questions for Salon’s aviation expert? Contact Patrick Smith through his Web site and look for answers in a future column.