NASA partners show EVS, SVS concepts

 - October 18, 2006, 10:02 AM

Throw BAE Systems and Nav3D into the mix of companies indicating strong interest in sensor and software technology for emerging cockpit advanced-vision systems.

Combining forward-looking sensors with detailed terrain and airport databases, BAE Systems has enhanced- vision concepts under development that are similar to technologies other firms have demonstrated, but with a notable exception. Rather than relying solely on infrared (IR) cameras for views ahead of the aircraft, BAE Systems has in mind a combination of short- and long-wave IR sensors and a view from a millimeter-wave radar, using a process that fuses the three images into one coherent picture displayed on a HUD.

More than a dozen pilots have been evaluating the enhanced- and synthetic-flight-vision display systems aboard a NASA Boeing 757 based at the Langley Research Center in Hampton, Va. The synthetic-vision display system is the brainchild of engineers at Nav3D, a small software company based in San Carlos, Calif. More than 100 people–both from NASA and private industry–have been involved in the project, which was born out of a mandate handed down by a 1997 Presidential Commission aimed at reducing fatal accidents.

NASA researchers have embraced advanced-vision technology as a way of dramatically reducing accidents among airline and general aviation operators, saying the technology currently under development holds the potential to “virtually eliminate” air disasters caused by controlled flight into terrain (CFIT). NASA’s goal is not centered on entering the commercial arena to produce advanced-vision systems but rather on preparing industry to take the concept much further, according to project insiders.

During a demonstration of the technology last month in NASA’s 757, it was clear that this program parallels similar advanced-vision work done by other NASA industry partners, namely Boeing, Gulfstream, Rockwell Collins and enhanced-vision system (EVS) maker Max-Viz–although there were a number of differences among the various iterations of the technology the companies have shown the aviation trade press in the past and what NASA demonstrated last month.

In the nose of the 757, BAE Systems has installed a trio of sensors. The infrared cameras included a short-wave IR sensor tuned to the 0.9- to 1.5-micron level, which is used for detecting high-intensity runway lighting, and a long-wave sensor, more suited to picking out terrain and obstacles. Because IR cameras do not do a good job seeing through clouds and heavy fog, BAE Systems has modified a Collins WX-2100 weather radar with a 94-GHz millimeter-wave imaging sensor, which casts an image on the HUD by transmitting a radar pulse reflected off surfaces in the distance, without interference from most types of moisture.

BAE Systems has been demonstrating the technology for more than a year, mainly to military audiences. The NASA trials bring the concept to pilots from other segments of aviation, including the airlines, where the potential for improvements in operating efficiency could help make the business case for EVS and synthetic-vision systems (SVS).

Using an SVS display system with highway-in-the-sky (HITS) guidance, pilots can fly complex curved approaches that are more complicated than anything found in a Jeppesen approach chart book, said Andrew Barrows, CEO of Nav3D, which wrote the software code the system uses.

“The synthetic-vision display is used on approach, and then the pilot transitions to the head-up display and the EVS image,” Barrows explained. “The combination of these technologies reduces pilot workload and provides unmatched hand-flown precision.”

The terrain database used for this demo exercise–a morning flight from Langley Air Force Base to the nearby Wallops Flight Facility to shoot SVS approaches–included photo-realistic views of the ground, water and airport on large glass flight displays in the cockpit. Observers stationed in the back of the airplane could watch any one of several monitors carrying flight display and HUD views to see how the pilots up front were doing.

First-time UsersFly the System with Ease

In the case of this flight, the pilots were a couple of Air Force pilots, Maj. Aaron Reed, a C-5 pilot with the Air Mobility Command, and Maj. Dave Sprague, a long-time C-21 and tanker pilot. Reed and Sprague were not part of the formal evaluation group that has been testing the various systems and, in fact, had received no formal training whatsoever in flying with EVS or SVS.

The reasoning behind letting the newcomers fly the system was twofold. First, the Air Force was interested in hearing the pilots’ reaction to the technology and, second, NASA was interested in gathering anecdotal input from pilots who had never flown with this type of technology.

To say the Air Force majors flew well is an understatement. The SVS approach to Wallops was a tightly curved descending path to the runway with tunnel boundaries of 500 feet wide and 300 feet high. Instead of square or rectangular tunnel boxes, this SVS display used rectangles with angled “roofs,” reminiscent of a child’s drawing of a house. (NASA said human-factors research demonstrated pilots preferred this shape and learned to fly more precise approaches with it.)

A flight-path-vector marker was used to predict where the airplane would be in five seconds. As long as the pilots kept the flight-path marker inside the boxes, they could be assured they were within the parameters of the approach. There was another, much smaller rectangle inside the tunnel, and if the pilots kept the flight path marker within that box it meant they were flying to better than Category III tolerances.

On each of his approaches, Maj. Reed never strayed from the inner box, and on the six approaches he flew, Maj. Sprague spent a total of 15 or so seconds outside the inner box. Neither pilot flew outside the outer box, which was all that was required.

During on-the-fly evaluation sessions, where each pilot answered a series of questions about his experience while setting up for the next approach, both said the HITS tunnels were “extremely easy and intuitive” to hand-fly and stated that situational awareness was “exceptional.” Where the pilots had complaints was during the initial transition from flying outside the boxes to inside the course. This transition was somewhat confusing, both agreed.

Likewise, the Air Force pilots were less enamored of the EVS view through the HUD (they flew the approaches with a screen intentionally blocking their forward view), which they described as being similar to a night landing.

One pitfall of HITS that NASA has discovered during simulator sessions is a near complete loss of instrument scan by the pilot. The problem has to do with the fact that the pilot is concentrating so intently on flying through the HITS tunnel that he actually loses situational awareness. Instructors have stopped the simulator midway through the approach and asked pilots to tell them what their altitude and airspeed were just before the sim was paused. Far more often than not, the test subject did not know the answers. Training is the key to remedying this shortcoming of the technology.