Monday, September 1, 2008
Flying by visual reference—regardless of the visibility
|Over the past decade, new technology that promises to make instrument flying almost as easy as (and arguably even safer than) flying visually has been introduced into the general aviation (GA) fleet. Synthetic vision takes the idea of an artificial horizon and expands it to an artificial view of the outside world, allowing pilots to fly by visual reference even in the clouds.|
Garmin G1000 With SVT
|VistaNav, now a Honeywell Bendix/King product, offers synthetic vision on a portable device.|
Over the past few years, Garmin has had a major hit with its G1000 glass panel. From a standing start, the product put the Olathe, Kans., GPS vendor into first place among glass-panel avionics makers (with more than 5,000 installations at this writing). In April, Garmin announced a synthetic vision upgrade, which puts color-coded terrain, obstacles and runways on the PFD. Under an experimental license, the G1000 with Synthetic Vision Technology (SVT) initially flew in a Cessna 182; it’s now FAA-certificated in Diamond’s DA40 and as part of the new Cirrus Perspective glass panel for the SR22-GTS.
According to Garmin Director of Flight Operations Tom Carr, SVT consists of three major components. First, synthetic terrain derived from the TAWS database is displayed on the PFD and includes both terrain and obstacles. Second, a flight-path marker (displayed as a green circle with fins) shows how you’re going through space, taking into account wind, based on the aircraft’s attitude and heading reference. “You need something like that with synthetic terrain—if not, you’d misunderstand where you’re pointed,” says Carr. “It can be used to crab to a landing, with no outside view. In pitch, it shows where you’re going, as opposed to where the nose is pointed—so, for example, in a slow climb, it will show whether or not you’re going to miss terrain.” SVT’s third element is called Pathways, which is Garmin’s implementation of HITS. It displays rectangles that are 700 feet wide and 200 feet high, centered on the selected flight path and based on the terrain database. Unlike most other people we’ve spoken to about synthetic vision, Carr doesn’t buy into the notion of using Pathways (or any HITS implementation) as a primary form of guidance because of its sensitivity. Instead, Carr strongly recommends flying with guidance from a flight director, if the aircraft is so equipped (as are both the DA40 and SR22-GTS).
|With SVT enabled, the G1000 PFD immediately indicates that the flight path will not clear high terrain (left). Even if SVT isn’t enabled (right), the same high terrain is shown on the G1000 MFD, but the pilot has to look at the MFD to see it.|
Carr sees Pathways mainly as providing situational awareness: One glance tells you immediately whether you’re on course. Obstacles and traffic get larger as you get closer; they also change color, becoming yellow when they begin to present a possible threat and red if you get too close. And the color-coded terrain display makes it immediately obvious if your flight path will lead you to an unintended landing. According to Carr, “Just flying along at cruise altitudes, SVT doesn’t make that much difference; but it’s really neat in low-visibility conditions. IFR, night, hills and unfamiliar airports all benefit from it. Essentially, if you want it to work, it just does. For the vast majority of flights, you’ll never press a button related to SVT. Just put in the flight plan, and you’ll get lateral guidance from the flight plan; add vertical guidance from the approach or altitude preselect.” During development, Carr told us that some pilots asked for a quick way to turn off the Pathways display during final approach; this can be done using soft keys on the G1000 PFD bezel, which also allow you to selectively disable other synthetic vision functions—indeed, you can turn them off completely and revert to standard blue-over-brown PFD functionality (though after flying with SVT, it looks awfully bare).
Because Garmin licenses the G1000 to aircraft manufacturers, it doesn’t control pricing, but Carr told us that he expects it will be “very attractive.” Diamond offers SVT as a $9,995 option on the DA40, while Cirrus offers it as part of the $48,000 Cirrus Perspective package (including larger displays) on the SR22-GTS. Cessna has announced plans (but not pricing) to offer SVT on all of its G1000-equipped aircraft, beginning with the Citation Mustang, and Garmin itself expects to offer SVT on its G1000 upgrade to King Air C90 aircraft next year. For more information, visit www.garmin.com
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