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new garmin gnc355


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We have a GNC 355 and it's a nice unit.  We kept our 430W and did not really see the need for a second backup ground-based nav radio.  Approaches we fly are now are GPS just about 100% of the time unless there's an outage.

The GTN 650/750's provide a ground-based nav radio (VORs, ILS, etc) and are also capable of using Garmin's VNAV feature.  Those are the only functional differences between a GTN and the GNC 355. 

We didn't have VNAV before so I don't know what I'm missing.  I've heard it's nice.  As I understand it, It allows you to program altitude at a certain fix in your flight plan and let your autopilot take you up or down without having to change the altitude manually, e.g. while flying an arrival or SID.  Did not seem worth the extra cost of going with a GTN vs GNC but your experience may vary.

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13 hours ago, Nukemzzz said:

I’m getting quotes on the same with G5’s now. I don’t see how the GTN 650 provides me with anything that I need over the 355. Have you flown it yet?  How do you like it?  Would you recommend it to a friend?

I installed dual G5's along with a GNC355 under supervision. It is a great unit. The menus are easy to navigate and the resolution on the screen is very crisp. I would and have recommended it to others.

There is plenty of debate about whether or not you should keep a NAV with ground based capabilities (VOR/ILS) in addition to something like the GNC355 which is GPS only. I'm not going to advocate either way on it, although I opted to keep the Garmin SL-40 and ditch the Narco Mark 12D. That limits me to GPS approaches.

The GNC355 is a TSO-C145c GPS Navigator. Per the installation instructions for IFR flight with the GNC355 you must have "A second GPS navigator, VHF navigation radio, or VHF COM radio with separate circuit breaker(s) and connections(s) to ground from the GNC355."

If you do not have ground based NAV in the panel you can still file GPS at both your primary and alternate destinations with some limitations. They released this back in 2013.

  • 3) Operators of aircraft with TSO-C145() and TSO-C146() navigation systems may utilize GPS-based IAP at both the destination and alternate:
    • a) That are approved to conduct GPS-based IAP under OpSpec/MSpec/LOA C052.
    • b) Must review appropriate Aeronautical Information Services (AIS) and NOTAMs for WAAS service outages. (Reference Advisory Circular (AC) 90-107, Guidance for Localizer Performance with Vertical Guidance and Localizer Performance without Vertical Guidance Approach Operations in the U.S. National Airspace System for more details). In the event of a WAAS failure, WAAS avionics revert to unaugmented GPS functions and operators without baro-VNAV should follow guidance in subparagraph G1) above.
    • c) At the alternate, if not equipped with baro-VNAV may only plan to LNAV (or circling) MDA(h).

https://www.faa.gov/documentlibrary/media/notice/n_8900.218.pdf

It has since been updated in the AIM, page 1-1-34.

https://www.faa.gov/air_traffic/publications/media/aim_basic_w_chg_1_2_3_dtd_12-31-20.pdf

Pilots with WAAS receivers may flight plan to use any instrument approach procedure authorized for use with their WAAS avionics as the planned approach at a required alternate, with the following restrictions. When using WAAS at an alternate airport, flight planning must be based on flying the RNAV (GPS) LNAV or circling minima line, or minima on a GPS approach procedure, or conventional approach procedure with “or GPS” in the title. Code of Federal Regulation (CFR) Part 91 non−precision weather requirements must be used for planning. Upon arrival at an alternate, when the WAAS navigation system indicates that LNAV/ VNAV or LPV service is available, then vertical guidance may be used to complete the approach using the displayed level of service.

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9 hours ago, Skates97 said:

I installed dual G5's along with a GNC355 under supervision. It is a great unit. The menus are easy to navigate and the resolution on the screen is very crisp. I would and have recommended it to others.

There is plenty of debate about whether or not you should keep a NAV with ground based capabilities (VOR/ILS) in addition to something like the GNC355 which is GPS only. I'm not going to advocate either way on it, although I opted to keep the Garmin SL-40 and ditch the Narco Mark 12D. That limits me to GPS approaches.

