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Part# 11-17439
MFR Model# 010-02232-51


LPV Approaches and Comm, Priced for Your Aircraft

  • Slim, all-in-one touchscreen GPS navigator and Comm radio for Part 23 Class I/II aircraft (weighing less than 6,000 lbs) and experimental/amateur-built aircraft
  • Take advantage of WAAS GPS navigation with LPV approaches, which offer minimums as low as 200’ to greatly expand your operational capability
  • Built-in 10-watt Comm radio with 25 kHz or optional 8.33 kHz channel spacing (with GNC 355A) plus standby frequency monitoring and automatic frequency identification
  • Pairs with select Garmin flight displays, or integrates directly with your existing course deviation indicator (CDI) for cost-effective installation¹
  • Visualize your entire flight plan, including departures, arrivals, instrument approaches, holding patterns and more on a rich, dynamic global moving map
  • Wirelessly transfer flight plans and stream weather, traffic, GPS position and backup attitude via built-in Connext® technology to the Garmin Pilot™ app and more
Big capabilities come in a small package with the GNC 355 navigator. With its bright, clear high-resolution touchscreen display, you can have the advanced navigation functions you’ve always dreamed of — along with modern Comm radio capabilities. Entering flight information is a cinch, and accessing every function is fast and easy. It’s equally at home in certificated aircraft or an experimental aircraft. And it’s the same 2” height as older navigation equipment and can allow you to keep the composite legacy CDIs already in your aircraft to minimize installation cost¹. That makes GNC 355 the smart, affordable way to add next-generation navigation to your favorite airplane.

Perfect Touch

The moment you power up GNC 355, you’ll see a familiar Garmin homepage on the 4.8” display, which puts the most important functions within only a few touches. Navigate to dedicated pages for the moving map, traffic, terrain, nearest airports, flight plan, procedures, waypoint information, utilities and more. With shortcuts available to the flight plan and Direct-to functions on almost every page, navigation features are usually just a tap away. Use your finger to pan and zoom on any map, traffic and terrain page. Enter waypoint data with the on-screen keyboard. And touch the home button to get you back to the main page at any time.
For added control stability in flight, a shelf across the lower edge of the display serves to steady your hand in smooth and turbulent flight conditions. And if you prefer traditional controls, the concentric knobs provide yet another way to control many of the GNC 355 navigator’s functions.

Intuitive Navigation

With GNC 355, building and modifying flight plans is simple. As you enter waypoints, our FastFind feature automatically begins searching for the nearest identifier as soon as you start typing, so — in most situations — a press or two reveals just what you were thinking. You can also create holds, insert Victor airways and corresponding exit options and add departures, arrivals and instrument approach procedures. Additionally, you can edit your route using the map screen; a handy "rubber band" feature lets you grab any leg of your flight plan route and move it to accommodate a deviation or ATC amendment to your flight plan.

A variety of dynamically drawn and displayed maps provides situational awareness and context to the flight plan by highlighting visual reporting points, navaids, SafeTaxi® diagrams and hazards such as obstacles, power lines and terrain. Plus, the Smart Airspace™ feature automatically highlights airspace close to your current altitude and de-emphasizes airspace away from the current altitude.

Advanced Approach to IFR

The SBAS/WAAS-certified GPS receiver can allow you to fly GPS-guided LPV glidepath instrument approaches down to as low as 200’, greatly expanding your operational capability. You can also access localizer performance (LP) and all area navigation (RNAV) approaches. Precise course deviation and roll steering outputs can be coupled to our GFC™ 500 and GFC 600 autopilots as well as select third-party autopilots so that IFR flight procedures such as holds, NextGen radius-to-fix (RF) legs and missed approaches may be flown automatically. In addition, the GNC 355 navigator lets you create and execute custom holding patterns over an existing waypoint or user-defined waypoint.

Plus, when operating in VFR conditions, GNC 355 can provide advisory vertical approach guidance based on a published glidepath angle or a 3-degree approach glideslope from the runway threshold, while considering terrain and obstacle clearance. With this advisory guidance, you’re able to fly more consistent, precise vertical glidepaths into a variety of airfields.

