Other features include texturing of geographical features, gridlines to confer a sense of scale that's hard to capture otherwise and Honeywell's patented Range Rings, which show the distance from the airplane to lines drawn on the terrain represented in the display. (This last feature I have found incredibly handy for radio calls. One look at the display and you can quickly estimate your position.) You even get your course line superimposed upon the terrain, to further aid in situational awareness.
Also remarkable is the way that Honeywell has been able to integrate its terrain warning system onto the synthetic landscape of SmartView. As the airplane encounters terrain that is within the warning range of the EGPWS, the computerized terrain lights up in yellow or red, making it immediately clear just where the high terrain is.
Enhanced vision also validates the synthetic vision display. Of course, that display is already validated by a variety of other nav indicators, but the enhanced vision is the one that's immediately apparent and that can't tell a lie. It's a live picture of what's out there. In a way, it's like peeking out the side of the hood on a practice approach and seeing the runway right there where it's supposed to be. All it takes is a quick look to reassure yourself that you're in the right place. In that way, enhanced vision feels a bit like full-time cheating, but with all of the good effect and none of the stigma.
There are several benefits that EVS adds to the mix — the texture and perspective in the runway environment as you near the threshold — that synthetic vision has a hard time emulating. Most importantly, it typically lets pilots see the runway lights much earlier than they could with the naked eye alone.
Merging Two Visions: EVS and SVS
If Honeywell had a big challenge superimposing synthetic vision onto its PFD, imagine the challenge of superimposing yet another technology onto that. But that's just what it's done, and very successfully, with the new display. Honeywell's Chad Cundiff, who leads the blending program, says that combining the two systems brings users "the best of both and the worst of neither."
I flew the system with a group of other journalists out of the company's Deer Valley, Arizona, facility in its Cessna Sovereign. It was an eye-opener.
Because the days were still long when we made the flight, we didn't launch until past 8 o'clock, when it was dark and the EFVS would have its work cut out for it.
On taxi the effect was stunning. When you're on the ground, the EVS display expands to take up a larger area on the screen, allowing you to see real, live images of what's out there. As we headed up the parallel to take off on Runway 25L, we could see the entire taxi environment as we made our way. We got an interesting surprise as we neared the turn to the active when a bird flew by in the dark of night but lit up bright as day in the eyes of the EVS sensor.
As we turned onto the runway and began our takeoff run, the EVS display remained large in the PFD, enabling us to clearly verify our track and, perhaps more importantly, to ensure that there were no unknown vehicles, such as a disabled airplane, on the runway. Without EVS, at an uncontrolled field at night, it might be impossible to discern the presence of such a hazard until it is too late to avoid a collision.
I had always assumed that, when EVS finally got superimposed onto synthetic vision, a step that has been talked about for years, the EVS picture would somehow be blended with the entire SVS image, perhaps by making it just translucent enough that you could see the general outline of the computerized image behind the EVS image.
But that's not how Honeywell did it. Instead it dedicated a small part of the display — just the very center of it — to the EVS image. This, like many great ideas, makes such good sense when you think about it that you wonder why it didn't occur to you right away. After all, EVS is there for you to see what really matters most, and that is the airport to which you're inbound. Synthetic vision works fine for the big picture.
Black Hole Approach
The plan was to fly up to Prescott in the mountains to the north and fly multiple approaches to that airport. On approach there at night, there are very few visual references on which to rely, making it a challenging approach even in clear conditions, like those we encountered on our flight.