With the help of two new American Boeing 737 passenger jets and a$14-million loan from the World Bank, operation "Destination Tanzania" aimed at attracting tourists back to this country has taken off and is flying well.

After a two-year lapse, the game parks and Indian Ocean beach hotels of Tanzania are crowded once again this wintr to the point where tourists have practically overwhelmed the country's still-limited capacity to handle such large numbers. Italians seem to be leading the European rediscovery of Tanzania as a winter tourist haven, but a few Americans can also be discerned in the crowds at hotels and airports here.

Tourism here virtually came to a standstill after the closing of the border with Kenya in February 1977, and the collapse of East Africa Airways serving those two countries and Uganda.

The effect to these two developments was to close off some of Africa's most renowned tourist sites and sights to the outside world. Tanzania boasts three spectaculars -- majestic snow-capped Mount Kilimanjaro, Africa's highest mountain; The Ngorongoro Crater, teeming with half-tamed wildlife of all sorts, and the Serengeti Park, rated among the best anywhere on the continent for game viewing.

It also has miles of empty, white sand beaches massaged by the warm waters of the Indian Ocean and a wide variety of other attractions ranging from East Africa's best wood sculptors, the Makonde, to the oldest slave town on the Indian Ocean at Bagmoyo.

For years, tourism in Tanzania was little more than a subsidiary business of Kenya's Nairobi-based agencies, which made part of their fortunes by taking visitors on package tours across the Kenyan border to visit Ngorongoro and Serengeti. But the tourists spent few days and little money here, leaving a bitter feeling about tourism among Tanzanian officials.

In addition, strong supporters of Tanzania's home-spun Socialist ethic argue that tourism would only corrupt the country's moral values, divert resources from development and enrich few at the expense of the poverty-stricken peasantry. As a result, lodges and hotels were allowed to run down and tourists were tolerated but hardly loved here.

Now, however, all such negative attitudes toward tourism have gone out the window, and the government has made a firm commitment to rehabilitating run-down park lodges and expanding hotel capacity, both in the capital and along the coastal beaches with the help of a World Bank loan.

Tanzanian tourism officials seem delighted with the results of their promotion campaign abroad to get European and American agencies to sell Tanzania as separate destination from Kenya or as part of a park-and-beach package including the Seychelles Island.

"It worked much better than we expected," said Albert Mikapagaro, acting director of marketing for the Tanzanian State Tourism Company. "We were able to convince tourists to come here after all."

He reported the game park lodges in the north were running at 80-percent capacity this winter and hotels on the coast at 90-to-95 percent. This compares to 1977 when the parks and beaches were practically deserted. In addition, the average length of stay for tourists has more than doubled from the 2.5 days prior to the closing of the border with Kenya, according to Mikapagaro.

The main problems Tanzania has had to overcome to launch its own tourism are access routes, an acute shortage of its own aircraft and higher costs than in neighboring Kenya because of the greater distances from European capitals and even within the country getting to the parks.

With the closure of the border with Kenya, European airlines were forced to choose between landing in Nairobi or Dar es Salaam, because Tanzania refused to allow any traffic between the two capitals. Most chose to maintain the capitals. Most chose to maintain the lucrative route to Nairobi, which is the main stopover and refueling point in Black africa for fligts to Sourth Africa.

But Tanzania did convince two European carriers, KIM and British Airways, and Ethiopian Airlines as well, to fly directly into the new international airport at the foot of Kilimanjaro serving the northern game parks. Tanzanian tourism officials are hoping Lufthansa will follow suit shortly, but Pan American, the only link to the United States, has refused, making it necessary for American visitors to transit through Europe.

There is also a problem for tourists coming from Europe on other airlines directly to Dar es Salaam. Until this month, Tanzania's own new airline had just four aircraft, two of them Boeing 737s leased on a parttime basis, to serve all domestic points and flights to four neighboring countries.

Air Tanzania service between the capital and Kilimanjaro has been most notable for its total unreliability. Thus many tourists have found themselves stuck in the northern town of Arusha, the jump-off point for the parks, or forced to make an eight-hour overland trip to catch their flights back to Europe or onward to the Seychelles.

But with a $25-million loan from Japanese banks, Air Tanzania is now getting two of its own Boeing 737s to improve its internal service. This should resolve the crisis of getting from the northern parks to the getting from the problem of higher cost remains, however.Hotel rooms in Tanzania run $7 to $15 less than in Kenya. But ground transportation is far more expensive and flights to Dar es Salaam are higher than to Nairobi.

This differential is unlikely to change. But as one enthusiastic Western embassy official just back from the parks remarked: "They have a helluva product to sell."