Part #:

Model: GNC-420

Garmin - Color GPS/Comm
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Part Number :


GNC 420
 

PLEASE NOTE: This item has been superseded by GNC-420W
FEATURES
  • IFR GPS with color moving map & 10-watt Comm
  • Jeppesen database (front-loading data card) contains all airports, VORs, NDBs, intersections, FSS, Approach, SIDs/STARs, and SUA information
  • Offers enhanced situational awareness with relation to cities, highways, railroads, rivers, lakes and coastlines
  • Use of color separates land data, terminal areas, route, and approach information for easy pilot scanning
  • TSO C129a certified for non-precision approach
  • Frequency nomination feature loads Comm frequency into standby with touch of button
  • Self-contained unit with annunciation included in one box eliminating need for separate annunciation unit
  • XM WX satellite weather service via GDL 69 available
SPECIFICATIONS

Jeppesen Database

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

Safety Features

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

User Customization

Waypoints: 1,000 User Defined

Flight Plans: 20 reversible routes of up to 31 waypoints each

VHF COM Performance

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

Certifications

GPS: TSO C129a A1

VHF COM: TSO C37d, Class 4 and 6 (transmit) and TSO C38d, Class C and E (receive)

GPS Performance

  • Position: 15 meters (49 feet) RMS*, 1-5 meters with differential corrections
  • Velocity: 0.1 knot RMS steady state
  • Velocity: 999 knots
  • Acceleration: 6g's

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

Accuracy:

Dynamics:

Nav Features:
      Pilot-defined Course Selection and Waypoint Hold, Closest Point of Approach, Departure and Arrival Frequencies, Approach Navigation using published approach procedures stored on NavData card, Terminal Navigation using SIDs/STARs from NavData card

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

Physical Specifications

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

Environmental

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

 

011-00506-00
- Color GPS/Comm (28V)
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REQUEST SV EXCHANGE REQUEST
011-00506-10
- GPS/Comm
Price Condition Status
REQUEST SV EXCHANGE REQUEST
011-00506-30
- Color GPS/Comm
Price Condition Status
REQUEST NEW EXCHANGE REQUEST

Click on a question below to see the answer. If you have a question about this model that is not answered below, please contact questions@seaerospace.com

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.

  • Cleaners containing ammonia will harm the anti-reflective coating on many Garmin aviation display lenses.
  • Disinfectant with a solution of 70% isopropyl alcohol that does not contain ammonia is preferred. Solutions of up to 91% isopropyl alcohol are also acceptable.
  • Clean the display lens using a clean lint-free cloth and a cleaner that is specified as safe for anti-reflective coatings.
  • For other exposed surfaces such as knobs, buttons, and bezels, a damp cloth with soap and water is acceptable.
  • Bleach-based cleaners, ammonia-based cleaners, or other harsh chemicals on any surface are not recommended.
  • Remove all soap/soap residue to prevent buttons and knobs from gumming up or becoming slippery.
  • Many aviation products are not rated as waterproof. Spraying or wetting the units to the extent where moisture could go beyond the exterior surfaces could damage the unit.

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.

As a dealer for an Original Equipment Manufacturer (OEM), it is required to commit to a dealership agreement. Garmin's dealer agreement states that certain TSO'd products must be installed by the dealer for the factory warranty to be valid. There are generally 2 reasons for this policy. First, the OEM wants to minimize their liability risk by assuring their equipment is installed by factory trained and knowledgeable technicians. Second, Garmin wishes to maintain their products integrity by making sure the product is installed and operating properly so the customer is satisfied with the performance. Avionics installations and interfacing can sometimes be very complex. It is very important that pilots, aircraft owners and operators ensure installations are performed by skilled, experienced technical personnel to provide the safest flying environment and experience.
There are quite a few changes and issues that need to be addressed in reference to upgrading/modifying a GNS-400/500 series unit to include WAAS capability. It is strongly suggested that you go through an authorized Garmin dealer who has performed this modification/upgrade previously.

There are several installation and certification issues including review of the STC approval from Garmin. This STC includes appendices detailing the approved equipment that can be interfaced to the WAAS capable units as well as approved installation diagrams for these interfaces.

The upgrade from Garmin includes the necessary updating of the unit, WAAS antenna, and new IFR-W Jeppesen database. The existing GPS antenna is replaced with the WAAS antenna. This WAAS antenna utilizes the same mounting holes however it should be noted that it is physically larger than the original GA-56 GPS antenna that was included with all GNS-400/500 series units. Also, in regards to the antenna installation, RG-142B or RG-400 coaxial cable must be used.

