Terrain is shown in topographical color fashion with lower elevations in green changing to darker shades of brown as elevation increases. There is a color scale that shows range of elevations that each shade of color represents. The only thing missing on displays of tall mountains is a snow cap. The terrain data resolution is nine arc seconds for much of the world, though some remote areas are not surveyed at that detail. Nine arc second resolution causes some rounding of peaks or valleys on the display, but I found the resolution to be remarkable in showing the rolling small hills and valleys of what most of us think as flat Kansas farmland. The overall resolution and detail of SVT is much better than other light airplane synthetic vision systems I have flown, and impressively close to the remarkable system Gulfstream and Honeywell developed for that company's large cabin jets.
I must say that I was prepared to hate the pathway box display because I have not liked them on any other HITS display I have flown. But after a few minutes I began to appreciate the usefulness of the pathway, particularly for those G1000 installations that don't have a flight director, or for pilots who don't like or are unfamiliar with flying flight director commands.
The pathway boxes are actually rectangles that represent a block of airspace 700 feet wide and 200 feet tall. The size of the boxes shrink on an ILS or LPV approach as you near the runway, and in no case will the boxes be larger than half-scale CDI needle deflection. The boxes are spaced 500 meters apart and are presented in magenta if the guidance is GPS based or in green if the source is VOR/ILS. The box colors match the colors of the course information shown on the normal instruments. When you are on course you see four boxes. As the one fades from view as you fly through it, a fourth one appears 2,000 meters ahead. The spacing shows progress at slow speeds, and is not too distracting at high speeds. When not on course -- intercepting a course, for example -- there is no limitation on the boxes in view.
When approaching a course to intercept, the boxes appear as a string of dots in space placed at the desired altitude above ground. As you shallow the angle of intercept you can see they are boxes, not dots, and begin to maneuver the flight path marker into the boxes. It's important to understand that it is the flight path marker, not the center airplane symbol on the PFD, that must fly through the boxes to stay on course. I followed the boxes around a holding intercept, a missed approach turn back to a holding fix and on a T-bone GPS type of approach. The spacing on the boxes -- at least at Skylane speed -- made it easy to see how the next box was moving left or right, up or down to fly curved procedures.
Flying the pathway boxes was not any easier for me than flying the V-bar flight director commands, but then I have many thousands of hours behind a V-bar. But the pathway boxes are visually expanded so they actually command a very precise path through the air. Just as when flying the expanded scale of a HUD, or the flight path guidance of Falcon Jet's EASy cockpit, I felt like I was not being very precise because the flight path marker kept moving around in the boxes in the turbulence. But when I looked at the conventional CDI and glideslope needle they were not moving. Having the flight path marker at the edge, or even a little outside the box, didn't cause the CDI needle to move even a quarter of its width. I think I would probably turn off the pathway markers after intercepting an ILS, for example, to remove clutter, but for terminal area maneuvering they really do work.
As you approach a runway that has been selected it appears much larger than actual scale on SVT. If it were shown in scale the runway would be a speck from 20 miles away. As the approach continues the actual runway appears on scale inside the expanded runway box, and on short final you see the runway number and the texture of the pavement of the actual runway in faithful size and perspective. Nobody would recommend using SVT for an actual zero-zero landing, but I bet I could make a survivable touchdown with it in an emergency.
Because SVT is being individually certified in each G1000 application, pricing and availability will be dependent on the airplane manufacturer. Every company that equips its airplanes with G1000 is doing its best to make SVT available as soon as possible and the upgrade can be performed at Garmin dealers with no hardware changes. Diamond was first to announce an SVT price of about $10,000 for new deliveries and retrofit in the DA40, but each G1000 application is custom and unique to each airplane, so expect considerable variance in pricing.
It is tempting to believe that SVT will be useful only when flying near mountains because they provide all the visual drama on the display and are an obvious hazard. But the flying reality is that a 500-foot high hill is equally deadly if you are at 400 feet. Flying in clouds, reduced visibility or darkness is always more risky than flying in visual conditions because our natural orientation facilities are inhibited. SVT returns a pilot to a more natural world, one where our instincts can backup our procedures and provide reassurance that we are really headed for where we want to go. I find the capability, clarity and usefulness of SVT amazing at any price, but that such capability is possible for piston singles is something I never expected to see. And, most telling, when you push the button that turns the SVT images off and you are looking at only a brown and blue presentation of the PFD, it feels like you just flew into a cloud on an otherwise nice VFR day.
