U.S. and Japanese negotiators began meeting in Honolulu yesterday in the hopes of resolving some issues that have made the aviation relationship between the two allies "somewhat contentious" for years, in the words of one government source.

One of the first things on the agenda during the five-day talks is the right of Pan American World Airways to stop in Tokyo on its way to China.

Pan Am had planned to begin its three weekly flights to China early last month but delayed the start-up date until Jan. 28 at the request of the U.S. government when the Japanese indicated displeasure with the plan.

The problem Pan Am has confronted in seeking to start its newly awarded China route with the stop in Tokyo is considered by U.S. officials to be part of a pattern of problems that U.S. airlines all too often encounter when seeking to use rights the U.S. government says they have under the U.S.-Japanese bilateral agreement.

U.S. officials contend that Pan Am's right to stop in Tokyo is clear and not negotiable. The U.S.-Japan bilateral agreement says clearly that U.S.-designated airlines have the right to fly from U.S. points to Tokyo "and beyond," they say. Specific cities or nations are not listed; just the word "beyond" is used, they point out.

However, some Japanese officials say there is another interpretation of the bilateral pact. A spokesman for Japan Air Lines, Japan's only international airline, points out that the U.S.-Japan bilateral agreement was signed in 1952, three years after China was essentially closed to the rest of the world. Since a U.S. airline couldn't go to China at that time, China cannot be considered included in the "beyond" rights the agreement grants, according to this intrepretation, the spokesman said.

These kinds of difficulties have been creeping up for some time, U.S. government and airline sources say, perhaps because of Japan's general view that the bilateral agreement is "umbalanced" in favor of the United States. "The Japanese view has been that the aviation relations between the two countries -- if one takes a look at the provisions of the agreement -- are not equal," Hiroshi Fukuda, economic counsellor at the Japanese Embassy, explained.

"We take the view that the provisions in the agreement provide unequal opportunities," Fukuda said. He noted that the agreement allows U.S. airlines to pick up passengers in Japan and fly "beyond" to almost anywhere, while the Japanese carrier has only one "beyond" flight designation -- through the West Coast to New York and beyond to Europe.

Another way in which Japan thinks the agreement is out of balance is in the number of cities each nation's airlines can serve. JAL can fly to seven U.S. cities while U.S. airlines can fly to Japan from about 20 U.S. cities.

U.S. sources see the agreement and its provisions in another light."They can serve more places here than we can serve there, so what do you consider balance?" one government source asks. While JAO serves Honolulu, Los Angeles, San Francisco, New York and Anchorage, U.S. airlines can serve Tokyo and Osaka. While the United States allows Japanese charters to land here -- about 300 Japanese charters flew here last year -- the Japanese severely restrict the ability of U.S. airlines to fly charters there. Last year, U.S. airlines flew 10 charters to Japan.

In addition, U.S. sources point out that JAL carries more passengers between the two countries than one of the U.S. airlines. Besides Pan Am, Northwest Orient Airlines flies a regularly scheduled service, Continental Airlines flies one route and Flying Tigers has cargo service in Japan. A lot of JAL's passengers have been picked up by JAL "beyond" Japan in the United States, they say.

"A major issue is that we can't really serve all the points we have in Japan," one official said. "Constraints are attributed to lack of fuel or environmental concerns or slots at airports . . . so one of our concerns is whether we can use the rights we can use rights we legally have."

The talks that began yesterday are being billed as "informal" but both sides expressed hope that they will be a useful beginning in sorting out some complicated, continuing problems. "We would like to develop some changes to the agreement that would make us content and would make them content," said B. Boyd Hight, deputy assistant secretary of State for transportation and telecommunications, one of the members of the U.S. delegation.