Powerful Comm Capabilities

GNC 355 offers 10 watts of transmission power with 25 kHz frequency channel spacing or 8.33 kHz channel spacing options (GNC 355A), and it incorporates a number of functions that can save you time and effort. Using the onboard frequency database, airport, weather, center and FSS frequencies are easy to find and can be loaded to standby by simply tapping them from the airport information or flight pages. Recent, nearby and saved frequencies are easy to access, too. And to help you make sure you are talking to the right controller, GNC 355 automatically displays the station’s identifier right below the frequency, e.g., KIXD ASOS or CHICAGO ACC.

With the standby frequency-monitoring feature in GNC 355, you won’t have to worry about missing an ATC call or other critical transmission. The GNC 355 navigator allows you to listen to ATIS without leaving your assigned ATC channel. Swap your active and standby frequencies with a single screen touch. Press and hold the frequency optional remote transfer key to automatically set the emergency frequency as your active radio channel.

Add ADS-B Traffic and Weather

When paired with dual-link Garmin ADS-B solutions, such as our GTX™ 345 series transponder or GDL® 88 universal access transceiver, GNC 355 can display ADS-B traffic targets as well as subscription-free ADS-B weather data in the U.S. Or you can opt for the GNX™ 375 navigator, which offers similar GPS navigation capabilities as GNC 355 but includes a transponder for ADS-B “Out” and “In.” The ADS-B weather link provides in-flight access to animated NEXRAD imagery, METARs, TAFs, winds and temperatures aloft, PIREPs, NOTAMs and more.

When equipped with a compatible ADS-B solution, visual alerts help you recognize and avoid potential conflicts in busy airspace. Our patented TargetTrend™ relative motion technology offers a faster, more intuitive way to judge the direction and closure rate of intruding targets in relation to your aircraft’s position. For example, if traffic is ahead of you and travels along the same track but at a slower rate, the motion vector points opposite of its indicated direction of flight to show you are overtaking the traffic. And, at the start or end of each flight, TerminalTraffic™ technology provides the most comprehensive picture of ADS-B equipped aircraft and ground vehicles in the airport environment. ADS-B equipped aircraft in-flight are easily distinguished from ground vehicles and taxiing aircraft, which are displayed using distinct colors and symbols. All information is presented on a simple, easy-to-understand SafeTaxi diagram with reference to runways, taxiways, hangar locations and more.

Cockpit Integration

The GNC 355 navigator interfaces with Garmin flight displays, including G3X Touch™ (experimental and certified), G5 (experimental and certified), G500/G600, G500 TXi/G600 TXi as well as select third-party displays¹ to provide navigation outputs. It’s also compatible with many older, composite-input based CDIs — allowing you to keep your existing CDI and have an easier, more cost-effective installation¹.

And for even more convenience, you can use the built-in Connext technology to stream information between GNC 355 and compatible Garmin portables and mobile devices running the Garmin Pilot or FltPlan Go apps. You can create flight plans at home and upload them at the airport. And you can stream GPS data, backup attitude information (from the built-in AHRS) as well as traffic and weather to your mobile device or Garmin portable, making them even more useful cockpit companions.²

Plus, our optional Flight Stream 510 installs in the memory card slot of GNC 355 to enable our Database Concierge database transfer and management capabilities via our Connext gateway. At home, you can download selected databases onto your mobile device by using the Garmin Pilot app. Then, once you get to the airport, Flight Stream 510 will automatically establish a wireless connection to the Garmin Pilot app and upload the databases from your device to your GNC 355 in minutes.

