JetBlue (JBLU) reported surprisingly positive third-quarter results, but the low-fare carrier said unit revenue growth slowed as the summer travel season concluded.

"This airline screams during the peaks," said Chief Financial Officer John Harvey, on a conference call. " But we're a discretionary airline or leisure airline by and large. We're working hard on the trough periods."

JetBlue shares rose sharply, trading at $9.71, up about 7%.

To spread demand, the airline continues to revise its route structure. JetBlue said Tuesday that it will discontinue flights to Columbus and Nashville in January. It plans more flights that bypass New York's congested Kennedy Airport, including flights to Florida, the Caribbean and northern South America from various cities.

Additionally, planned capacity growth will slow. The airline has 18 scheduled aircraft deliveries in 2008 but said it has agreed to sell two A320s and could sell more airplanes.

During the third quarter, net income was $23 million, or 12 cents a share. Analysts had estimated 7 cents. In the same quarter a year earlier, the airline lost $500,000. Revenue was $765 million, up 21.9%. Analysts had estimated $767 million.

Passenger revenue per available seat mile grew 9.1% to 8.52 cents. Load factor was 82%, up 1.6 points, on a capacity increase of 10.9%. On the expense side, cost per available seat mile, excluding fuel, rose 5.3%.

Looking ahead, the carrier said it expects passenger RASM to grow 2% to 4% in the fourth quarter and 5% to 7% for the year.

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