Brazil airline Gol posts fifth loss in six quarters

* Third-quarter net loss of $150 million is smaller than year ago

* Operating loss deepens on fuel prices, weak demand

SAO PAULO Nov 14 (Reuters) - Brazilian airline Gol Linhas Aereas posted a third-quarter net loss of 309 million reais ($150 million) as softer domestic demand and high fuel prices led to a deeper operating loss.

Gol has reported a net loss in five of the past six quarters, including a 517 million reais loss in the third quarter of 2011.

The loss before interest and taxes widened to 201 million reais from 75 million reais a year earlier, according to a securities filing late on Tuesday.

Last quarter Gol said it expected a 2012 loss before interest and taxes, scrapping a prior forecast for a profit equal to between 4 percent and 7 percent of revenue.

A 26 percent increase in fuel costs and 62 percent rise in aircraft rental costs continued to erode profitability. But a more stable exchange rate led to just 6 million reais in currency-related losses on the company's debt, down from 476 million reais a year earlier.

A weaker currency still hurt Gol's operations as Brazil's real fell nearly 8 percent in the year through September, driving up the cost of dollar-denominated expenses such as leasing, fuel and maintenance.

Earnings before interest, taxes, depreciation, amortization and aircraft leasing fell 23 percent to 96 million reais.