The 400/500W units with WAAS capability offer many new features and enhancements over the classic models. Some enhancements include WAAS enable GPS antenna, receiver, and software. The 400W/500W series units comply with WAAS TSO C146a and include hardware upgrades with a faster micro-processor. A terrain database for terrain awareness is included a standard feature. Most importantly, the WAAS GPS receiver allows pilots to use the GNS-400W/500W units for primary navigation and vertical guidance for LPV, L/VNAV, and LNAV+V approaches.

For a complete summary of the feature changes and enhancements, click Here.
The hardware and software upgrade for WAAS to the classic GNS-400/500 series navigators adds FAA TSO C146a Gamma-3 certification. This upgrade and certification enables pilots to fly Lateral-Precision with Vertical guidance approaches and receive GPS navigation via the Wide Area Augmentation System.
Yes, some are noticeable and some are minor. The WAAS upgrade to the GNS-400/500 series units WAAS upgrade includes a faster 5Htz update rate on the GPS signal. Therefore, the GPS receiver in the unit is extracting GPS information 5 times per second instead of 1 time per second as with original units.

If the terrain advisory feature is installed on the 400/500 series unit, then the terrain information will have a higher resolution.

When the GDL69 datalink is interfaced to the WAAS upgraded units, the weather will cover the entire USA instead of just 250 miles. METARS are included in the waypoint section making it easier to see weather information for a particular destination. Installations using the GDL69A with music will now be able to view the title and artist name on the GNS display.

Lastly, the WAAS upgrade provides the ability to fly curved flight paths with a roll steering autopilot for pilots who wish to utilize DME arcs or full approaches.

The WAAS upgrade for the GNS-400/500 series units is not a 'plug and play' upgrade. There are several installation, certification, and operational subjects that must be adhered to before a proper WAAS upgrade can be completed.

For aircraft with dual GNS-400/500 series units, both units must be upgraded for the crossfill function to operate. A WAAS upgraded 400/500 series unit will not crossfill to a non-WAAS 400/500 series unit.

One subject that many people upgrading to WAAS may overlook involves the GPS navigators distance from the pilot's primary field of view. The original GNS-400/500 series installation guidelines only provided general suggested guidelines for the distance of the unit from the pilot's primary view. Page 2- of the WAAS GNS-400/500 installation instructions is very specific in regards to the suggested guidelines for this distance. The left edge of the GNS unit should be no more than 11.8 inches from the centerline of the pilot's field of view. The 500 series units allow 12.1 inches. Vertically, the top of the GNS unit cannot be lower than the bottom edge of the primary flight instruments. If these measurements are exceeded then an additional annunciator may need to be installed near the pilot's primary field of view.

There are several wiring changes that need to be made to make the Bendix King KAP-140 / KFC-225 autopilots and original Sandel SN3308 EHSI completely compatible with the WAAS upgraded units. Certain features regarding proper navigation deviation will not function properly unless wiring changes are made in the aircraft. In addition, aircraft with more recent glass cockpit technology (e.g. EX5000 and G1000) have not been completely addressed for the WAAS upgrades.

In order to ensure that you receive the most accurate and realistic quotation for this WAAS upgrade, we strongly suggest that you contact our Installation Department for further assistance.

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.

Yes, the Garmin GNS400/500 systems meet RNP5 airspace (BRNAV) requirements of AC 90-96 and in accordance with AC 20-138, and JAA AMJ 20X2 Leaflet 2 Revision 1, provided it is receiving usable navigation information from the GPS receiver.

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.

There is some confusion in the avionics industry relating to the various terms used for terrain awareness, terrain advisory, and terrain alerting systems. Not all terrain systems are certified to Class A or B TAWS standards specified in FAA TSO C147b. If a terrain system is certified and approved to FAA TAWS standards, then the manufacturer will specifically use the term "TAWS" and/or "Class A/B TAWS". In most if not all cases, the term "terrain advisory" should not be understood to indicate "TAWS" or imply the product meets TSO C147b.
Newly Overhauled parts obtained from Garmin are designated with an N in their part number. This usually follows the 010- in the part number. As with most Garmin 010 part numbers, the N part numbers are for ordering purposes only and do not actually appear on the dataplate of the unit.