Texas International Airlines yesterday announced an experimental airline "seat sale" that will give travelers a chance to purchase tickets at discounts from 66 to 83 percent off current coach fares.

Unlike other airline tickets sold in the United States, the highly discounted tickets, once purchased, cannot be transferred to another person, reissued for another flight or returned for a refund. Tickets must also be purchased when the reservations are made -- at least 14 days before departure.

Having received almost instant approval of its plan from the Civil Aeronautics Board, the airline is now selling the tickets for travel beginning Sept. 3.

Washington-area travelers can take advantage of the fares on Texas International flights from Baltimore-Washington International Airport. From BWI, the special fare will be $59 to Dallas/Ft. Worth, Houston or and New Orleans, representing savings of 67 to 73 percent. These fares are considerably cheaper than going by bus. For instance, bus fare from Washington to Houston is $97.

As an example of the possible savings, a roundtrip ticket to Dallas using the special fare will be $118, compared with a current regular roundtrip air coach fare of about $438. Texas International's 50 percent-off "peanuts" fare, which will also continue to be available, costs $220 roundtrip.

About 50,000 seats a month on the airline's system, or about 10 percent of its total, will be available at the special fares, according to airline officials. The seats will be offered on 179 of its 278 daily flights at 28 of the 35 cities it serves.

The number of seats available on each flight at the discount varies, ranging from no fewer than 10 to as many as 50 or 60.

"These are seats that never sell," acording to Ron Woestemeyer, TI's vice president for marketing programs. "We believe that with the unprecedented deep discounts, we can tap a whole new market of potential air travelers, even during a period of the year when passenger traffic is traditionally soft and despite the recession."

Airline officials often speak of airline seats on given flights as perishable commodities; once the flight has taken off, a seat on it is either filled and produced revenue for the airline, or it is empty and it produces nothing. Yesterday, Woestemeyer said Texas International's seat sale is an attempt to make airline seats something akin to theater tickets: "Once you buy one, it's yours, whether you use it or not."

That's why the airlines can give the unprecedented discounts, he said. "We are taking the unsold seats we know we're going to have and selling them in advance," he said.

Besides the $59 pricetag on TI's longer-distance flights such as that from BWI to DFW, the Houston-based airline is also offering discounted fares of $19 for its short flights and $29 for its medium flights.

Woestemeyer said that the seat sale could become a permanent part of the airlines's array of discount fare offerings if passengers accept the non-traditional restrictions in return for extraordinary savings.