Honeywell is continuing development of cockpit technology that makes pilots’ jobs easier and that will help in that most fundamental of piloting tasks, landing safely in poor weather. What is unique about Honeywell’s approach to this problem is that its researchers take advantage of existing hardware in the aircraft, using new software to make primary flight displays and multifunction displays (PFDs and MFDs) do a lot more work than they were designed for.

What’s missing from this picture is a head-up display (HUD) because Honeywell doesn’t see that as necessary for what it is has accomplished: safely flying to below CAT I minimums on instrument approaches.

Honeywell, which doesn’t make HUDs, has replicated HUD symbology on its PFDs, adding that symbology to a sophisticated synthetic-vision display. And using a PFD that displays synthetic vision and the HUD symbology, Honeywell has proven that pilots can safely and accurately land in weather below CAT I minimums. Further along the technology spectrum, Honeywell has added enhanced vision and combined it with the synthetic-vision display on the PFD to give pilots an even better view in poor weather conditions.

All this work is not just for fun but is aimed at certification. The first target is Honeywell’s SmartView for Lower Minimums (SVLM) technology, which is Honeywell’s SmartView synthetic vision combined with the HUD symbology. SVLM is Honeywell’s term for the ongoing effort in the avionics industry to develop synthetic vision guidance systems (SVGS) that will qualify for lower minimums.

Honeywell is seeking certification in 2017 for pilots to use SVLM to fly to 150-foot decision altitude with 1,400-foot runway visual range (RVR). This would be at a CAT I airport with a crew that, like all instrument pilots, already flies CAT I approaches (200 feet and 2,400 feet RVR or 1,800 feet with certain types of approach and runway lights). The crew would need additional training to fly the approach using SVLM, but more like one learns how to fly an ILS approach as opposed to the far more stringent training required for CAT II approaches, which mandate training every six months. CAT II approach minimums are 100 feet and RVR of 1,200 feet.

The reason that SVLM works for a CAT I ILS approach and why it makes sense is because no additional ground infrastructure is necessary. For example, GPS approaches require the addition of ground stations and more satellite capacity to verify the accuracy of GPS signals during the approach, adding to the complexity of deploying these approaches. ILS and especially CAT II systems require extensive and highly sensitive ground infrastructure. SVLM instead relies on the integrity of the airborne equipment and uses the aircraft’s onboard Laseref IV inertial reference unit, in Honeywell’s case, to monitor the quality of the aircraft’s position during the approach. This works for both ILS and GPS LPV approaches. “The future looks like less ground infrastructure and more that the aircraft can do [with its own equipment],” said Jeff Merdich, Honeywell director of commercial avionics displays, marketing and product management. “We’re trying to make it so the flight deck supports these key functions.”

According to Honeywell test pilot Sandy Wyatt, who has been deeply involved in SVLM development and flight testing, “The desire is there within the FAA” to see this technology certified and in service.

Ultimately, SVLM should be usable to even lower minimums–100 feet and 1,200 RVR–because it is easy to fly. Pilots are successfully transitioning from the head-down view of looking at the PFD during the approach to head-up and looking out the window with plenty of time to match the views inside the cockpit and outside the windshield and landing with a high degree of accuracy. “Because the display is so easy to, you can fly to CAT II standards,” said Thea Feyereisen, an engineer fellow at Honeywell Advanced Technology, Flight Safety Systems in Golden Valley, Minn.

Approach Accuracy

In flight tests of SVLM in the company’s Falcon 900, Honeywell measured a variety of parameters during more than 100 approaches. Similar tests were accomplished in a Boeing 777 proof-of-concept simulator, but in this case during more than 450 approaches.

The tests showed extremely small deviations in all categories, and all were well within applicable criteria. For example, lateral deviation during the ILS approach was 0.07 dots from the centerline, while the LPV approaches averaged 0.05. When flying with the autopilot coupled during the approach, lateral deviation was just 0.02 dots, while pilots flying manually used a small amount of additional space, up to 0.06 dots.