The GNC355 is a TSO-C145c GPS Navigator. Per the installation instructions for IFR flight with the GNC355 you must have "A second GPS navigator, VHF navigation radio, or VHF COM radio with separate circuit breaker(s) and connections(s) to ground from the GNC355."

If you do not have ground based NAV in the panel you can still file GPS at both your primary and alternate destinations with some limitations. They released this back in 2013.

  • 3) Operators of aircraft with TSO-C145() and TSO-C146() navigation systems may utilize GPS-based IAP at both the destination and alternate:
    • a) That are approved to conduct GPS-based IAP under OpSpec/MSpec/LOA C052.
    • b) Must review appropriate Aeronautical Information Services (AIS) and NOTAMs for WAAS service outages. (Reference Advisory Circular (AC) 90-107, Guidance for Localizer Performance with Vertical Guidance and Localizer Performance without Vertical Guidance Approach Operations in the U.S. National Airspace System for more details). In the event of a WAAS failure, WAAS avionics revert to unaugmented GPS functions and operators without baro-VNAV should follow guidance in subparagraph G1) above.
    • c) At the alternate, if not equipped with baro-VNAV may only plan to LNAV (or circling) MDA(h).

https://www.faa.gov/documentlibrary/media/notice/n_8900.218.pdf

It has since been updated in the AIM, page 1-1-34.

https://www.faa.gov/air_traffic/publications/media/aim_basic_w_chg_1_2_3_dtd_12-31-20.pdf

Pilots with WAAS receivers may flight plan to use any instrument approach procedure authorized for use with their WAAS avionics as the planned approach at a required alternate, with the following restrictions. When using WAAS at an alternate airport, flight planning must be based on flying the RNAV (GPS) LNAV or circling minima line, or minima on a GPS approach procedure, or conventional approach procedure with “or GPS” in the title. Code of Federal Regulation (CFR) Part 91 non−precision weather requirements must be used for planning. Upon arrival at an alternate, when the WAAS navigation system indicates that LNAV/ VNAV or LPV service is available, then vertical guidance may be used to complete the approach using the displayed level of service.

This is a whole lot of valuable information, but hard for me to follow as someone that almost has only VFR PPL. I assume the GTN, with NAV built-in avoids this complexity?  I do plan on keeping my KX-155 and KI-209 so it will retain ground based nav and I think ILS capability.  
 

Im really hoping my guys here will let me let me install with oversight.  I redid the whole panel myself...with some help with understanding requirements and some harness work from them installing this would be pretty easy in comparison.  Saves a lot of money as well...

Thanks for your insight. 

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GNC355 with normal spacing - can upgrade later for 8.33 if needed.

Kept the VOR/LOC 155 as my airport still has ILS/LOC and if I need to get down, and the gps has any interruption, I’m still good.

G5 DG/HSI, updated StormScope, and LHS are getting installed right now.

Hopefully TruTrak is a go this year — if not G5 AI will go in...

-Don

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21 hours ago, Skates97 said:

I installed dual G5's along with a GNC355 under supervision. It is a great unit. The menus are easy to navigate and the resolution on the screen is very crisp. I would and have recommended it to others.

There is plenty of debate about whether or not you should keep a NAV with ground based capabilities (VOR/ILS) in addition to something like the GNC355 which is GPS only. I'm not going to advocate either way on it, although I opted to keep the Garmin SL-40 and ditch the Narco Mark 12D. That limits me to GPS approaches.

The GNC355 is a TSO-C145c GPS Navigator. Per the installation instructions for IFR flight with the GNC355 you must have "A second GPS navigator, VHF navigation radio, or VHF COM radio with separate circuit breaker(s) and connections(s) to ground from the GNC355."

If you do not have ground based NAV in the panel you can still file GPS at both your primary and alternate destinations with some limitations. They released this back in 2013.

