ARCHIVED - A Third Eye for Helicopter Pilots
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August 03, 2003— Ottawa, Ontario
Driving a car in the snow or fog is dangerous enough, but imagine flying a helicopter. Wires, trees, and even hills can pose a serious risk to low-flying helicopters, especially when visibility is poor. Since helicopters frequently perform search and rescue missions and emergency evacuations, they often face less than ideal weather conditions.
|In poor visibility, a hovering helicopter could easily drift towards a tree line or other object without the pilot's knowledge|
For the past three years, the NRC Institute for Aerospace Research (NRC-IAR) has been testing a radar system that can see through anything Mother Nature has to offer. OASys, which stands for Obstacle Awareness System, is a millimetre wave radar developed by Amphitech International of Montreal. OASys overcomes some of the limitations of other systems that rely on lasers to spot obstacles. "The problem with lasers is they suffer the same limitations as our eyes," says NRC-IAR Test Pilot Stephan Carignan. "When there is water or clouds or fog, they can't penetrate as well."
Unlike lasers, the OASys radar works in almost any weather. The system sends out a pulse that bounces off obstacles and then returns to the radar, which pinpoints the location of any "hits". OASys detects objects in a range of one to two kilometres. The pilot gets an 8 or 16-second warning, depending on how dangerous or close the obstacle is.
Amphitech developed the OASys technology with financial assistance from the NRC Industrial Research Assistance Program (NRC-IRAP), which also referred the company to NRC-IAR when they were looking for a flight test facility.
In a series of flight tests, NRC-IAR's pilots helped Amphitech to fine-tune the complicated algorithm that determines how the radar detects and responds to obstacles. "At first, we would fly over cities and it would pick up the rooftops as obstacles, because they're nice and flat," says Carignan. "Or during an approach, it would say you're about to hit the ground, but of course I know this because I'm about to land."
With NRC-IAR's input, Amphitech modified the algorithm to smooth out these wrinkles. The system uses the aircraft's speed, flight path, altitude and other indicators to deduce where it's headed, and then scans for any obstacles in that zone. It constantly changes the warning zone depending on the helicopter's motion. "So if the aircraft rolls to the right, the system recomputes the flight vector and the warning zone gets moved to the right," says Carignan.
|OASys installed on NRC-IAR's Bell 412 research helicopter.|
Relaying these warnings to the pilot was a key part of the tests. "Determining whether something is an obstacle is one thing, but it's equally important to display it to the pilot so that he knows where it is," says Carignan. Amphitech hired CMC Technologies to design the visual display. A screen mounted on the helicopter's dashboard lights up a series of indicators to show whether the obstacle is wide (such as a hill), or tall (such as a tower or tree). The pilot also receives an audio warning, which changes and gets louder as the object gets closer.
The biggest market for OASys is emergency medical helicopters, but the radar system also has potential for military use. Not only does it give pilots a third eye, but could also act as the only set of eyes when there is no pilot. Unmanned air vehicles (UAVs) are increasingly being used for dangerous roles in war or for long and tedious jobs, such as satellite planes that fly in low orbit for weeks at a time.
"UAVs are kind of the next generation of aircraft," says Carignan. "Right now, designers are looking at using the millimetre wave radar to act as their eyes."
The system doesn't come cheap; it costs about $100,000 per aircraft. Carignan says this isn't bad, considering the average price of a helicopter ranges from $2 to $6 million. "For most fleets, if it saves one helicopter over ten years, it's paid for itself," he says.
- Aerospace Research at NRC
- NRC Institute for Aerospace Research
- NRC Industrial Research Assistance Program
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