The numbers are in. According to the annual Airline Quality Ratings, Motley Fool Stock Advisor selection JetBlue (NASDAQ:JBLU) is once again the highest-quality U.S. carrier. It's the third year in a row that the upstart airline has topped the list. In fact, it's been top dog since first being included in the rankings in 2003.

Time to celebrate, right? Not so fast. There's much more here than meets the eye, even if the results look more impressive when you consider the performance of rest of the top ten:

Company

2005 rank

2004 rank

JetBlue

1

1

AirTran (NYSE:AAI)

2

2

Independence Air*

3

N/A

Southwest (NYSE:LUV)

4

3

United (NASDAQ:UAUA)

5

4

America West**

6

6

Northwest

7

7

Continental (NYSE:CAL)

8

9

Alaska (NYSE:ALK)

9

5

American (NYSE:AMR)

10

8
* No longer operating
** Now merged with U.S. Airways
Sources: USA Today and AQR

Ouch. Only one improved in the standings, and that was legacy carrier Continental. Alaska's rating plunged. Even Southwest got nicked. If you didn't look any deeper, you might conclude that JetBlue shares were a screaming buy -- a great company in a lousy industry.

Maybe, but a quick read of the full PDF report (which you can download here) reveals that, among other things, JetBlue's on-time performance was among the worst of those rated, dropping more than 10 percentage points from the year before. Moreover, JetBlue saw increases in its rate of customer complaints and mishandled baggage.

To be fair, JetBlue's ratings were still ahead of the industry average and the bulk of competitors in both of those categories, and its mark in denying passengers boarding -- which sometimes occurs when a flight is oversold -- was positively pristine. Nevertheless, the stats make it clear that the upstart carrier isn't doing as well as it once was. While it's impossible to predict an ongoing descent, I'd hardly be surprised if turbulence persists until management finds a way to reverse course.

We're taxiing toward related Foolishness:

JetBlue is a Motley Fool Stock Advisor selection. Ask for us anall-access passto all of the stocks that are helping David and Tom Gardner beat the S&P 500 by more than 30 percentage points each. It'sfree for 30 days.

Fool contributor Tim Beyers didn't own shares in any of the companies mentioned in this story at the time of publication, but he has relatives who are retired from United Airlines. You can find out what is in his portfolio by checking Tim's Fool profile . The Motley Fool has an ironclad disclosure policy .