It’s easy to confuse the Max-Viz enhanced vision system (EVS)with popular synthetic vision systems (SVS). These include Garmin’s proprietary SVT and Aspen’s ESV synthetic vision software. While synthetic vision is just that—a GPS-based synthetic depiction of terrain, obstacle and landscape features—the Max-Viz product from Oregon-based Astronics is a live moving image of the outside environment.
288
Max-Viz isn’t a new product. It’s been in use in a variety of military and tactical applications, plus select general aviation applications. But a growing list of STC and TC approvals is giving the product legs for more retrofit and OEM installations.
Uncooled infrared
The Astronics Max-Viz is an electro-optical system that uses a long-wave infrared sensor and a visible light camera that’s usually mounted on the underside of the wing. The model EVS600 relies on the infrared sensor to produce an image of heat signatures on the earth, while the low-light CMOS camera enhances it. Software processing then fuses the two images into one before it’s transmitted to the cockpit display.
Unlike a video camera, the Max-Viz thermal imaging detects differences in heat, rather than differences in light. Moreover, some complex infrared systems, known as photon-sensors, require refrigeration units to cool the sensor to subzero temperatures so it can detect heat sources. Given the size and the expense of the equipment, these older cryogeneric sensors just aren’t practical for small aircraft.
The uncooled, heat-detecting sensor array in the Max-Viz EVS is microbolometer-based. This technology has been around since the 1970s, but was classified until the early 1990s because of its use in military night-vision systems.
Night to day
We flew with the EVS600 in a Garmin G1000 Perspective-equipped Cirrus SR22, one application where Max-Vis is available as a factory-installed option or for retrofit. The system is also an option on new Cessna 172, 182 and 206 models. In the aftermarket, there are over 200 type-approvals in place, including an AML-STC for all existing single-engine Cessna models, except the P210. Max-Viz is also approved for the Robinson R44 helicopter.
375
While the system can see through haze, smog, smoke and some precipitation, it won’t see through clouds. We found the system particularly useful in darkness, especially while maneuvering around the airport environment (and during taxi).
Astronic’s Lou Churchville told us that fusing the visible-light camera with the infrared sensor was intended to give pilots the most unambiguous, at-a-glance situational awareness during night operations, especially when approaching a dark runway environment—a claim we agree with, based on our flights.
To appreciate the effectiveness of the light-seeing camera, you need to understand the limitation of infrared technology. Unlike the human eye, a long-wave infrared sensor won’t see visible light, which means important airport-identifying features like runway and taxiway lights would be missing from the EVS image. Conversely, the EVS infrared sensor is effective in low visibility because the thermal energy from the ground is able to penetrate visibility-limiting atmospheric particles (usually smaller than 12 microns). But temperature-based imaging has limitations, especially in heavier precipitation and thick fog. Depending on the location of the sensor, performance could be degraded by heavy rain, especially in certain airflow conditions. The fixed field of view is 40 degrees wide and 30 degrees vertical. The sensor housing, which weighs 1.2 pounds, has integral window heaters for operation in icing
The displayed monochrome resolution of the EVS image is 320×240 pixels, which isn’t great compared to what you might be accustomed to with most modern cockpit displays and televisions. It will likely look worse on smaller displays.
Strategic use
While we went flying on a relatively clear night, we ventured over the mountainous terrain in the Berkshires of western Massachusetts. On the dark, icy taxiway at Pittsfield Airport, the combined image made taxiing a no-brainer. The EVS infrared sensor picked up the heat of the pavement, painted centerlines and surrounding trees, while the visible light camera saw the taxiway lighting.
With mountains on both sides of the departure end of the runway, the EVS was useful during the dark climbout, displaying the surrounding terrain and clouds as if it were daylight. But the real advantage, in our view, is during approaches in low visibility and clouds.
On the G1000, one strategy is to transition from the moving map to the EVS once the aircraft is inside the final approach fix. Using the EVS camera, you’re looking for the runway lead-in lights and the features of the surrounding runway environment. If the EVS doesn’t pick up ground signatures as you get closer to minimums on the approach, it’s a pretty good bet that you’ll be making a missed approach.
Enroute, EVS can be helpful for surveying cloud layers and terrain. On the runway, it can identify wildlife and other aircraft.
Not a cheap buy-in
The list price of the EVS600 system is just shy of $18,000 and doesn’t include a display. The EVS600 is targeted at aircraft with speeds below 250 knots. The EVS1500 is for turbine applications, has dual pilot-selectable field of view and a zoom feature.
You don’t need a G1000 display for displaying the EVS image. Any MFD that accepts a RS170 coaxial auxiliary video input (including the Garmin G500/600) will work. There’s a variety of aftermarket portable monitors, plus the system is known to work with the new AVMAP EKP portable GPS and a variety of EFBs. Visit www.max-vis.com, 888-629-7888.
