Coverage: Americas, International, or Worldwide
Airports: Identifier, city/state, country, facility name, lat/lon, elevation, fuel service, control, approach information
VORs: Identifier, city/state, country, facility name, lat/lon, frequency, co-located DME/TACAN, magnetic variation, weather broadcast indication
NDBs: Identifier, city/state, country, facility name, lat/lon, frequency, weather broadcast indication
Intersections: Identifier, country, lat/lon, nearest VOR
Frequencies: Approach, arrival, control area, departure, Class B, Class C, TMA, TRSA (with sector, altitude, and text usage info), ASOS, ATIS, AWOS, center clearance delivery, tower, ground, unicom, pre-taxi, localizer, and ILS
Runways: Designation, length, width, surface, lighting, pilot-controlled lighting frequency
FSS: Identifier, reference VOR, frequency, usage
ARTCC: Identifier, frequency, usage
MSA: Minimum safe altitude along and in proximity to active flight plan
Approaches: Non-precision and precision approaches throughout the database coverage
SIDs/STARs: Contains all pilot/nav SIDs/STARs
Airspaces: Class B & C with sectors; International CTA & TMA with sectors; all SUAs, including MOAs; prohibited and restricted areas with controlling agency and airport
Emergency Search: 9 nearest airports, VORs, NDBs, intersections, or user waypoints; 2 nearest FSS and ARTCC frequencies
Alarms: Arrival; timers; airspace alarms at 10 minutes, 2nm, and inside SUA
Waypoints: 1,000 User Defined
Flight Plans: 20 reversible routes of up to 31 waypoints each
Frequency Display: Upper-left corner of active matrix LCD, 2-lines with active frequency above standby
Channels: 760 (25 kHz spacing); configuration for 3040 channels (8.33 kHz spacing) also provided
Frequency Range: 118.000 MHz to 136.975 MHz
Transmit Power: 10 watts (minimum)
Modulation: 70% (minimum)
Receive Sensitivity: 2.0 microvolts (hard) for 6 dB S/N with 1 kHz 30% mod.
Squelch Sensitivity: 2.0 microvolts (hard) typical
Audio Output: 100 mW (minimum) into a 500 ohm load; External speaker amplifier required
GPS: TSO C129a A1
VHF COM: TSO C37d, Class 4 and 6 (transmit) and TSO C38d, Class C and E (receive)
Receiver: twelve parallel channel receiver simultaneously tracks and uses up to 12 satellites
Acquisition Time: 12 seconds (warm), 45 seconds (cold)
Update Rate: Once per second, continuous
Planning Features: True Airspeed, Density Altitude, Winds Aloft, RAIM Availability, Sunrise/Sunset Times, Trip and Fuel Planning, Vertical Navigation (VNAV)
Interfaces: ARINC 429, Aviation RS-232, CDI/HSI, RMI (digital: clock/data); Superflag Out, Altitude (Gillham/Greycode and serial), Fuel Sensor, Fuel/Air Data
Map Datums: 124 and 1 user-defined
Unit Size: Width = 6.25"; Height = 2.65"; Depth = 11.00" behind panel, with connectors
Unit Weight: 6.6 pounds installed
Display: Color LCD
Power: 11-33 VDC
Data Storage: Separate internal battery protects stored data for up to five years
Temperature: -20°C to +55°C (operating range); -20°C to +70°C (short-term operation)
Humidity: 95% non-condensing
Altitude Range: -1,500 ft to 50,000 ft
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Garmin has provided Service Advisory 2051 for general recommendations, materials, and supplies to clean and disinfect Garmin products. Otherwise, not following the recommendations could void the warranty.
An altimeter does not measure altitude on the GNC-420. The altimeter in the aircraft measures air pressure. The altimeter is calibrated to display a certain change in altitude based on a change in air pressure. For every inch of mercury pressure change, the altimeter displays a change of approx. 1000 ft. of altitude. The GPS does not use air pressure to determine altitude and is not subject to the pressure errors in determining altitude. Therefore, the GPS derived altitude is almost always more accurate than an altimeter. Since everyone uses a pressure-based system to determine altitude, it is integral to utilize a pressure sensitive altimeter to ensure required vertical separation.
For handheld GPS receivers, database updates can be ordered and downloaded directly through Garmin's Internet site.
For panel mount GPS receivers, all database cards and computer downloads (if applicable) must be ordered through Jeppesen. Contact Jeppesen at www.jeppesen.com for more information.
The Garmin HTAWS or Helicopter Terrain Awareness is only available for Garmin WAAS GPS receivers. The added GPS integrity, quality, and performance that WAAS GPS provides is needed to facilitate the helicopter terrain functions. Therefore, an original GNS430, GNC420, GPS400, GNS530, or GPS-500 navigator must be upgraded to WAAS or "W" status before HTAWS can be incorporated.