"Big news in big seats. Introducing a new way for business fliers to fly coast to coast" begins an airline advertisement in The Washington Post.

The enticements include wide seats, free drinks, entree choices, priority baggage handling and special check-in facilities.

Service and comfort. Those words are the main ingredients of the so-called "business class," an increasingly important market the airlines are courting. Even the names--Executive One, Ambassador Class, Club Class and Super Club Class--connote executive luxury.

Airlines are focusing more attention on the business sector--the frequent fliers are most often business travelers--as a steady, stable source of revenue.

Moreover, the demand is growing.

"Businessmen are interested in time and convenience," said Maurice Finkelstein, owner of the Enterprise World Travel agency. "The major carriers do everything they can to keep the business traveler."

Business class sections on transcontinental flights made their debut last October when World Airways launched its new "Executive One" service, and Trans World Airlines said it would follow with its own domestic business class.

TWA is expanding the Ambassador Class, catering primarily to business travelers, to transcontinental flights because this section remained 80 percent full last year, proving demand for such a service, said David Vens, TWA director of public relations.

Previously, business sections were offered by the major carriers for overseas flights.

Business class sections are, for the most part, like first class, and the section is generally located just behind first class seats. Passengers have special check-in facilities to speed up seating assignments and baggage handling. Drinks and headsets are free and the food is better than meals served in coach. More important to the business traveler are roomier seats and extra legroom. Furthermore, club memberships are available through various airlines which operate club facilities at airports.

As added amenities for the new business class services, TWA will offer an inflight telephone service (eleven other airlines have also signed up for telephone systems on board) and World provides an in-flight mailbox, toilet kits and stopovers at no extra charge for passengers enroute to certain destinations.

"People will pay for a larger seat and service," said TWA's Vens. "It's time to establish a product people will buy at fair price."

Recognizing the potential sales in a business class section, World Airways dropped its first class section in favor of "Executive One," a business class that still retains all the airline's first class services but at a much lower price. The airline found its business class section attracted significantly more passengers than the first-class service had.

The maverick airline that once bragged about its "no-frills" service for discount, cross-country passengers is now boasting of first class service at bargain rates.

"The only similarity between World's business class and the competition's is the name--the service resembles their first class and the price comes closer to their coach," said Edward J. Daly, president and chairman of World Airways.

Although limited to two airlines in the domestic market, business class sections are expected to catch on, airline representatives predict.

In fact, TWA would like its chief competitors, United Airlines and American Airlines, to offer business class sections as a means to end fare slashing and other gimmicks, and to emphasize service to compete with "discount" or "budget" airlines which don't have the capacity to match the major carriers.

"We tried to market ourself on fare alone, and you can't survive," Vens said, adding that airlines must "discipline" themselves in pricing.

Nevertheless, United and American, along with Pan American and Eastern airlines, have dropped round-trip coach prices on transcontinental routes to about $360 to $480.

TWA is now working on repricing its coast-to-coast fares, Vens said, adding that a one-way business class ticket to the West Coast is $340, only $15 more than coach. World offers its West Coast business class fare for $399 round trip.

And virtually every major airline has instituted a "frequent flier" bonus that allows a passenger to accumulate mileage credits toward a free ticket.

The "discount" or "budget" airlines are also aware that services directed towards the business traveler can be lucrative.

New York Air, set up to compete with Eastern Airlines' shuttle operation between Washington's National Airport and LaGuardia Airport in New York, recently flew its one millionth passenger.

Additionally, Midway, which flies between Washington and Chicago, gave business travelers who paid the regular fare a $60 dining credit redeemable at selected restaurants in either city.

Meanwhile, the changes in the industry from the time it was deregulated in 1978 to the more recent airline controllers strike have had an impact on business traveling.

According to Finkelstein, Washington businessmen are traveling less and consolidating trips because of flight cancelations and delays, price fluctuations and inconvenient flight schedules.

But he and other travel agents believe there is more travel per capita in the Washington metropolitan area than anywhere else.