Each time a commercial aircraft touches down at Salt Lake International Airport, it can be viewed as pennies - or dollars - from heaven.

On the wings of planes taxiing to the airport's main terminal ride millions in revenues, thousands of jobs and some of the keys leading to the successful economic development of the city and the rest of Utah.Salt Lake's airport ushers 10 million passengers yearly into the state and an estimated $500 million annually into Utah's economy, both conservative estimates, says Louis E. Miller, Salt Lake director of airports.

What's more, projected growth patterns at the airport show the number of enplaned passengers could balloon 100 percent by the year 2006, bringing a need for another runway, more parking space and other airport additions.

That forecasted growth, together with the soaring expansion the airport has already seen, translates into a supersonic economic development tool for the city and the state, Miller said.

"When you talk about economic development, you talk about jobs, that's the most important thing," Miller said from his airport office, tightly sealed from the roar of jet engines outside.

Numbers of air travelers at the airport will double by the turn of the century, according to growth projections. And to meet the needs of twice as many skiers, tourists and businessmen, officials recently unveiled an ambitious $600 million master plan.

The first phase of the plan, from 1988 to 1991, lays the groundwork for $28.9 million in airfield improvements, including modification of existing runways and a new high-speed taxiway, Miller said.

The main terminal will also be expanded and renovated to the tune of $7.2 million to accommodate more ticketing services, and terminal two will be expanded to house a larger baggage claim area at $14.7 million. A $30 million parking project will be constructed to meet parking projections for the next seven years.

Phase Two calls for $56 million in other terminal expansion and completion of a new runway costing up to $75 million. Miller said the new runway will increase the airport's traffic load and keep flight delays in check.

The Federal Aviation Administration's on-time performance record from April through August listed Salt Lake International at the top (figures for recent months are unavailable).

"If we don't have a new runway in place by 1995, we will no longer enjoy that reputation," Miller said.

The airport can't grow without confronting some barriers. Several environmental issues must be dealt with, like the relocation and mitigation of a vast fresh-water wetland between the airport and the shores of the Great Salt Lake, Miller said.

And the city's northwest quadrant, predicted to grow to a population of 65,000 in the coming decades, is another force the airport must contend with. Residential areas are obviously not compatible with an airport, evidenced by Miller spending $6 million buying out homeowners within the airport's noise zone.

As the northwest quadrant grows, zoning must be properly placed to restrict residential development near the airport where industrial development would be more compatible.

In the past seven years, the number of jobs created by Western Airlines and then Delta Air linesfollowing its acquisition of Western in April 1987 has grown by a factor of 11, Miller said. Much of that growth can be attributed to Western's and then Delta's decision to make Salt Lake International a hub operation.

Western employed 350 people in 1981 and 2,400 in 1985, and Delta employed 4,000 in 1988, Miller said, the largest number of employees among the 5,618 people working at the airport. Those figures don't include the hundreds indirectly employed pounding nails and moving earth for the $45 million in construction projects under way this year.

Miller estimated the impact from investments in buildings, improvements, salaries, wages and earnings tallies $312.3 million, up from $227.4 million in 1985.

The impressive numbers come from an effort by Miller and the Airport Authority, the board directing airport operations, to attract companies to the airport's 7,300-acre site.

`We'll do anything they need," Miller said, from cutting a financing deal to building an 88,000- square-foot marketing, reservations and training center for Delta in less than six months.

The plan cost taxpayers nothing because the airport issued $22 million in airport facilities revenue bonds, which can be paid back with airport-generated revenues.

The new reservation center sweetened the pot and helped to persuade Delta to establish its hub in the city and, perhaps more importantly, the deal was cut without dipping into the taxpayer's pocket.

"There are not taxpayers' dollars in any way, shape or form that pay costs at the airport," Miller said.

And two years ago Miller finished negotiations with McDonnell Douglas Corp., which located its fuselage panel manufacturing plant in a 180,000-square-foot facility that employs 189.

The deal the airport arranged with McDonnell Douglas gives them an option on 76 more acres, some of which are adjacent to runway space permitting them to expand their facilities.

Salt Lake Councilwoman Florence Bittner, who represents the city's northwest quadrant, where the airport makes its home, says there are "exciting prospects" for other aerospace industry to locate near the airport.

The airport sports acreage fronting on runways, a necessary commodity for aircraft manufacturers who, if they are to build entire aircraft, need runways to fly their craft to buyers, Miller said.

Miller has numerous statistics documenting the direct economic impact the airport has on the city and state. But kudos from Utah leaders reflect the more intangible value of the airport.

"In a lot of ways, the airport is our second arena," Utah Jazz Coach Frank Layden said.

"The Jazz depend greatly on the airport and the airlines that take us on at least 60 road trips each year, plus hundreds of other professional and personal jaunts," he said.

Tourism benefits tremendously from the airport. Utah's ski industry depends greatly on easy transportation access to the "greatest snow on earth."

"One does not make the decision to spend over $150 million on a resort without thoroughly analyzing the air transportation system," Snowbird Resort owner Dick Bass said.

Salt Lake International Airport is a "truly outstanding airport withing only 31 miles to some of the greatest skiing in the world," he said.