When looking at airspeed control, the autopilot won again, with a 1.92-knot deviation from optimum, while pilots hand-flying kept airspeed to within 2.21 knots. Two pilots who flew without the flight director cue and without the autothrottles scored vertical deviation roughly twice that when they were using the flight director and autothrottles. One pilot’s autothrottle/flight director performance was extremely accurate, just 0.09 dots from optimum, but without those tools this pilot deviated by 0.40 dots.

However, these approaches were all “with acceptable vertical performance,” according to Honeywell. Two pilots who weren’t type rated in the Falcon 900 were assessed for airspeed deviation with the flight director/autothrottle versus without that equipment. Pilot A was off by 5.42 knots without the equipment and only 1.3 knots with the equipment. Pilot B was off 3.30 and 1.62 knots respectively. The entire pilot sampling in the airspace deviation test was off 4.36 and 2.21 knots, respectively.

Honeywell has flown SVLM in the Falcon 900 to CAT II minimums with great success, demonstrating that the technology is operationally suitable for the task that Honeywell researchers have devised. But there is another technological step that Honeywell has taken to make the head-down view on the PFD even more compelling and useful, and that is called Combined Vision System (CVS).

One problem with synthetic vision is that no matter how accurate it is–and Honeywell’s Laseref VI monitor system delivers high accuracy–the view is still an animation that represents the outside world. The runway environment may look clean and dandy and in the exact right position to make transitioning to the head-up, looking-outside view easy, but what if a deer decides to amble across the runway while you’re still looking down at the PFD on your way down to 150 or 100 feet above the touchdown elevation? You might look up and be surprised that the PFD view doesn’t match the deer that’s all of a sudden in your headlights.

What if the airplane has an enhanced vision system (EVS), which typically uses an infrared sensor to display a view of the outside world on a cockpit display? That would enable you to see the deer on the runway, or thunderstorm cloud tops at night or runway lights in certain weather conditions well before the human eye can see them.

Of course, some airplanes are already equipped with enhanced flight vision systems (EFVS), which is EVS displayed on a HUD so you don’t have to look down at an MFD to see the EVS sensor output. And with EFVS, the FAA already allows descent to below CAT I minimums under FAR 91.175, provided the EFVS allows the pilot to “see” specific elements of the runway environment, then transition to natural vision for the remainder of the approach down to the runway.

CVS simply takes the EVS image and snaps it neatly into the middle of the synthetic vision view on the PFD, so the benefits of SVLM and EVS add up to something that should be just as good as EFVS. An added benefit is that the CVS view is all in color, unlike the monochrome green of a HUD.

Honeywell’s technologists have not only got SVLM and CVS running on the Falcon 900 (with a goodly amount of test equipment in back to make this futuristic tech run on the cockpit displays), but have also developed some other interesting features. One is the airport moving map, in both 2-D and 3-D views. This system–called Taxi Wizard–is designed to help the pilot see in a synthetic vision view the position of the aircraft on the airport, all pertinent signage and even a magenta line to follow to a location on the airport.

The airport moving-map system automatically transitions from the 2-D view to 3-D as the airplane slows down after landing. The 3-D view pops up, almost as if the occupant of the cockpit suddenly gets whisked up and away to view the airplane from an exocentric (bird’s-eye) perspective.

More new technology from Honeywell is its Cockpit Display of Traffic Information (CDTI), which is an implementation of ADS-B IN, blending TCAS traffic with traffic obtained via ADS-B IN.

Flying Technology

Last month, Honeywell invited AIN to fly with Wyatt and Honeywell chief test pilot Jary Engels to try out SVGS, CVS, AMM and CDTI in the Falcon 900 equipped with Honeywell’s Primus Epic flight deck.

I taxied the Falcon 900 to try out the 2-D and 3-D airport moving map (AMM) then flew an ILS 11L at Tucson using Honeywell’s SVLM synthetic vision guidance system (SVGS) and observed the Rnav 25L at Deer Valley with combined vision system (CVS) plus SVGS, which adds the better accuracy of the monitor system. On the way between Deer Valley and Tucson, I was able to see how the cockpit display of traffic information (CDTI) works.