  • 3) Operators of aircraft with TSO-C145() and TSO-C146() navigation systems may utilize GPS-based IAP at both the destination and alternate:
    • a) That are approved to conduct GPS-based IAP under OpSpec/MSpec/LOA C052.
    • b) Must review appropriate Aeronautical Information Services (AIS) and NOTAMs for WAAS service outages. (Reference Advisory Circular (AC) 90-107, Guidance for Localizer Performance with Vertical Guidance and Localizer Performance without Vertical Guidance Approach Operations in the U.S. National Airspace System for more details). In the event of a WAAS failure, WAAS avionics revert to unaugmented GPS functions and operators without baro-VNAV should follow guidance in subparagraph G1) above.
    • c) At the alternate, if not equipped with baro-VNAV may only plan to LNAV (or circling) MDA(h).

https://www.faa.gov/documentlibrary/media/notice/n_8900.218.pdf

It has since been updated in the AIM, page 1-1-34.

https://www.faa.gov/air_traffic/publications/media/aim_basic_w_chg_1_2_3_dtd_12-31-20.pdf

Pilots with WAAS receivers may flight plan to use any instrument approach procedure authorized for use with their WAAS avionics as the planned approach at a required alternate, with the following restrictions. When using WAAS at an alternate airport, flight planning must be based on flying the RNAV (GPS) LNAV or circling minima line, or minima on a GPS approach procedure, or conventional approach procedure with “or GPS” in the title. Code of Federal Regulation (CFR) Part 91 non−precision weather requirements must be used for planning. Upon arrival at an alternate, when the WAAS navigation system indicates that LNAV/ VNAV or LPV service is available, then vertical guidance may be used to complete the approach using the displayed level of service.

Definitely an option to go GPS only for your approach capability as that will cover 80-90% of your airports when everything is working.  However, I still think it’s a good idea to have ILS capability for flying ifr if you’re in actual weather.  My airport for example has is under a class C near a bigger airport.  It has a GPS into the seldom used runway and an ILS into the frequently used one.  I had to use the ils just yesterday and approach probably wouldn’t have been able to work an opposite direction approach to circle using the GPS.  You may limit yourself to not using my airport and others as a primary or alternate in imc.

Another thought is when things break.  Whether it’s the gps unit or the gps system.  When the gps outage causes my GFC500 to not fly an ILS approach, I’d be ok with that because I can easily hand fly, but if an outage causes me to not be able to land at all because I no longer have any approach capability, that’s a problem.  In my opinion, stuff that helps me cruise IMC  (like an autopilot and gps) is fine but I could always get a vector and hand fly if I really need to.  Approach capability is non negotiable.  I must have a way to get myself down.  If I plan to fly imc, having 2 ways down seems prudent.

Just last month, the military was training near Boise and my G1000/gfc700 work plane was without gps from takeoff up through 22,000’ until we were 100 miles or more away.

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As a Bravo owner who wants to get their plane on the ground ASAP to stop burning fuel, I'll take an ILS over the RNAV.  Too many times you'll have to fly the full "box" vs. being vectored to final approach course like you do on an ILS :) .

 

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2 hours ago, Ragsf15e said:

Btw Skates, I like the 355.  If my 430W failed, I’d probably go with the 355.  I would keep my SL30 though which is connected to an OBS (GI106) separate from my G5s and provides VOR/ILS.

If I had an SL30 in the panel I would have kept it. The Narco 12D had display issues and static issues, the SL40 is rock solid and so is what stayed in the panel.

17 hours ago, Nukemzzz said:

This is a whole lot of valuable information, but hard for me to follow as someone that almost has only VFR PPL. I assume the GTN, with NAV built-in avoids this complexity?  I do plan on keeping my KX-155 and KI-209 so it will retain ground based nav and I think ILS capability.  
 

Im really hoping my guys here will let me let me install with oversight.  I redid the whole panel myself...with some help with understanding requirements and some harness work from them installing this would be pretty easy in comparison.  Saves a lot of money as well...

Thanks for your insight. 

The installation was not complicated, but requires going slow and attention to the details (as anything electronic. The installation manuals and wiring schematics are easy to follow once you are familiar with them. However, in all honesty there were a few times with everything torn apart and wires everywhere that I wondered how much it would cost to have someone put it all back together if I couldn't get it to work....

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On 2/23/2021 at 2:09 PM, Jim Peace said:

They do...there are times though where it would be nicer to have a screen one.

Can you give me context or a scenario where a screen placed D-> is better than the physical soft key?  Thanks!

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