JetBlue ( JBLU) lost $8 million in the first quarter and said it will slow capacity growth when the summer travel season ends. The loss was equal to 4 cents a share, 3 cents better than what analysts had estimated. Revenue rose 34.2% to $816 million and exceeded the consensus forecast of $786 million. In the same quarter a year earlier, the carrier lost $22 million, or 12 cents a share. "We continue to see healthy demand throughout our network, and we are encouraged with the industry's more disciplined approach to capacity," said CEO Dave Barger, in a prepared statement. "However, JetBlue is not immune to the unprecedented rise in fuel prices, and we are taking steps to respond to this environment." Shares of JetBlue were up 3% early Tuesday. Barger said 2008 capacity will now grow by 3% to 5%. Additionally, the carrier said that starting June 1, it will join in an industry trend, charging $20 for a second checked bag. For the quarter, passenger revenue per available seat mile grew by 16.5%, as yield rose 20.2%. Capacity increased by 13.9%, while load factor declined by 2.4 points to 78.2%. On the expense side, cost per available seat mile grew by 12.8%. Excluding fuel, CASM decreased by 0.2% to 5.84 cents. Looking ahead, JetBlue said it expects passenger RASM to rise by 8% to 10% this year, while CASM, excluding fuel, will grow by 6% to 8%. During the second quarter, the carrier's pretax margin will be between negative 3% and negative 1%. This is the second busy week for quarterly results from the airline sector. Also Tuesday, AirTran ( AAI) had a wider-than-expected loss and said it will slow capacity growth. UAL ( UAUA), the owner of United, missed analysts' bottom-line expectations. Later this week, Delta ( DAL) and Northwest ( NWA), who plan to merge, will post their numbers. Continental ( CAL), Southwest ( LUV) and AMR ( AMR), the parent of American Airlines, reported last week.