Southwest Airlines launched a fare sale Tuesday with deep discounts on flights nationwide that one travel expert called “truly unusual.”

The Dallas-based Southwest put fares on sale early Tuesday for the fifth time this year, said Rick Seaney, chief executive of, a Dallas-based online travel firm that monitors airline ticket prices.

It’s the latest sign that demand for airline travel has been deteriorating as the recession widens.

“It’s the first time we’ve ever done this,” said Brad Hawkins, a Southwest spokesman.

“We’ve been saying all year that customers are traveling when the deal is right for them,” he added. “This opportunity opens up a whole range of dates and times to start dreaming of warmer days.”

“No one can say Southwest doesn’t move fast in trying times,” Seaney said.

The sale is notable, Seaney said, for several reasons:

It includes so-called “Click ‘n Save” promotional fares that are usually reserved for target cities, but in this case are available nationwide.

It is the airline’s first sale of the year to include cities in Florida, which suggests that leisure travel to beach destinations is slipping.

The sale’s travel dates extend through late June, a time when travelers are traditionally paying a premium, given the summer travel season. That indicates that Southwest is trying to convince consumers to book their tickets early.

Round-trip prices have dropped an average of $70 for 1,000 routes, Seaney said.