Did you have a good summer? Alaska Airlines sure did.

Passenger traffic at Alaska Airlines soared 9.7% in June, July and August, according to a compilation of monthly data I put together. Alaska boosted its capacity by 6.1% in the three summer months and still managed to fill a higher percentage of its seats.

The smallest increase in passenger traffic this summer: US Airways at only 1.5%. US Airways was also the only major passenger airline to suffer a decline in its load factor – the percentage of seats filled.

Of course, what we don’t know from airline traffic reports is what people paid to sit in those flying seats. If airlines held out for higher prices, they can sometimes end up with fatter revenue and yet lighter loads. And carriers can rev up their traffic by slashing prices. So traffic gains or losses don’t always predict the bottom line.

But all indications so far have shown that prices were considerably higher this summer compared to last year. Fees have risen, too. And so with more people traveling and most of them paying a lot more, it looks like it was a very good summer indeed for airlines, even in the face of global economic weakness.

Traffic reports do verify for travelers what they most likely experienced at the airport. On the whole, flights were fuller this year. That may be hard to fathom when most every plane you get on is full. But on average, the nine major U.S. passenger airlines filled 86.4% of their seats in June, July and August combined, up from 85.5% last summer.

Major carriers increased their capacity, which is measured in “seat-miles” (one seat-mile is one seat flown one mile) by 2%. And their passenger traffic, measured in revenue-passenger miles (a passenger mile is one paying customer flown one mile), jumped 3%. That’s a good showing given the economy (and higher ticket prices). But some did a lot better than others.

JetBlue Airways was the most aggressive with a 7.1% increase in capacity this summer. That paid off with an 8.6% jump in passenger traffic for jetBlue.

Delta, American, United, Continental, Southwest and US Airways all increased their capacity this summer by 2.5% or less. Among those carriers, Southwest had the biggest traffic gain at 4.9%, followed by American’s 3%. Delta, United, Continental and US Airways all fell below the 3% average traffic gain.

In general, with the exception of Alaska, discount airlines grew more this summer, both in capacity and in passenger traffic. The gradual shift in market share for lower cost carriers continued. Another way to look at it: Smaller carriers with less international exposure performed better this summer.

Here’s a breakdown.

Airline               Traffic Change       Capacity Change   Load Factor

1. Delta                 1.9%                     0.8%                     87.5%
2. American          3.0%                     2.5%                     86.1%
3. United               2.7%                     1.5%                     87.3%
4. Continental       2.2%                     0.9%                     87.1%
5. Southwest         4.9%                     2.3%                     83.0%
6. US Airways        1.5%                     1.9%                     85.6%
7. JetBlue               8.6%                     7.1%                     85.6%
8. Alaska               9.7%                     6.1%                     85.5%
9. AirTran              3.7%                     2.7%                     86.5%

Notes: Figures from company traffic reports for June, July and August combined. Airlines ranked by size, based on passenger traffic.

Source WSJ   By Scott McCartney