System Puts Planes Right on Course : Aviation: The 24-satellite navigation system promises more precise landings. It is expected to replace costlier radar setup.


The corporate jet flew a curved, swooping approach route and settled down comfortably a few feet above Ontario International Airport’s Runway 8 Left.

“Nothing to it,” the pilot, Dave Maahs, said with a satisfied chuckle.

It looked as though Maahs had just made a complex, well-executed landing approach--ending up no more than three feet to the right of the runway center line--at one of Southern California’s major commercial airports.

But Maahs, whose hands had remained in his lap the whole time, actually had very little to do with it.


The twin-engine Gulfstream IV jet had been guided by four satellites 11,000 miles out in space.

It was a demonstration of what FAA Administrator David R. Hinson calls “the biggest single event in the history of navigation.”

That may be stretching things a bit, considering such occasions as the invention of the magnetic compass in the 12th Century and the general recognition, about 300 years later, that the world is spherical.

But there is little doubt that the recent development of the Global Positioning System is a very big deal.


The 24-satellite system is capable of fixing the position of a plane--or a boat, or a car, or a person with a small and affordable hand-held transmitter/receiver--anywhere on Earth. It is far cheaper, far simpler and more precise than the Federal Aviation Administration’s complex air navigation system of radar units and electronic beacons that it is expected to replace within a few years.

Already in use for naval navigation and worldwide mapping, the Global Positioning System is so accurate that it probably will allow planes to take off and land in zero visibility within a few years, the FAA says.

The satellite system was conceived, built and launched by the Defense Department as a method of tracking the movement of troops, tanks and other military paraphernalia in the field.

But when Soviet pilots shot down Korean Air Lines Flight 007 after the Boeing 747 jumbo jet strayed into hostile airspace on September 1, 1983, then-President Ronald Reagan--determined to prevent a recurrence of the tragedy that had claimed 269 lives--ordered that the satellite system be made available for use by everyone.

Joe Dorfler, who had spent 21 years in the Air Force, helping to develop the system, was hired by the FAA to head the adaptation for civilian navigation.

“It’s a classic example of technology transfer from one government agency to others,” Hinson said.

The orbits of the 24 satellites have been synchronized so that at least four are within line of sight of any place on Earth at any time, Dorfler said.

Navigators equipped with Global Positioning System receivers use these satellites as precise reference points to triangulate their position. By measuring the travel time from each satellite, a navigator’s computerized receiver determines the precise latitude, longitude and altitude.


Using one of the hand-held receivers--available these days at a price of less than $1,000--is amazingly simple.

During the FAA demonstration, a pilot was asked to select a hypothetical destination. The pilot picked Los Angeles International Airport, and was told to punch in the airport’s familiar designation--LAX.

An instant later, the display screen on the receiver printed out a series of numbers--the direction to LAX, displayed as a numerical compass heading; the distance to the airport, in nautical miles, and the pilot’s current altitude above sea level, listed in feet.

Although the system does not handle the final touchdown, that, too, will come with time, the FAA says.

Hinson said the system will permit better tracking and coordination of flights by the FAA’s air traffic control system. Radar “blind spots” caused by mountains and buildings will no longer be problems, he said, and the areas of the ocean not now covered by radar will be watched by the satellites.