As the sun disappeared behind the mountains surrounding Chambery Airport in Savoie, France, we continued the ILS approach to Runway 18 in a Dassault Falcon 8X equipped with the FalconEye head-up display (HUD). Although most of the clouds were high enough at 3,500 feet agl to make it easy to spot the airport next to Le Bourget Lake, visibility was low and it was impossible to see with natural vision the mountains in the deepening darkness. Scattered to broken clouds occasionally obscured the ground, and lights from the town below us peeked through, blinked out, then reappeared.
But thanks to the FalconEye HUD, from the left seat I could easily see the mountains, the lake, the town, and, most important, the runway awaiting our landing.
Dassault engineers have been working on FalconEye since 2011, and it was certified in 2016 in the Falcon 2000 and 900 then in the 8X in early 2017. By year-end, Dassault expects to receive certification for “EFVS to 100 feet” operations in the 8X, then in the 2000/LXS and 900LX in the first half of 2019.
Enhanced flight vision system (EFVS) to 100 feet is the capability under current regulations allowing pilots to fly HUD-equipped airplanes to 100 feet before switching to natural vision to complete the landing. Eventually, Dassault plans to certify FalconEye-equipped jets for “EFVS to land” operations, which means pilots could fly an approach and land without using natural vision to see the runway, although there will be minimum visibility requirements.
Essentially, Dassault is aiming to create a new HUD-enabled capability, which it calls “equivalent visual operation,” or EVO, allowing pilots to land safely at all types of airports in all kinds of weather and without the need for expensive added equipment, time-consuming training, and operational limitations that come with Cat II and III approaches.
Although FalconEye is an option on new Falcons, most buyers, especially those opting for the 8X, are choosing the new HUD. On the new 6X, FalconEye will be standard equipment. Dual HUD installations will also be available for the 8X and 6X.
The benefits of FalconEye aren’t just in facilitating IFR approaches, but more importantly in improving pilots’ situational awareness. For the first time, it combines live enhanced vision system (EVS) imagery with database-driven synthetic vision system imagery on a HUD. FalconEye is the first combined vision system (CVS) to achieve EASA and FAA certification.
Dassault’s work on CVS isn’t the only such effort. Honeywell has successfully demonstrated CVS on a head-down display (primary flight display), with the EVS and SVS imagery combined together—overlaid conformally—a tremendously difficult challenge. Pilots who have flown the Honeywell CVS were able to land well within the tight parameters of a specific box near the runway touchdown zone almost every time, with excellent repeatability.
The Rockwell Collins HUD on the Bombardier Global 6000 and its HGS 3500 compact HUD on the Embraer Legacy 450 and 500 can display both EVS and SVS imagery, but not at the same time. The CVS on the new Global 5500 and 6500 is fully conformal.
In designing FalconEye Dassault engineers had to decide whether to try to combine EVS and SVS by overlaying the imagery conformally or to devise a better solution. Overlaying the imagery is hard because SVS is derived from a terrain database, and the data need be off only slightly for the SVS image not to be conformal—not matching exactly the real-time EVS image, which comes from onboard sensors and cameras.
The FalconEye solution was to give the pilot leeway in how to display EVS and SVS imagery on the HUD and to allow both to be displayed at the same time, but not overlaid. As a result, FalconEye allows the pilot to adjust a horizontal split line between EVS and SVS, moving the line up or down the HUD combiner depending on the particular outside environment. For example, during the approaches that I flew at Chambery, I could set the split line on the horizon so I could see the visually obscured mountains depicted clearly on the SVS, and below the split line I could see the EVS imagery of the town, lake, roads, and airport.
But what about seeing terrain surrounding the immediate airport environment on SVS? Dassault engineers cleverly figured out how to include the benefits of EVS even when SVS is the predominant image displayed on the HUD. What they did was carve out a conformal runway clear zone around the airport, so even if the airport is within the SVS depiction, the selected destination runway is clearly visible via EVS inside the clear zone.
The FalconEye system consists of an Elbit HUD with a large field of view of 40 degrees horizontal and 30 degrees vertical and 1,280 pixel horizontal and 1,024 pixels vertical resolution. Maximum brightness is 3,000 foot-lamberts, which ensures that HUD symbology is bright enough even during the daytime. FalconEye, in fact, can be used as a primary flight reference during all flight phases and all allowable types of operations.
The EVS side of FalconEye consists of an Elbit multi-sensor camera mounted on top of the airplane’s nose. The camera is fitted with four day sensors and one night sensor, and these are for detecting lights during the day or night. A thermal sensor is for terrain imaging.
Combined, these six sensors capture details in the visible wavelength and near- and long-wave infrared wavelengths. The output from the sensors is mixed and matched to provide two functional modes selectable by the pilot: high mode for high-visibility conditions and low mode for low-visibility.
During the flight around Chambery, with Dassault test pilot Philippe Rebourg flying right seat, I flew four approaches, including ILSs to minimums on Runway 18, circling approaches to Runway 36 and missed approaches. I tried many variations of adjusting the split between EVS and SVS during the approaches and observed the benefit of the airport clear zone with EVS while SVS showed the nearby mountainous terrain.
With the five visible-light sensors and the infrared sensor, the EVS mode depicted clouds below us in different colors, some gray and dark and others white and green, depending on which sensor was providing the information to the HUD.
In the clear zone, I could easily see the runway boundaries and edges, approach light bar symbols—which matched the location of the approach lights so the pilot knows where to look—and runway lights. When flying toward the airport, the runway is easily visible, at first identified by a 1,000-meter-high pole topped by the runway’s magnetic orientation number (QFU) to help the pilots find the end of the runway, then as we flew closer to the airport, by the clearly marked borders of the runway.
While flying the final circling approach, I turned a bit late to the downwind leg, and I could see a hill in front of but still below us in the SVS. We would have cleared it, which I could clearly see by looking at the flight path vector pointing above the terrain depicted on the SVS imagery, but for maximum safety, I turned back toward the airport and away from the terrain.
After flying with FalconEye for more than two hours in the 8X, I came to appreciate the massive improvement in situational awareness, as well as how it helps pilots fly smoother and with greater safety during low-visibility operations, especially when high terrain is involved.