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EVS and SVS: The future of your PFD?

By Robert Goyer / Published: Dec 23, 2010
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On the trip up, we had a chance to see how the new blended approach works. Accidents in cruise are not common, so I was a bit surprised to see just how reassuring the EVS display felt to me even in that phase of flight.

We also got to see a few interesting effects of the technology. For one, because the infrared sensors see heat, warm masses in the early evening tend to give off an eerie halo. Also, because the EVS and SVS "see" at different ranges at higher altitudes — in our case around 15,000 feet — the horizon line between the two images on the display was slightly off.

Otherwise, the way the two images meshed was remarkable, a real testimony to the accuracy and quality of Honeywell's worldwide terrain database.

The proof of the technology is in the approach and landing. After all, that is the most hazardous phase of flight.

When it was my turn at the controls, I hand-flew a visual pattern, intercepting the localizer on the ILS at Prescott. The "hand-flying" part is important for a couple of reasons.

First, the wealth of information available to you as you fly makes the notion of a scan positively antique. You don't need to learn to divide your attention between the various instruments and cross-compare their messages while you fly. Instead, you can focus on the flying and leave it at that.

This technology also makes the distinction between visual and instrument flying a very tenuous line, especially at night. With this enhancement of SmartView, looking outside the window, even sometimes when it's legally VFR, such as on our dark-night flight, gives you less visual information rather than more.

As you near the runway threshold, the look of the system changes again, this time to clear out the center of the display in order to make runway lights more obvious as you approach. Spotting those runway lights from a distance is a bit of an acquired skill. At a range of seven miles, the first few times I had to have them pointed out to me. Eventually, I got the feel of what to look for.

As we flew the long final-approach course in, the right-seat pilot, longtime Honeywell flight test engineer Sandy Wyatt, showed me just how much I liked the EVS superimposed on the synthetic vision display by turning it off. He asked me how I felt about losing the EVS, which was a roundabout way of asking how much I liked the new system — how much, as a pilot, I felt in my gut that it added to the safety equation. I simply said, "I get it. Would you please turn it back on now?" He was more than happy to oblige.

As you approach the threshold, the runway lights become obvious in the EVS. It is on short final, in fact, that the blending of SVS and EVS is most impressive. On autopilot I flew a low approach to a missed at KPRC and watched as the two systems worked together in near perfect harmony to blend their versions of the outside world. I say "near perfect" because at 115 knots and 100 feet, as we tucked the gear and went to go-around power, the computerized picture of the fast-changing runway environment was a few feet off from the EVS view along the edges of the runway, as you can see in the photo on page 63.

I went into the flight that night vaguely interested in seeing what EVS might bring to the SmartView mix. I left it feeling as though it is an absolutely vital part of the system.

The new blended-display technology is still a concept. But the overwhelmingly positive response to the system by pilots who, like me, have been lucky enough to fly it makes it look as though the blended approach is the future.

Will it replace head-up display technology? It might. Today, head up systems combine flight display information with EVS to allow the pilot, when approved, to fly to a lower decision height on the approach, down to as low as 100 feet agl. Honeywell is confident that someday head down systems, like that in the Sovereign I flew that night, will give such benefits.

One of the big questions is about the transition time from the PFD to the real world. Wouldn't it take so long to go from the instrument view to the visual that it would be harder to hand-fly the last 100 feet? The answer, based on Honeywell's early trials and my flight too, is that the transition is very easy and very natural. What you wind up seeing when you look out the window, after having flown the approach on the PFD, is pretty much what you've been seeing all along. If the system is approved for lower approaches, the added capability would go a long way toward justifying the additional expense of the system to the people who write the checks.

To pilots like me, who have had a chance to see the new technology in action, the safety benefits are clearly displayed.

If the technology gains approval, something Honeywell expects to happen within a few years, it could help cut down significantly on one of the most stubborn and deadly classes of accidents.

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