United Airlines last month tested a new satellite-based communications system for transoceanic flights that could carve a larger role in the airline industry for Arinc Inc. of Annapolis.

The new system, dubbed Globalink, connects jetliners and ground crews via International Maritime Satellites, with electronic data replacing voice transmissions by radio, the technology airlines have been using for the past several decades.

The potential implications of the technology are broad, both for air travel and Arinc, a joint venture of several airlines with 1,600 employees.

United plans to install the system in three of its 747-400 aircraft by the end of the year and in the rest of the long-range aircraft by mid-1991.

American Airlines has ordered the Arinc communications system for its next batch of Boeing 767s, due for delivery next September, and is considering installing the gear in 767s, 747s and transoceanic DC-10s that it already has in service. Northwest Airlines is also beginning to equip some aircraft with the technology.

"Our projection is that by the end of 1995 there would be 500 commercial aircraft with the capability," said Jeff McKnight, Arinc's vice president for marketing and strategic planning.

Paul Ryan, a spokesman for American Airlines, was more optimistic. "I think all international carriers will go to this by 1995 and no later than 1998," he said.

For now, the satellite communications system will supplement voice communications. However, said United spokeswoman Susan Dornacker, "It has the potential to replace voice communications."

The system's most significant application is tracking airliners on transoceanic flights. The position reports it automatically transmits via satellite at regular intervals appear on computer screens on the ground.

While the traditional voice systems are subject to static and other interference, the satellite system provides guaranteed and immediate transmission from the ground to the cockpit as air traffic controllers transmit necessary course changes to pilots.

Such advances "allow aircraft to be more densely packed into the optimum flight routes, creating fuel savings and man-hour savings for the airlines," said Rich Heinrich, manager of advanced system engineering for Arinc.

The satellite system also can transmit data from the aircraft that lets mechanics know what repairs the plane may need after it lands, enabling airlines to avoid maintenance delays.

And with most new commercial aircraft being built with only two-person cockpits, the automation should help replace flight engineers.

While Arinc may find its new technology in demand, reaping big profits from it doesn't appear to be a goal. The airlines who hold its stock formed the company, originally known as Aeronautical Radio Inc., as a joint venture to improve communications technology. Officials say it aims only to recover its expenses, not make a profit.

Although the profit incentive may be lacking at Arinc, its officials feel strongly about their latest product.

"It gives the advantage of economy to the airlines, flight safety and passenger convenience all in one package," said service director David Taylor.

Don Trombely of the Air Transport Association, a trade group, offered a long-term view.

"Everybody's looking forward to getting into the satellite environment," he said. "Eventually, 90 percent of the industry throughout the world will be using it.

"But right now I think they're still at the Orville and Wilbur stage."