NASA Helps Clearing The Fog

By Roland Piquepaille

NASA's Aviation Safety and Security Program wants to cut fatal accident rates by 80 percent over the next ten years. To reach this goal, NASA researchers used "tunnel-in-the-sky" synthetic vision systems (SVS) in recent flights on a Gulfstream V over Reno, Nevada. A guest pilot for Aviation Week & Space Technology (AWST) went onboard and writes that "NASA Team Brings Synthetic Vision to Maturity." He was able to see that SVS concepts, such as voice-controlled synthetic vision displays, a runway incursion protection system, database integrity monitoring technology, and enhanced vision sensors meshed with SVS images, were really effective in eliminating low-visibility-induced accidents. However, NASA doesn't say anything about the availability of SVS for commercial airlines.

Here are selected excerpts of the AWST article about the key concepts behind Synthetic Vision Systems, one of the Aviation Safety Program at NASA.

Researchers aimed to "make every flight the equivalent of clear-day operations -- what we call 'virtual VMC' [visual meteorological conditions]," said Daniel G. Baize, NASA-Langley's SVS project manager. "SVS is another layer of protection on top of enhanced ground proximity [warning systems] -- a great tool in itself -- but synthetic vision will give a more intuitive and more advanced warning of a potential terrain [encounter]."

Although definitions vary, NASA's team decided "enhanced vision" refers to sensor-based means of giving pilots information about terrain and man-made features when visibility is obscured. "Synthetic vision" is an artificial, computer-generated view based on a detailed terrain database. Combining the two can either be done via "fusion" -- creating one image by melding sensor and database elements -- or "integration," which overlays sensor and terrain data.

The latter "provides the flight crew with a synthetic view of the environment, regardless of the weather or time of day," Baize says. "We always start with the database, which includes terrain [and] obstacles. Then we position you within that database to the highest degree of accuracy possible... using a differential GPS system [at Reno]. We then confirm your position in the database with a variety of sensors."

Baize wrote a long presentation about the Gulfstream-V SVS Integrated Technology Evaluation (GVSITE) (PDF format, 48 pages, 6.47 MB). Below are two slides illustrating some key points of the program.

	Here is the definition of a Synthetic Vision System: "a database derived system utilizing precise GPS navigation & integrity-monitoring sensors (as required) to provide a unrestricted synthetic view of the aircraft's current external environment, regardless of weather or time of day." (Credit: Slide 5 of presentation mentioned above)
	And this slide shows the physical components of the vision system under evaluation. (Credit: Slide 10 of presentation mentioned above)

And here is the conclusion of  the other evaluation pilots.

Roy Martin, a Northrop Grumman test pilot, said: "Overall, wow! This is a big, big advancement -- especially for an old round-dial guy. [SVS] is really going to ease pilot workload."

Now, let's hope this technology can be deployed as soon as possible on commercial flights.

Sources: William B. Scott, Aviation Week & Space Technology, August 8, 2004; NASA