Posted 9 years 239 days ago ago by Admin
White Hot: Adding a Thermal View with EVS
By Rick Adams
I was driving on the turnpike through western Massachusetts a number of years back, enroute to Boston, and the fog was thick. I should have pulled off and waited for better conditions, but I had a hotel reservation for that night and appointments the next morning. So I followed the only visual aids I had – the stripes on the side of the road and the taillights of the car in front of me. If the car ahead had gone off a cliff, well …
Flying a helicopter in a degraded visual environment – clouds, rain, fog, night – can be a lot like that. Except in a rotorcraft, you don’t have the option of pulling over into a rest area for awhile.
When you’re in low-visibility conditions, or find yourself in an inadvertent IMC situation, the stress levels spike, and your mind can struggle to process the information overload.
“Aural cues are one of the first to go under stress,” says Bob Yerex. “You’re very probably not going to even hear the terrain warning system.” Yerex manages rotary wing sales for Astronics’ Max-Viz, headquartered near Buffalo in East Aurora, New York. He’s been a Coast Guard search-and-rescue (SAR) pilot, airline pilot, and single-pilot IFR helicopter operator.
“It’s not an easy transition for the brain” to shift from VFR to IFR, Yerex explains. “It’s more difficult at night when you’re not able to see the clouds at all and have limited lights on the periphery.” Some studies show a mental delay of 3-5 seconds during transition, by which time you’ve flown another 300-500 feet through the soup without knowing what’s in front of you.
One solution that more civil helicopter pilots are adopting is a basic enhanced vision system (EVS). EVS presents a black-gray-white image on a cockpit monitor using infrared or thermal imaging, i.e. its sensors interpret the differences in heat ‘signatures’ of objects in the field of view: buildings, towers, trees, runways, vehicles, aircraft, people, animals, rocks, and so forth.
The imagery presented on the monitor is quite intuitive and simple to interpret (unlike synthetic vision symbology-based systems). With thermal, the more heat an object gives off, the whiter it will appear; thus, the term “white hot.”
EVS thermal imagers are often referred to as cameras, but in fact they are comprised of thousands of tiny ‘microthermometer’ sensors. FLIR Systems, a leading producer of electro-optical systems for a wide range of aviation and other applications, claims “you have a much better chance of seeing something at night with a thermal imager than you do with a visible light camera, even a night vision camera.”
In Thomas Madden’s opinion, “You could turn off all the other instruments in the ship at night and fly from Point A to Point B utilizing just the images on the EVS screen.” Madden is a partner in TrueView EVS, located in Sackets Harbor, New York, which entered the business three years ago.
“EVS makes controlled flight into terrain (CFIT) an impossibility,” Madden claims. “EVS can eliminate nearly all of the hazards associated with night flight, or leaving the base early in the morning when visibility is low.”
It was a February 2000 US Federal Aviation Administration (FAA) joint safety implementation team report which recommended “increased support of programs that will expedite development, certification, and voluntary installation of low-cost safety-enhancing CFIT equipment … [including] look-ahead terrain warning systems available for voluntarily installed, low-speed general aviation aircraft.” Prior to that, thermal-imaging aids had been predominantly the domain of military aircraft.
“Approximately 80% of the hazards related to our flight operations” can be tied to night and inadvertent IMC conditions, notes Kevin W. Nelson, President, Nelson AeroDynamiX, Traverse City, Michigan. A Max-Vis EVS user, Nelson says, “I have found, in a short amount of time, my comfort level in reduced visibility and night flight is much greater. I fly with it all the time and make it part of my scan.”
Max-Viz: Dual FOV
Max-Viz, a small, venture capital-backed engineering business acquired last year by Astronics, introduced their first product for civil helicopters, the EVS1000, the same year as the FAA CFIT report. The current flagship product is the Max-Viz 1500, which features a 320 x 240 pixel resolution, and pilot-selectable dual field of view (53-degrees horizontal by 40 degrees vertical ‘wide angle’ or 30H x 22.5V ‘telephoto’). The unit weighs about five pounds total and mounts to the nose of the aircraft.
Max-Viz 1500 is uncooled, and Yerex says that brings the cost in about 75% lower than for the type of cryogenically cooled systems often mounted on high-end business jets. He notes the simpler design is also more reliable with greater than 12,000 hours mean-time between failures, which is “more than the lifespan of most aircraft.”
Astronics’ EVS is certified on a variety of AgustaWestland, Bell Helicopter Textron, Eurocopter (to be called Airbus Helicopter as of January 1, 2014), and Sikorsky turbine-powered rotorcraft.
The company’s Max-Viz 600, rated for operations below 250 knots and altitude below 25,000 feet, is certified for the Robinson R44. It blends infrared with a visible light sensor for a fused visual display.
“With EVS, pilots are able to see obstructions and therefore avoid obstructions,” Yerex points out. “We recommend crews turn it on when they spool up the aircraft and turn it off when they shut down.”
TrueView: High-Res Tilt
TrueView’s T6-200 EVS features a considerably higher sensor count, 640 x 480 resolution, or more than 300,000 pixels (using FLIR Systems camera cores) for an image which Madden calls “absolutely no contest.” The T6-200 is about the size of a coffee mug, weighs a mere pound, and a retrofit installation can be done in 20-30 man-hours, including a prefabricated wiring harness.
Another TrueView feature is tilt – up to 28 degrees incrementally and designed for single-pilot use. “No one else has it,” according to Madden. “The pilot doesn’t have to use the aircraft as an aiming device.”
Madden says that with non-tilt EVS systems, “the pilot will lose sight of the landing zone at some point during approach” when the nose pitches up. But with TrueView, the pilot can maintain visual contact with the landing zone at all times.
The T6-200 recently received a supplemental type certificate (STC) for the Bell 407 and 407GX aircraft types, including the use on the GX of the Garmin 1000 for the infrared display. TrueView also has STCs in the US and Canada for Bell 206B and 206L series aircraft. Bell’s Aeronautical Accessories is a TrueView EVS distributor worldwide.
A Sikorsky S76 installation is just about complete with two displays, one for the pilot and the other for emergency medical personnel in the cabin.
The cost of installing EVS is generally less than $50,000 USD, which Madden suggests is a “rounding error” compared with overall helicopter operating costs. “But it adds a significant level of protection to every flight.”
Rick Adams has more than 30 years’ experience writing about aviation and safety. He is editor of InterPilot magazine, published by the International Federation of Air Line Pilots’ Associations.