U.S. negotiators this week proposed "a fundamental revision" in the 28-year-old bilateral agreement that governs aviation services between the United States and Japan, Civil Aeronautics Board Chairman Marvin S. Cohen said yesterday.

In a speech to the International Aviation Club, Cohen said the United States took "new initiatives" during talks with the Japanese in Honolulu in the hopes of resolving the "20 years of ingrained disagreement" that have characterized the U.S. - Japan aviation relationship.

Cohen said the United States had proposed a comprehensive package that assures Japan of "full access to U.S. markets" by expanding the number of cities in the United States its airlines could serve and by offering Japan some expanded rights to fly passengers to the United States and "beyond."

At the same time, the package would guarantee U.S. airlines full access to Japan's airports, give them greater pricing flexibility and allow U.S. charters into Japan.

The Japanese have long contended that the rights granted under the current bilateral agreement are "imbalanced" in favor of the Americans. "We disagree with this contention," Cohen said, noting that Japan Air Lines carries about the same number of passengers and amount of cargo -- some say more -- than the four U.S. airlines with Japanese authority combined.

"But we recognize that Japan has genuine and deeply felt concerns about the perceived imbalance in route rights as stated in the current agreement," he said.

Cohen said he is "cautiously optimistic" about the discussions, which are set to resume sometime this spring after the Japanese have studied the U.S. proposal.

Although Cohen declined to be specific about the U.S. proposal, sources said it contained these elements:

Japan's right to fly to four more U.S. cities, three to be named in the agreement and one "rover" that Japan could pick at will. Although not disclosed, they could well include Seattle and Chicago, two cities JAL has wanted.

The right of Japan to pick a major U.S. city from which it can fly "beyond" to whatever destination it wants. Now, Japan has the right to fly to Europe from New York, but only if the plane stops in San Francisco first.

A more liberal pricing provision. Now, both Japan and the United States have to approve an airline's proposed fares, and the Japanese government is not considered favorably inclined to low fares.

A provision that will assure U.S. airlines the right to fly charters into Japan, with rules for prices and restrictions to be set in the country in which the charter originates.