A persistent problem for U.S. helicopters in Afghanistan has been landing amid brownout conditions. Light reflecting from the fine particles of dust kicked up by sandstorms or a helicopter's own rotor blades often leave pilots flying blind and unable to see poles, trenches and other hazards.
Several industry firms and groups are working to reduce those dangers, including BAE Systems and a CAE-Neptec team.
Called synthetic Augmented Visionics System (AVS), the latter combines data from Ottawa-based Neptec's Obscurant Penetrating Autosynchronous Lidar (OPAL) system and forward-looking infrared (FLIR) sensors, then adds the sensor data to the CAE-developed Common Database (CDB) of ground features. Any differences - for example, a new communications antenna - are instantly rendered in 3-D form on the pilot's head-down or head-mounted displays.
"The lidar allows us to penetrate the brownout and give us a reference to the ground and obstacle detection, even while the helicopter has created a whole dust cloud," said Louis Dontigny, CAE's chief engineer for the AVS. "We're not just talking about instrumenting an aircraft with needles and a few things to just try to give him information for the pilot to fly, but really to give him a perception of what's around him."
The CDB allows constant input into the changes imposed by the conditions, and pilots don't have to rely on visual cues.
"And you keep updating that as you fly into brownouts because if something comes in, like a Jeep or Humvee or something else, you still detect that," Dontigny said. "It's a concept that you don't have to detect and classify everything all the time. Once you detect it, you know what it is. So you refine your database; you're not regenerating the whole database all the time."
Dontigny said the AVS, which remains more a technology than a finished product, will work best on large helicopters such as the CH-47 Chinook or tilt-rotors such as the V-22 Osprey, which cannot make evasive maneuvers as easily in brownouts as smaller helicopters.
"Everybody I hear who has been to Afghanistan is worried that we're going to crash a Chinook," he said of the heavy-lift aircraft.
The U.S. Army reported more than 50 brownout incidents with damage in 2001-07, 80 percent of which occurred during landings. The service blames brownouts for three of every four helicopter accidents in Afghanistan and Iraq.
Lidar sensors work more effectively in brownouts than FLIR because the temperature of the dust particles on the ground is essentially the same as those in the cloud. FLIR uses thermal energy to detect warm objects against colder backgrounds.
But even lidar sensors have limitations in thick dust clouds, said Neptec President Iain Christie, who likened it to turning on a "headlight in a fog" while driving a car. "You don't really see anything except a bright glow in front of you," he said. "Well, lidar trying to see through dust is the same thing. The light gets scattered and reflected off the dust particles and it swamps the detector, so that the detector can't actually see anything except for the bright glow off the dust that's coming from everywhere."
Christie said he couldn't divulge all details of the product, but said OPAL gets around that "bright glow" effect because it's designed to look only in the direction "where you want to see stuff."
Detection can include objects down to a half-inch in size as well as 4-inch trenches in the ground, Christie said.
"We're working in cycles of about six seconds for updates, which is the real-time database type of update," Dontigny said.
CAE is demonstrating the AVS using head-down displays.
"We're looking at using ruggedized flyback - a ruggedized laptop built for use in aircraft - for the first version," he said. "Right after, it's going to go to a helmet-mounted version."
For CAE, pilots who rely on synthetic systems such as the Advanced Visionics System to land helicopters in brownouts need to alter their mind-set that places trust on visual cues. Dontigny agreed that for now, pilots "will still prefer to use visual cues simply because they now have them."
But discussions with dozens of helo pilots on using the AVS have brought positive feedback "because it gives them, for a minimum of training, the maximum information they need in landing the aircraft," he added.
AVS isn't ready for installation on field helicopters, but CAE officials consider it feasible within two years. The company wouldn't provide details on possible customers and said most research to date has been funded internally. But the U.K. Ministry of Defence is interested, they said.
The long term brings possibilities for use by the commercial market too, Dontigny said.
For now, CAE is hoping that AVS will take off with military clients. Neptec's Christie said the elements are in place because the capabilities offered by OPAL and CAE's overall expertise in visuals combined with the availability of the CDB provide the best solution.
OPAL can see things not only down to a fraction of an inch but also through dust. "There are lots of systems that can do one or the other, but there aren't any that can do both at the same time," he said.
"The technology is ready to go; there are still questions about how to make it work for a pilot because you need to have a pilot and an airplane to answer those kinds of questions," Christie said. "But there's no question in our minds that all the capabilities are there."
Many companies are claiming some kind of capability to solve the brownout problem, Dontigny said.
"And I think there is something reasonable for the very small helicopters. But the Little Bird [light assault helicopter used by U.S. Army Special Forces] and the Chinook are not the same problem as far as brownouts."
AVS presents a solution not available elsewhere for large rotary aircraft, he said.
BAE Systems also is researching a program designed to use visual situational awareness technology to overcome brownouts.
"We are trying to tie together a reference architecture of active and passive sensors and man-machine interface to solve not only brownouts - honestly, we are also looking at cable and hazard avoidance - and that's all on a high level," said John Nix, BAE's vice president of business development for defense avionics.
The company uses a 94-gigahertz sensor "that allows us to see through dust," combined with laser detection and ranging sensors, Nix said.
"That's going to give them kind of a fused artificial image of the objective area and allow them to see any obstacles," Nix said. "We're trying to let the aviator operate day/night all-weather and not be constrained by the environmental conditions, i.e., either fog or dust or snow, any of those kinds of things."
BAE spent two weeks at Yuma Proving Ground in Arizona in late summer testing the technology - "shooting energy into a dusty environment" to locate hazards is how Nix described it.
Tests have demonstrated that the technology can locate objects such as a wire in a dust cloud, Nix said.
"We're now pulling to an end-to-end flight demonstration where we take the passive system with the [low-vision landing] symbology and the [head-mounted display] and add the active sensor - 94-gigahertz sensor - and fly that in the real world."
Video 
Help