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    Physical and Performance

  • TSO applicability: C128a; 2C128; C146e Class 3; C157b Category 1; C165a; C169a Class C, E, 4, 6; 2C169a Class C, E, H1, H2, 4, 6; C195b Category B1, B3, B5, B7
  • Display size: 4.8" (122.5 mm) diagonal
  • Display resolution: 732 pixels (W) x 240 pixels (H)
  • Unit bezel height: 2.02" (51.0 mm)
  • Unit bezel width: 6.25" (159.0 mm)
  • Unit depth with connectors: 11.23" (285 mm) (measured from face of aircraft panel to rear of connector backshells)
  • Unit weight: 3.3 lbs (0.6 kg)
  • Maximum altitude: 35,000 ft
  • Input voltage range: 9 VDC - 33 VDC
  • Maximum display brightness: 260 fL
  • Operating temperature range: -20° C to 55° C (-4° F to 131° F)
  • Bluetooth version: 4.2
  • Number of GPS channels: 15 (12 GPS and 3 GPS/WAAS/SBAS)
  • LAT/LON position accuracy: <1.25 meter RMS horizontal, < 2 meter vertical, with WAAS
  • Maximum velocity: 1,000 knots (above 60,000 feet)
  • Position update Interval: 0.2 sec (5 Hz)
  • Frequently Purchased With
  • Customers Also Viewed


In stock

406 A Verified Purchase


January 8, 2024

Kent B Verified Purchase


July 10, 2022

I replaced my old Terra units on my 182 Skylane with the GNC355 to avail the benefits of a COM radio and GPS that drives my CDI KI209. Pros: - Very ergonomic/ Sized to fit your existing set up - Touch screen is a charm!! - Screen size is good and provides good visibility - COM usage is a breeze... Easy to switch between frequencies - GPS works great, no issues, dot on.. - Provides a lot of features that you can change with your touch screen Cons: - Updates are expensive, you may have to go for a yearly option, but still high on price based on what package you choose. Overall a good combination for someone who needs a GPS and COM in one unit.

Mahesh I
September 13, 2020

I installed one in my experimental. It works well and is connected to dual G5s. However, if you want a vertical deviation indicator on a G5 you must also connect to a GAD 29. The 355s ARINC 429 signals go through the GAD 29 and provide the VDI to the G5. Previously, I had an AERA 660 connected to the G5s and it provided a VDI through an RS 232 signal. Only another $475 for the GAD 29 and another $50 for the GAD 29 connector kit.

Fred S
April 9, 2020


Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

Q: How many RS232 Tx/Rx pairs and how many ARINC 429 tx/rx pairs does the GNC 355 have? Can the GNC 355 be connected to 2.25 mid continent cdi such as MD222-506 or MD222-406 ?

This has 3 RS232 ports and 2 ARINC ports. Per the manual you can connect to the MD222-406, but the MD222-506 is not listed.

Q: Hi I am interested in the Garmin GNC 355, I want to use it with an S Tec 50 AP and a Garmin G5. To use GPSS do I need the GAD 29 B or is the roll steering included in the GNC 355 Regards Frank

Per the installation manual, you can connect this directly to your autopilot.

Q: Can the Garmin GNC 355 be connected to the Dynon Skyview Classics CDI?

Per the manufacturer, no they will not work together.

Q: Are the GNC 355, GPS 175, or the GNX 375 ILS or localizer capable?

No, these unit are for GPS approaches only. No ILS, LOC or VOR approaches.

Q: Can the Garmin GNC 355 be tuned to the 3rd decimal?

Yes, P/N 11-17439 can be tuned to 8.33 kHz.

Q: What is the circuit breaker size for the GNC 355?

The circuit breaker size is 5 Amp 28V.

Q: Does the GNC 355 include the GPS Antenna?

Yes, This will include the GA 35 GPS antenna.

Q: After purchasing the GNC 355, how are we given access to the installation instructions without being a Garmin dealer? I assume you will be providing it or some way to down load them.

Please contact our avionics sales team after you receive the unit and we can send the install instructions PDF. We can send all manuals digitally at that time.

Q: Will the GNC 355 display traffic or weather from another Garmin device via connext or will it only display traffic/weather from a GTC 375/GDL88?

Yes, it will display traffic from the GTX 345.

Q: Will the Garmin GNC 355 built-in Connext technology allow bluetooth connection to ForeFlight?

No, at this time, the unit will not allow Bluetooth to connect to Foreflight. Garmin Pilot and FlghtPlan Go are the only compatible apps.

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