Jan. 13--Worried about the effect of economic pressures on travel, the major airlines have unleashed a slew of unusually steep fare sales in recent days, travel experts say.

Cheap airfares are typical this time of year, which is traditionally the slowest period for travel. But many carriers have slashed prices on tickets for flights in the spring and even early summer.

"The travel period is really extended this year," said Rick Seaney, chief executive of Dallas-based FareCompare.com, which monitors airline ticket prices.

The discounts on spring travel suggest that the major airlines are unsure how strong bookings will be, given the economy's weakness.

Last January, fare sales typically covered travel only through March, he said. "But this year, we're seeing them go out to the end of April, and some are even sneaking into June."

For example, on Monday, Fort Worth-based American Airlines slashed prices to many international destinations, including flights to South America that depart in June.