Continental Airlines ( CAL) shares fell 3.6% after the carrier said revenue trends were weak for February, but analysts said the disappointing results didn't represent an industrywide trend.

Continental said February traffic, as measured in revenue passenger miles, rose 13.9% year-over-year, while capacity, as measured in available seat miles, increased 11.7% year-over-year. With revenue rising faster than supply, the carrier filled 70.2% of the seats on its planes, up from 68.9% a year ago.

But while passengers are filling Continental flights, they're paying less to do so, partly because of deep discounts to drive demand during a seasonally weak February. The company said that revenue per available seat mile, a key industry metric called RASM, fell between 2.5% and 3.5% during February, snapping a nine-month streak of RASM growth.

"February year-over-year RASM decline was partly attributable to Continental's strong performance relative to the industry during February last year, and the poor performance this year of the very competitive transcontinental markets, where RASM declined an estimated 25% to 30% as compared to February of last year," the company said in a statement.

In reaction to the weak RASM trends at Continental, Wall Street analysts made a number of negative comments about the carrier, saying the RASM drop was more than expected. Shares of Continental fell 56 cents to $14.91.

"We had estimated that Continental's February unit revenue would be, at best, flat versus a year ago so the results are a modest disappointment," said Michael Linenberg, airline analyst at Merrill Lynch. "However, it is our impression that some of the Street estimates may have been as high as a 3% gain."

But as with January, when Continental's slight RASM growth lagged peers, analysts said the carrier's results do not represent the entire industry, just increased competition on lucrative transcontinental routes the carrier serves. Bear Stearns expects other carriers to show RASM growth in February, but Continental is the only company to announce monthly RASM trends.

American Airlines parent AMR ( AMR) announced results that may be more representative of the industry as a whole. The carrier said February traffic increased 12.2% against a capacity increase of 11.9%, boosting load factor, or the percentage of seats filled on every flight, to 68.9% from 68.7% a year ago.

In reaction to American's February performance, Prudential Equity Group boosted earnings estimates on the company, raising first-quarter estimates to a loss of 44 cents a share from a loss of 59 cents a share. In the second quarter, Prudential analyst Daniel Hemme said he expects the carrier to earn 59 cents a share, up from a profit of 37 cents a share.

"After months of sluggish results, we view the strong report as a likely inflection point. With anticipated seasonal improvements and easy comparisons, we believe this strong trend should continue," said Hemme in a research note.

Despite the positive comment, American shares fell 33 cents, or 2.1%, to $15.45.

American and Continental saw international performance snap back from depressed levels a year ago, when results were weak due to fears about the war in Iraq. American's international traffic rose 17.4%, which lags a capacity increase of 19.8% and gave the carrier a load factor of 68.8% in February, down from last year. Continental's international performance was stronger, with traffic up 17.8% against a capacity increase of 11.4%, allowing the carrier to boost load factor to 69.5% from 65.8% last year.

Elsewhere, AirTran ( AAI) provided investors with a look at February results for low-cost carriers. The company announced February traffic increased 28.7% against a capacity increase of 27.8%, boosting load factor to 66.7% from 66.2% a year ago.

ExpressJet ( XJT), a regional carrier that flies for Continental as "Continental Express," announced that traffic increased 47% against a capacity increase of 44.8%, boosting load factor to 63.1% from 62.2%.

Shares of AirTran fell 13 cents, or 1%, to $12.62, while ExpressJet dropped 33 cents, or 2.4%, to $13.45.