Synthetic Vision Systems Will Improve Aircraft Safety

Accurate three-dimensional representation is derived from a terrain database of Earth and onboard satellite-based GPS.

by / October 10, 2006
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Hackberry trees and saguaro cactuses fade into the darkness on the valley floor as the sun drops behind the McDowell Mountains, whose faint outline will be invisible in a few more minutes.

The Cessna Citation V jet is flying low -- dangerously low over such terrain at night were it not for a color screen on the pilot console that displays the mountains, an even closer jumble of brown hills and a blue stream of running water as if it were high noon.

It is not a photograph on the screen that Honeywell Aerospace pilot Sandy Wyatt is monitoring, along with traditional needles and gauges, to make sure he is navigating safely.

The image, which is constantly updated during the flight from takeoff to landing, is artificially produced to mimic the view a pilot would see outside the cockpit windscreen on a perfect blue-sky day.

Yet the simulation is an accurate three-dimensional representation of the world outside, derived from a terrain database of Earth and onboard equipment that use the satellite-based global positioning system (GPS) to track the plane's path on the topographical map.

This may sound like science fiction, but synthetic vision is on aviation's horizon.

Proponents -- including the FAA, NASA and some airplane manufacturers -- say combining synthetic vision with technologies that improve real vision will help pilots envision and instantaneously understand what they otherwise couldn't see in bad weather, at night or in challenging flying environments that are filled with natural and manmade obstacles.

"There is a lot of progress being made," said John McGraw, manager of the Federal Aviation Administration's flight technologies and procedures division. "We feel you will end up getting the best of both worlds by fusing synthetic vision with enhanced vision technologies that use external sensors on the aircraft to present the most accurate and reliable image of the real world outside."

Today, pilots must study their instruments and conjure up a mental picture of where they are and what the aircraft is doing based on the aeronautical map in the pilot's lap and cockpit gauges showing airspeed, altitude, course heading and aircraft pitch and roll in relation to the horizon. Those mental calculations take time and talent, adding significantly to pilot workload.

Many accidents occur because the pilot, who should always be thinking about what's coming next -- it's called "flying ahead of the plane" -- fails to keep up with current demands.

With synthetic vision and enhanced vision, which uses infrared or millimeter wave technologies to improve low-vision situations, boosting pilots' awareness of their surroundings is expected to help reduce the two leading causes of fatal aviation accidents -- flying into terrain and loss of control during flight.

More than 3,600 people have been killed over the last 20 years worldwide in accidents in those two categories, according to the Commercial Aviation Safety Team, a joint government-industry group working to reduce the fatal accident rate.

One of the more notable loss-of-control accidents was the 1999 crash of John F. Kennedy Jr.'s Piper Saratoga in the Atlantic. An accident involving a plane flying into terrain happened in 1995 when an American Airlines Boeing 757 crashed into mountains near Cali, Colombia, killing 160 people.

Besides improving safety, the advances in synthetic and enhanced vision research also hold the eventual promise of expanding air travel to hundreds of small and medium U.S. airports that lack the landing-guidance equipment necessary in severe weather.

Over the Arizona desert, the Citation V executive business jet is flying level at 3,500 feet -- too low to clear the more than 6,000-foot mountaintops of the McDowells straight ahead, bathed in darkness.

"Right here it is telling me that I don't want to stay on this tack very long," said Wyatt, development pilot of flight operations for Honeywell, which is one of several companies working on the computer-generated synthetic vision technology.

Distance-range rings incorporated onto the synthetic vision display show the plane's proximity in miles to the exposed bedrock, which changes color on the screen to red, marking the first of several escalating alerts to the pilot.

The most extreme caution is an aural command -- "Terrain! Terrain! Pull up! Pull up!" -- that goes off beginning 60 seconds before a potential collision. But the alert won't be necessary here because the synthetic vision display has given Wyatt plenty of advanced warning.

"It says I am less than 10 miles away so I'd better do something," Wyatt said. He throttles up the jet's twin turbines and dials a new altitude setting of 7,500 feet.

"I am going to miss it," Wyatt assures his passenger on the flight deck.

A pitch reference indicator on the screen confirms the plane is traveling fast and high enough to safely vault over the peaks.

The FAA has approved two versions of synthetic vision for use in general aviation aircraft. The products are made by Chelton Flight Systems and Universal Avionics Systems Corp.

Gulfstream Aerospace Corp., which manufactures business jets, plans to offer the Honeywell version of synthetic vision on its 2007 models, said Gulfstream spokesman Robert Baugniet. He said Gulfstream, which provides enhanced vision on some of its aircraft, expects the FAA to approve the Honeywell system soon.

"Making the Gulfstream planes a tool for the business executive is the ability to go into any airport," said Tom Horne, a Gulfstream senior experimental test pilot on synthetic vision. "Synthetic and enhanced vision gives pilots a much higher comfort level and an immediate awareness if things aren't going the way they should."

No companies have yet sought FAA certification for a synthetic vision system geared to use in the airline industry.

There are several reasons, including the still-emerging nature of the technology. The FAA wants further assurances that the terrain database is without faults. Any potential inaccuracies in the global database that is used to form the synthetic vision presentation of the terrain ahead could lead to pilots receiving inaccurate displays.

The FAA also is concerned that pilots might tend to rely too much on the synthetic vision tool, using it for more than the intended functions and procedures, said the FAA's McGraw.

In addition, the financially struggling airlines are trying to cut costs, not add to their expenses. Several major airlines have gone to synthetic vision vendors seeking demonstrations, industry sources said.

Future safety developments may dictate how fast the technologies find their way into airliner cockpits. The FAA mandated collision-avoidance systems on commercial airplanes after midair collisions between aircraft in the late 1970s, and the agency required ground-proximity terrain warning systems after the 1995 Cali crash.

"The airlines and the FAA are the toughest customers," said Sergio Cecutta, who markets the synthetic vision system at Honeywell.


(c) 2006, Chicago Tribune. Distributed by McClatchy-Tribune Information Services via Newscom. Image courtesy of Honeywell.