Enhanced Vision System - Curt Lewis

Combined Vision For Airliners

Avionics providers are targeting the air transport market as ideal for combined vision systems (CVS), cockpit avionics that fuse synthetic vision with forward-looking infrared (IR) sensors and other real-time detection systems to boost situational awareness for pilots and increase schedule reliability for airlines. 

Two key contenders in the sector are Elbit Systems and Rockwell Collins, both of which are developing end-to-end (sensor-to-display) systems. Key to gaining buy-in from airlines will be new regulations that allow carriers to take advantage of the technologies as well as highly reliable and relatively low-cost product offerings, both of which appear to be coming to fruition. 

While the CVS products remain in the development stage, the two core technologies behind CVS-synthetic vision systems (SVS) and enhanced flight vision systems (EFVS)-are mature and have separately become standard fare in a variety of business aircraft and with at least one large cargo carrier, FedEx. 

SVS, a database-driven 3-D representation of the view through the windscreen complete with specialized symbology, is already commonplace on general aviation and business aviation aircraft, but not yet on airliners. The reason, in part, is because the tool is available as a situational awareness aid only and does not provide any direct economic benefits such as lower landing minimums for instrument approaches. As is often the case, the technology first emerged in the general aviation and business aviation market, where Rockwell Collins's most advanced system features SVS operating on the head-up displays (HUD) on more than 250 Bombardier Global Express aircraft. 

EFVS takes video from a forward-looking IR sensor, which is typically cooled, and displays the scene along with computer-generated symbology on a HUD in the cockpit. With approved equipment and training, operators can use it as a proxy for natural vision to descend 100 ft. below the typical 200-ft. minimum altitude for a Category 1 instrument landing system approach before spotting the runway environment with natural vision. Elbit subsidiary Kollsman Inc. is a leading manufacturer of the cooled IR cameras, which are installed in the nose of a large number of business aircraft and on FedEx's fleet to help avoid low-visibility weather diversions at the large number of international airports with Cat. 1 approaches. 

The extra credit, along with an exemption from the FAA, was a selling point for FedEx to install the equipment, which costs approximately $1 million per aircraft. The exemption gives the carrier relief on an FAA dictate that prevents airliners from departing on a flight or beginning an instrument approach at the destination airport if the visibility and cloud height are forecast to be below minimums for the procedures. 

An update on the FAA's EFVS rules, expected to be issued by year-end, will remove the so-called "approach ban" that led to FedEx's exemption and will allow EFVS to be used in lieu of natural vision down to the runway. The European Aviation Safety Agency (EASA) is also planning to liberalize its vision system rules, creating a new approach category within two years that will in part cater to aircraft equipped with CVS, both with HUD systems or classic head-down displays. 

The holism of combining SVS and EFVS, along with lower-cost IR sensors and a rule change, could tip the cost-benefit scales enough that airlines take an interest in CVS. Each technology has its individual weaknesses-SVS is based on a static snapshot of terrain and obstacles in a database; EFVS is limited by the performance, reliability and cost of its sensor. But the fusion of the two offers the best of both worlds, a constant daytime view of the flight path ahead and intuitive situational awareness cues.

Moreover, both Rockwell Collins and Elbit are using lower-cost and more reliable noncooled EFVS sensors, which the companies say reduce acquisition costs and boost sensor reliability. "All of the EFVS cameras are cooled," says Craig Peterson, senior director of marketing at Rockwell Collins. "That is not the kind of mean-time-between-failure [MTBF] that an airline customer would be looking for." Elbit advertises a 5,000-hr. MTBF for the Kollsman EFVS camera and 9,000 hr. for its four-camera noncooled ClearVision that is part of a CVS project for regional aircraft manufacturer ATR. Critics of the noncooled technology say it cannot perform as well as the cooled sensors in low-visibility conditions. 

ATR is betting that its airline customers will be interested in its noncooled CVS proposition. The airframer is working with Elbit and EASA to certify a CVS for the ATR 42-600 and ATR 72-600 twin turboprop commuter aircraft, a project the companies expect to complete in 2017. The option includes Elbit's four-camera, forward-looking sensor and a head-mounted pilot viewing device (in lieu of a HUD) that is akin to wearing a pair of ski goggles. 

Elbit anticipates gaining approach "credit" from regulators to allow pilots to descend from the normal Cat. 1 instrument approach minimums of 200 ft. above the runway down to 50 ft., with pilots using the CVS in lieu of natural vision. At 50 ft., the crew would have to spot the runway with natural vision to continue with the landing. 

Rockwell Collins does not have an active CVS certification program with an airframer underway, but it is completing an end-to-end EFVS certification program with Embraer for its HGS-3500 compact HUD and EVS-3000 EFVS for the Legacy 450 and Legacy 500 business jets, an approval the avionics-maker says will likely occur in June. The combination is expected to cost about half of what a cooled EFVS sensor and standard HUD would. 

The company demonstrated its CVS prototype to Aviation Week in February on a flight in the company's Challenger 601 avionics testbed from Wichita to the Eagle County Regional Airport in Colorado, a challenging proposition at night in the best of conditions due to the mountainous terrain. The aircraft has a HUD above the co-pilot seat and the EVS-3000 sensor in the nose, with the ability for the test pilot to switch between SVS, EVS and CVS on the HUD. 

Carlo Tiana, an airborne vision systems expert with Rockwell Collins's HGS operation in Portland, Oregon, says the EVS-3000 was designed "from the ground up" to address the shortcomings the engineers found in working with other manufacturers' cooled IR cameras coupled with Rockwell Collins HUDs for EFVS systems. "We had accumulated a big, long wishlist from the technical side that caused us to consider the design of this camera," he says. The result was a camera with three uncooled sensors mounted side by side, covering the visible spectrum (0.4-0.9 microns), short wave IR (1-2.5 microns, the spectrum that picks up incandescent lights, including approach and runway lights) and the long-wave spectrum (8-12 microns), which reveals terrain. The sensor imagery from the three cameras is fused based on an algorithm that selects the best combination for the phase of flight and conditions. 

Arriving into Eagle County on a very dark night in visual conditions, it was readily apparent by cycling through the different options that the combination of SVS and EFVS was far superior than either technology alone. SVS alone is intuitive, particularly with Rockwell Collins's unique features that highlight ridgelines and place a virtual dome over the destination, but it lacks the real-world characteristics you expect to see in populated areas-lights and subtle changes in terrain. EFVS alone leaves much to be desired in terms of its range, situational awareness and symbology. 

While the project remains in the research phase, Tiano says Rockwell Collins is developing a second-generation camera that will technically be similar to the three-channel EVS-3000 but with new packaging and refined aerodynamic shape. "It will probably be for the air transport market," says Peterson. 

"One aspect of the new design is getting the size and the weight and cost down to a price point where it will be accepted in the air transport market, which is far more price-sensitive than your average business jet owner," he says.