The Air Force made it official yesterday.

It said the tiny North Dakota town of Fortuna, population 183 in 1970, will not get that $40 million to $60 million ground station for the Air Force's Navstar satellite system any time soon, if at all.

The town has been counting on getting the site, as the Air Force promised last year.

Sen. Milton R. Young of North Dakota, ranking Republican on the Senate Appropriations Committee, which helps determine how much money the Pentagon gets each year, has been championing Fortuna's cause.

Also, Gen. David C. Jones, chairman of the Joint Chiefs of Staff, told The Washington Post that he took a proper but direct interest in the site selection to make sure Fortuna got a fair shake. Jones is from North Dakota.

Jones said that in response to inquiries last year from fellow North Dakotans, he asked subordinates in the Air Force bureaucracy about Fortuna's prospects for getting the Navstar ground station. He was Air Force chief of staff at the time.

Acknowledging that his interest may have been "misinterpreted" by some in the bureuacracy, Jones said he did nothing to influence the selection. The Air Force, in announcing last year that Fortuna had won the plum, said the town's northern location would enable the ground station to stay in touch with Navstar navigation satellites a larger percentage of the time than competing sites.

But when Pentagon career bureaucrats got a look at Air Force plans for Fortuna, they complained it was the least desirable site from a number of standpoints, including bad weather, lack of skilled manpower and high costs.

Such claims gave influential people in both the Pentagon and Congress second thoughts about building in Fortuna. However, the Air Force refused for weeks to acknowledge this, reportedly because its leaders wanted to soften the bad news in telling Young and other North Dakotans.

Yesterday, after coordinating the response with Gerald P. Dinneen, a research deputy to Defense Secretary Harold Brown, the Air Force formally acknowledged that construction plans for Fortuna were being postponed as The Washington Post had reported earlier.

Instead of going ahead in Fortuna as planned, said the Air Force, construction will be put off until "at least 1983."

The cheaper alternative of using part of existing facilities at Vandenberg Air Force Base in California for Navstar will be studied in the meantime, the Air Force said.