In a major departure from previous policy, Taiwan today authorized a meeting between officials of its national airline and the national airline of China to discuss the return to Taiwan of a cargo plane and crew members now stranded on the mainland.

It would be the first open contact between representatives of government organizations from Taiwan and China in nearly four decades. No date has been set for the talks.

Long estranged from the mainland by differences of ideology and a bitter past history, the Nationalist government on Taiwan has in recent years repeatedly rejected Peking's overtures to negotiate or simply to trade and exchange mail. The island has pursued a "three no's" policy -- no contact, no compromise, and no negotiations with Peking.

Today, to the surprise of some diplomats here, Taiwan's China Airlines announced that it had sent a message to Peking through a third party stating its willingness to meet with mainland airline officials in Hong Kong to negotiate the return of crew members, cargo, and the Boeing 747 that a defecting Taiwan pilot flew into the Chinese city of Guangzhou on May 3. Taiwan proposed Hong Kong as the location for the talks.

In a statement issued in Taipei, the capital of Taiwan, Taiwan's flagship carrier said it asked Hong Kong's Cathay Pacific airline to relay the message. The Civil Aviation Administration of China has not made known its response, but Peking was believed likely to accept such a meeting.

Diplomats said it was not clear whether the meeting, if it materializes, would lead to broader contacts or a further lowering of tensions between the two sides.

"The significance over time will be whether Taiwan opens the door a crack or whether it opens it a crack and then slams it shut again," said one western diplomat.

Taiwan long has been the leading unresolved issue between China and the United States.

Taiwan still maintains that the Communist government on the mainland is not legitimate. Peking has long regarded Nationalist-ruled Taiwan as a breakaway province.

When pilot Wang Xijue flew to China 10 days ago, China treated it as a major event. In the past, defectors usually have gone the other way, from China to Taiwan. Wang said he wanted to be reunited with family members on the mainland. Wang's wife and children in Taiwan have expressed doubt that the pilot flew to the mainland voluntarily.

The two other crew members, copilot Dong Guangxing and mechanic Qiu Mingzhi, have said they want to return to Taiwan.

At one point, it appeared that China would hold the two crew members as hostages in an attempt to force Taiwan into negotiations.

But China dropped a demand that Taiwan send a representative to Peking and said it would agree to meet at another location. It said such talks would be of a business nature, with "no political issues involved."

Echoing Peking's statement, the Taiwanese airline in its statement today said the talks would be of a "business type between two civil airlines."

Taiwan had said earlier that China ought to send back the Boeing 747, the cargo, and all three crewmen.

It was not immediately clear to diplomats here why Taiwan agreed to talks.

A combination of factors, including the high value of the plane, may have been involved.

"When you've got a $62 million airplane, you've got a pretty big bargaining chip," said a diplomat in Peking.

China's senior leader, Deng Xiaoping, began several years ago to offer Taiwan a "one country, two systems" formula, such as will apply to Hong Kong in 1997. Peking officials say that this would allow Taiwan to reunite with the mainland while maintaining its army and its own system of government. Taiwan has rejected the offer as "sugar-coated poison."

Meanwhile, unofficial contacts have increased. Fishermen from Taiwan stop to rest and refuel along the coast of China's Fujian Province. Two-way trade between Taiwan and the mainland, most of it going through Hong Kong, is believed to have reached a value of more than $1 billion in 1985, double the previous year's figure, according to Chinese press reports.