Garmin Ups the Ante
in Panel-Mount Avionics
by Fred George
Garmin's new GNS 430, which made its debut at the 1998 Aircraft Electronics Association convention in Orlando, arguably is the firm's most significant avionics product since it announced the GPS 150 AVD in 1991.
The GNS 430 combines a 10-watt output, VHF communications transceiver, VHF navigation and UHF glideslope receivers, plus a 12-channel GPS receiver. With all those features, the radio initially might seem like the newest gimmick intended to lure kit builders. The GNS 430, though, is an upper-end avionics box intended to be installed in high performance piston singles and twins, and slated for retrofit into entry level turboprops and jets.
The com transceiver, along with the nav, glideslope and GPS sensors, will be TSOed. The software will meet DO-178B Level B integrity requirements. The box will pass the trial-by-water-and-fire gauntlet of DO-160C. The GPS receiver will be both WAAS and LAAS compatible.
FMS makers take note. The GNS 430, which will be priced at under $10,000, will offer many of the same features as lateral nav FMSes priced at $40,000 and higher. For example, the GNS 430 will provide both course deviation and optional roll steering outputs to the aircraft's flight guidance system. That will enable the GNS 430 to provide lateral guidance for virtually all ARINC 424 lateral navigation procedures, including IFR arrivals, departures and approaches, that are defined by lat/long waypoints, plus provide holding pattern, arc and procedure turn guidance.
Vertical navigation functions will be more limited. The GPS navigator will have a single waypoint, advisory VNAV function, similar to the current generation of Garmin's GPS navigators, It will be up to the pilot, as a result, to compute the appropriate descent profile while ensuring adequate terrain clearance. Don't expect the first versions of the box to provide multi-waypoint VNAV or complex, combined heading, altitude and course procedure guidance offered by TSO C115b 3D FMS navigators. The display, however, will have a vertical profile view to help pilots manage the descent.
The GNS 430 probably will weigh between six to
eight pounds. Later, it could evolve
into many different sizes, some of which will offer
many more capabilities.
Many boxes offer some of the same features as the GNS 430, but it's the integration of the com/nav/glideslope/GPS functions that will set Garmin's latest product apart. The box, for example, automatically will nominate the appropriate VOR and localizer frequencies for your selection as VHF navaids. It will send the correct ATIS, approach, clearance, tower or ground control frequency to the com radio at the touch of a button. In essence, the GNS 430 will not only offer the automatic GPS to NAV functions of a high-end FMS, it also will automatically tune your com radio like current-generation com/GPS panel-mount radios.
Based on our initial impressions, the GNS 430 should be easy to use. We found it easy to understand the functions of the dual, concentric knobs, buttons and switches on the prototype box even though we had no operating manual.
The system will have a 16-color, active-matrix LCD that measures approximately two inches high and three inches wide, with a resolution of 128 by 240 pixels. The screen can display both a map and window insets. The window on the left side of the screen, for example, displays the standby and active com and nav frequencies. The frequency being tuned is highlighted by the use of reverse video. A menu window (not shown), on the right side of the display, will be used to select various flight planning, nav procedures and advisory vertical navigation functions.
Similar to some of Garmin's current products that have monochrome LCDs, the GNS 430's 16-color LCD map graphics will make it much easier to use the units that have only alphanumeric displays. The box will be able to map out the procedure being flown, thereby keeping the flight crew in the loop between the sophisticated electronic navigator and the aircraft's flight control system.
How useful is the map graphics feature? Imagine this: You're flying the outbound course of a procedure turn that involves a 45-degree cut after one minute, followed by a 180-degree heading reversal after another minute to intercept the inbound course to the final approach fix. If you're trying to interpret a rapid-fire sequence of highly abbreviated alphanumeric characters on the display during this maneuver, it could be easy to become disoriented. However, it would be simple to monitor system performance if all you have to do is watch map graphics.
In addition to navigation chart graphics, the GNS 430 will have a cartography database that will allow the pilot to selectively display geopolitical boundaries, federal interstate highways, state routes, major local thoroughfares, plus railroads, rivers, coastlines and lakes.
The cartography database is not a gimmick. Just ask anyone who, when on approach for landing, has ever had to differentiate between two adjacent airports with similar layouts, such as San Diego-Brown Field and Tijuana General Rodriguez, or El Paso International and Biggs AAF. A moving map display with cartography can prevent misidentification of the intended landing facility.
The LCD should offer good viewability in bright ambient lighting conditions. Similar to the latest generation of flat-panel EFIS displays, the GNS 430's LCD will be backlighted by high-intensity, cold-cathode fluorescent tubes. Garmin's choice of colors for symbols and graphics will be guided by TSO C113, the standard for EFIS displays.
The GNS 430, designed as the first in a line of new products, has plenty of growth potential. The nav receiver, for example, can be modified to receive local area differential GPS corrections broadcast by means of a VHF nav band datalink and feed them to the GPS for two-meter, 3-D navigation accuracy. Installers will be able to link pairs of later versions GNS 430 boxes so that flight plans can be cross loaded between the boxes.
Garmin also is talking with plenty of other avionics firms about possible interfaces. Probable links include DME radios, primary flight displays, weather detection equipment, plus other nav sensors and systems.
Initially the GNS 430 will be packaged to occupy the same panel area as a KX-170B/175B nav/com radio, but with a shorter length. It probably will weigh between six to eight pounds Later, the GNS 430 could evolve into many different sizes, some of which will offer many more capabilities. A Dzus rail version, for example, is slated for early development.
It's not hard to imagine that Garmin could stretch the system to accommodate a much larger display, additional controls and more internal room for expansion slots in the chassis. As a result, a full-function MFD could be based on the design of the GNS 430.
The first production models only will be configured for a 28-VDC power supply. An internal fan will help dissipate the heat generated by the GNS 430's 30-watt power consumption. External cooling is highly recommended. Interfaces will include RS-232 and RS-422 serial ports, ARINC 429 (GAMA standard), left/right analog course deviation, optional analog XYZ roll steering, encoded or greycode altitude, and some basic fuel flow sensor links. Garmin also plans to offer a wide variety of optional digital and analog interfaces, thereby helping to cure one of the perceived shortcomings of past product offerings in the upper-end market.
The GNS 430 is no small milestone for a nine-year-old, mid-west upstart founded by Gary Burrell and Min Kao, a couple of senior management engineers that emigrated from AlliedSignal General Aviation Avionics. But, pushing into the technological frontier has been one of Garmin's strong suits. In the last decade, the firm developed the first GPS to earn TSO C129 A1 approach approval. Garmin was one of the first avionics manufacturers to develop a fully TSOed GPS/com radio. The company also developed a clean-sheet, solid-state transponder. And all of these products were priced below those of the top competitors.
Garmin is likely to earn serious consideration from a wide range of potential airframe suitors. The era during which airframers offered only one brand of avionics as standard equipment in their light aircraft may be coming to an end. If Garmin gains an entry-level entree into the OEM air-frame market, don't expect Burrell and Kao to become complacent with their new-found success. Technology development will remain a primary objective at Garmin. Now that Burrell and Kao have upped the ante in the piston-engine aircraft avionics market, they intend to raise the performance-to-price ratio expectations of upper-end, business aircraft avionics buyers.
This article was re-printed from:
Business & Commercial Aviation
Magazine
June, 1998 Edition