BALTIMORE -- Airline pilots flying over the ocean will soon be able to get constant information about their location while passengers could use an in-flight telephone service, predicts an Annapolis company interested in operating the global communications system.

Aviation Satellite Corp., which is one of the two largest private employers in Anne Arundel County, is working on this safer and more convenient type of flying.

When an airliner heads west over the Pacific Ocean from Los Angeles, it now disappears from radar screens and may not show up again until it nears Honolulu, and then again until it nears Japan.

But by late 1989, AvSat hopes to have a global communications system in place that could track the plane from Los Angeles all the way across the ocean, as well as other planes on other routes.

If an airliner strays off course, as a Korean Air Lines 747 did before being shot down over Soviet air space, the system would detect it and the pilot could be notified.

The system, consisting of a satellite and a series of satellite receiver dishes around the globe, could also handle telephone calls from airline passengers. The telephones would be placed in the back of each seat.

"You'll see fewer telephones in airport corridors, too," says Avsat engineer Angus McEachen III. "Instead of people getting off a plane and looking for a pay phone, they will have called their home or office during the flight."

AvSat officials say 14 air carriers from 10 countries have already signed up as "founding" airlines in the venture, said AvSat chairman and chief executive, George F. Mansur.

The capital investment for the project is expected to be about $1 billion over the next 10 years, he said.

Four earth stations will help the new equipment work. One will be at the company's headquarters in Annapolis and the others will be in Honolulu, Western Europe and Asia.

The company expects that the revenue that airlines get from in-air telephone calls will cover the carriers' cost of installing the new avionics equipment, which will cost between $75,000 to $150,000 per plane.

The cost per call would be $2.20 per minute, which the airlines would collect with a credit card entry, plus the telephone company's long distance charges from whichever earth station is used.