UPDATE 1-Fronter Airlines posts quarterly loss on costs

(Adds analyst estimates, outlook)

NEW YORK, July 26 (Reuters) - Frontier Airlines Holdings Inc. FRNT.O said on Thursday it posted a quarterly loss, after a profit a year ago, burdened by higher fuel expenses and start-up costs related to low-cost unit Lynx Aviation.

Denver-based Frontier posted a fiscal first-quarter net loss of $3.5 million, or 10 cents per share, compared with a profit of $4 million, or 10 cents per share in the year-ago period.

Increased fuel expenses due to derivative losses, Lynx start-up costs, and a seat replacement project combined to lower earnings by 20 cents per share, the company said.

Excluding items, Frontier posted a profit of 10 cents per share, beating analysts expectation of 6 cents, according to Reuters Estimates.

Revenues rose to $344.8 million from $304.8 million as a 14 percent increase in mainline capacity offset a 1.1 percent decline in unit revenues.

Analysts expected it to post revenue of $343.5 million.

Looking ahead, Frontier forecast a profit per share of 5 cents to 10 cents for fiscal second quarter. Analysts expect the company to post a profit of 8 cents. (Reporting by Chris Reiter and Paritosh Bansal)