Representatives of airlines operating at Washington's National Airport told the Department of Transportation yesterday that its proposed airport policy won't accomplish its two primary goals: reducing noise and congestion at National and shifting more air service to Dulles International Airport.

Meanwhile, Civil Aeronautics Board Chairman Marvin S. Cohen canceled his scheduled testimony -- expected to be critical of the policy -- after indications from Transportation Secretary Drew Lewis and Federal Aviation Administrator J. Lynn Helms that the CAB would be asked to help DOT formulate its final airports policy. Cohen and other members of the CAB have been quite vocal about their concerns that new airlines be assured of access to the nation's airports, in keeping with the pro-competition goals of the Airline Deregulation Act.

In the second of two days of hearings on the proposed policy, fir instance, Henry Hill, president of Altair Airlines, said proposed reductions of flights at National Airport could return several routes, which now have competitive services and lower fares, to monopoly status.

If the proposed policy is adopted, the president of Piedmont Aviation predicted, "people living near the airport two months later will have to admit there is no noticeable difference in the amount of noise they perceive." William R. Howard said Piedmont, the third largest operator at National generally serving cities within 300 miles, has no objections to noise limitations. But he contended that the policy's provisions authorizing flights of up to 1,000 miles and unlimited extra sections would serve to undermine the policy's goals. "The noise to a listener on the ground is no different from an extra section flight than it is from a scheduled flight," he said.

James P. Bass, vice president of government affairs of American Airlines, was upset about the 1,000-mile rule too, but for a different reason. He said it discriminates against Dallas/Ft. Worth, American's major hub, which is 1,192 miles from National. Although he said American prefers no mileage limit, he said the "only equitable way would be to shrink the existing perimeter to 500 miles" with no exceptions from the current 650-mile limit, with its seven-city exception. "Most major carriers would be put on equal footing," he said.

Benjamin G. Griggs Jr., vice president of Northwest Airlines, questioned what he called the "erroneous assumptions" of the policy, including the assumption that Dulles is equal to or an alternative to National in terms of economics, dollar cost of facilities and access, passenger convenience and public acceptance. "Dulles is not competitive to National," Griggs said. "The public has shown this by overwhelming choice when comparable services have been offered." As examples, he cited former Northwest flights to Minneapolis/St. Paul and Detroit and its current service to Boston.

Speaking for 13 major airlines, Norman J. Philion, executive vice president of the Air Transport Association, criticized DOT's plan to make obsolete at National in 1986 virtually all of the jet aircraft currently operating there. Philion said the noise limitations are unrealistic, conflict with congressionally prescribed nationwide compliance schedules, and contravene the intent of Congress in deregulating the airline industry to promote new entry and competition.