Eastern Airlines yesterday brought its new airplane to Washington National Airport, and it appeared to be as quiet, as clean, as smooth, and as comfortable inside as promised in the publicity that preceded it.

The European-built A300 was the largest commercial jet ever to land at the airport, but may become a familiar sight if the Federal Aviation Administration clears if for use here. The chances are good.

"One of the major goals of our proposed policy for the operation of National and Dulles Airport is noise reduction." FAA Administrator Langhorne Bond said at a briefing yesterday prior to a noise monitoring test from the run-aways and a demonstration flight on the twin-engine jet.

Bond said the A300 was the "quietest" jet plane ever to land at National a statement supported by the results of the tests. On take-off, the A300 scored a 96 decibel rating after a half-dozen planes, mostly Boeing 727s, took off, routinely scoring 106 and 107. Because of the logarithmic scale, the difference in the readings means half as much noise from the A300 as from the 727s, a difference that was perceptible to the listener. "Jeez, that's quiet," exclaimed Frank Borman. Eastern's chairman and president said on the edge of the runway during the test. "How about that."

Bond, too, was impressed. "People have associated big planes with noise, but it's not true," he said. The new technology has gone into making the big planes more quiet and easier to operate, as well as more fuel efficient than the smaller jets now in operation, he noted. The A300 needs less runway to take off and land as well, he pointed out.

If cleared, which is expected after public hearings and a series of proving flights, Bond said use of the A300 - with its larger seating capacity - could result in a reduced number of total flights into the busy airport. Borman confirmed that if approved, Eastern plans to use the plane to cut down on some of the 150 extra sections of the Washington-New York shuttle it runs every week.

Eastern just last week signed a contract to acquire 23 of the widebody planes produced by Airbus Industrie, a consortium of European firms. In welcoming government officials, civic leaders, and representatives of the travel industry to the briefing yesterday, Borman was quick to point out that although the plane is European-built, more than 33 per cent of its components come from U.S. suppliers, including engines from General Electric Co., and that over the life of the plane, that will increase to 50 per cent. In addition, Borman noted that fuel savings available with the plane would enable Eastern to cut down on the fuel it must buy from overseas. "In no way can you attack this program as damaging to American balance of trade," he said.

Eastern bought the plane because it is "the finest machine available in its category in the world today," Borman said.

Civil Aeronautics Board Chairman Alfred E. Kahn confessed that he didn't know much about airplanes; "to me, they're all marginal costs with wings," the economist turned-regulator said. But he congratulated Eastern on getting his message: that increased competition is in the air industry's future and they ought to be seeking to be as economic and efficient as possible.

"This is a precise example of the kind of enterprise that will be the clue to prosperity . . . in the competitive era that lies ashead," Kahn said.

After the briefing and noise tests, the plane was loaded and passengers were taken on a nearly-90 minute ride in the clear skies to charlottesville, past Richmond, to Yorktown and Jamestown and north again.

The planes have 229 seats, with two aisles: there are two seats at the windows and four seats in across in the center section. Later planes to be delivered will have 244 seats.

Among the passengers was Allegheny Airlines President Edwin Colodny; Alleghney is considering buying two A300s if it gets a new route from Pittsburgh to the West Coast, and Colodny had never been on one. He was impressed too.