The AMM Taxi Wizard makes moving around on the ground much easier by presenting information that the pilot needs on the synthetic vision view, whether in 2-D or 3-D (bird’s-eye) mode. Although when I look out of the windshield, airport signage isn’t floating in the middle of the taxiway as it does in the 3-D AMM, the presentation on the PFD looks completely natural and matches official signage conventions. The taxiway that we’re on is marked with a sign floating in the distance in the center of the taxiway, while crossing taxiways are highlighted by floating yellow signs with arrows pointing left or right to indicate exactly which taxiway the sign is identifying.

The idea here is that the 2-D airport map is for strategic planning, plotting out the route on the ground, avoiding hotspots and aiding overall situational awareness. The pilot can select the destination on the airport, and the AMM will draw a guideline showing the way. The 3-D map is for tactical situational awareness, to help pilots avoid runway incursions with unambiguous and easy-to-interpret depictions of signage, runway hold short gates and so forth.

After landing, the synthetic vision display automatically transitions from the airborne view to the 3-D AMM as the groundspeed slows to a specified level. The transition seems entirely natural, and so, too, is the way the 3-D AMM matches the outside world to that depicted on the synthetic vision display.

We looked at some traffic displayed on the cockpit display on the way to Tucson. Moving the mouse pointer over the diamond-shaped TCAS or arrow-shaped ADS-B traffic highlights any available information. This includes N-number, range, relative bearing, relative altitude, track, ground speed and vertical speed. CDTI is integrated into the interactive navigation (INAV) system on Honeywell’s Primus Epic flight deck, so there is no need to open a new page of information to view traffic.

I hand-flew the ILS 11L approach into Tucson to get a feel for the accuracy of the monitored SVGS and also the transition between head-down viewing of the PFD to head-up looking through the windshield. The clear weather didn’t offer a chance to evaluate SVGS without being able to see the airport through the windshield, but I did find that the inside and outside views matched perfectly, and the transition from one to the other felt natural. As we leveled off above the runway at 100 feet before going around, Wyatt had me yaw the Falcon from one side of the runway to the other while looking at the PFD, just to see how precisely the synthetic vision view matches the real world.

Flying north over Phoenix toward Deer Valley, I spent some time looking at the EVS imagery embedded in the synthetic vision display, creating the CVS view. The challenge for Honeywell designers was not only to get the colors on the EVS image to match the synthetic vision colors, but also to make sure the edges of the EVS image showing the real world outside blended seamlessly into the synthetic vision animated depiction of the real world. Otherwise CVS would look odd and pilots might find that confusing, for example, if a mountain ridge suddenly was split in two where the images join.

The CVS highlighted features on the ground clearly so I could easily pick out the heat signature of a road or Sky Harbor airport. In the top part of the EVS window, a raft of puffy clouds stood sentinel on the horizon, clouds that I could see on the PFD only because of CVS. Where the ground met the air on the EVS window, the edges of terrain features perfectly matched the edge of the terrain as depicted on the synthetic vision, adding to the realism and comfort of how the head-down view mirrored what I expected to see looking outside the windshield.

As we steered the Falcon back toward Deer Valley, the extended centerline on the synthetic vision display confirmed that we were headed in the right direction. I had moved back to the observer’s seat and watched as we slid down the approach while on autopilot, closely tracking the LPV vertical guidance, which resulted in display of a virtual PAPI with two white and two red lights on the left side of the virtual runway. A bounty of information filled the PFD: the LPV glidepath indicator, a flight path marker pointed at the touchdown point, flight director cue right inside the flight path marker, a tiny airplane symbol superimposed over the extended centerline showing any crosswind effects by how much it is pointed into the wind, radio altimeter, gear and flaps positions, and much more. I hardly wanted to look outside, and the CVS imagery on the PFD made it so there really was no need to look through the windshield until just before landing.

Once we touched down, the Falcon slowed and the 3-D airport moving map popped into view, and we taxied off the runway to Honeywell’s hangar.

The technology we flew with during that demonstration flight is still under development, although Honeywell has been working on it for a many years. In the Falcon, the test equipment installed in the cabin runs the software that drives the cockpit displays, and the test engineers had to load various configurations between each demo.

“This is all evolutionary,” said Engels. “We don’t want it to be a dramatic change. Before synthetic vision was for situational awareness only. Now it’s navigation-grade. And we’re going to a phase where we’ll get [lower landing minimums] credit. Then we’ll evolve to combined vision.”