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Thread: Should I include NAV capability with COM/NAV Radio replacement

  1. #1

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    Should I include NAV capability with COM/NAV Radio replacement

    I am in the process of planning to update the avionics in my Super Cub and have a question on whether or not I should install a new radio with NAV capability, along with the associated CDI and NAV antenna, or simply stick to a new COM radio.

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    Quote Originally Posted by mjdonovan View Post
    I am in the process of planning to update the avionics in my Super Cub and have a question on whether or not I should install a new radio with NAV capability, along with the associated CDI and NAV antenna, or simply stick to a new COM radio.
    The problem is, panel mount NAV capability is not as capable as the portable stuff, except in a few situations:

    1. You are going to someday put in an autopilot and want it to track a course.
    2. You don't want to mess with carrying a portable or risk it getting *easily* stolen
    3. You are going to set it up for IFR (even if not certified as such)
    4. Money grows on trees at your house

    I took the GNS420 out of my cub and swapped it with the GNS250XL in the 180 (both old school radios) because I did not need IFR nav in the cub. I like having the built in GPS in it, but I could live without it.

    sj
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  3. #3
    slowmover's Avatar
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    I have two nav radios in my Cessna. I fly IFR but almost never use the nav radios. It’s all GPS. I suppose I keep them in case the GPS ever quit and I still wanted IFR capability.

    But in a Super Cub that I never intended to fly IFR? No way would I install them. Spend the money on something else.

  4. #4

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    Quote Originally Posted by mjdonovan View Post
    I am in the process of planning to update the avionics in my Super Cub and have a question on whether or not I should install a new radio with NAV capability, along with the associated CDI and NAV antenna, or simply stick to a new COM radio.
    Specifically I was looking to install a GNC-255A (for COM and VOR/Localizer nav). Not a GPS system.

  5. #5
    SJ's Avatar
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    Then I would say a resounding "NO" unless you want to shoot an ILS/LOC. GPS approaches overlay nearly all VOR approaches these days.

    sj
    "Often Mistaken, but Never in Doubt"
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  6. #6
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    Quote Originally Posted by mjdonovan View Post
    Specifically I was looking to install a GNC-255A (for COM and VOR/Localizer nav). Not a GPS system.
    It’s fine to put one in if you’d feel like you were missing something without one. In your recent flying have you tracked VORs or localizers much, or have you wanted the ability to do it? If yes, then go for it. It’s better to be comfortable with you avionics than to feel like they’re holding you back, even if you don’t use some of the capabilities often.

    If you fly day VFR and aren’t the type to fly in iffy weather you probably don’t need it. I never felt the need for a NAV radio in my PA-12; the GPS was just fine for day VFR.

    If the GNC-255A has a built in CDI display you should consider leaving out the analog CDI. At work, if I want to hand fly a localizer approach I prefer to use the CDI feature built into the Garmin NAV/COM/GPS over the analog CDI or HSI. I seem to be able to detect course deviations more quickly, and the left/right arrow with distance feature is really helpful in fine tuning my wind correction factor.

    If you’re considering the NAV capability as a backup in case of failure of your GPS or to save your bacon in the event of an inadvertent IMC encounter it might serve that purpose, but it’s hard to track a localizer if you don’t practice it regularly.
    Speedo

  7. #7
    wireweinie's Avatar
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    What type of flying do you actually do? Do you use nav now? For normal VFR flying, I wouldn't waste the weight and space unless you ave a specific need. Just like any other equipment, don't install it if you MIGHT need it, install it if you DO need it.

    Think about it. You'll have a about three to four pounds of nav/com radio. More if you need an indicator. If you stay with a Becker com and a portable GPS you could get down to close to two pounds. The square nav/com will take up a spot 6 1/4" w X 3" h X approx 14" d. And a Cub panel is not designed to hold square radio trays, so you have to make hanger brackets for it. The Becker com fits in a 2 1/4" instrument hole with no tray (approx 8" deep) and your portable GPS doesn't even need to be mounted in a panel cutout.

    Your wallet and your call.

    Web
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    There is no GPS system in the plane. I only have a handheld Garmin Aera 500 GPS unit. So, I was thinking having a NAV feature in the only panel-mounted radio in the plane gave me the ability to fly VOR routes in the event I lost my GPS unit (e.g. loss of battery). Also, having the LOC capability also offered some protection if WX dropped unexpectedly at an airport of intended landing.

  9. #9
    wireweinie's Avatar
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    First off, if you have a portable GPS in the aircraft it should have a hardwired power source with spare batteries as a backup. I have some customers that fly with a couple of portables, just in case.

    What will the nav do for you that your GPS won't? If you get stuck in some soup right now, your 500 has the capabilities to get you out. It has more info on it than watching a VOR needle.

    I'm assuming that you're not intending to go certified IFR, correct?

    Web
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  10. #10

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    That's another item I am putting in the plane, a hardwired power source. I'm thinking a USB port with clock for powering the Aera 500 Unit.

    Correct, the aircraft won't be IFR cert.

  11. #11
    wireweinie's Avatar
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    Use the Garmin 'bare wire' (010-11385-03) cable assembly. It has a fused lead or you can cut the fuse off (I always do) and connect it to a circuit breaker. Use the USB charge port for something else.

    Web
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  12. #12
    hotrod180's Avatar
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    Or have a GPS app n your smartphone as backup.
    I have a buss-powered tablet running the avare app on the panel,
    and a smartphone with Avare in my pocket.
    I also had my old Garmin 196 on the panel, but found I never used it so out it came.
    Gave it to a buddy who'd never (!!_) owned or used a GPS, so he can see what it's all about--
    I suggested he get a smartphone with a GPS app, but he's reluctant to give up his flip phone.
    Cessna Skywagon-- accept no substitute!

  13. #13
    wireweinie's Avatar
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    Quote Originally Posted by wireweinie View Post
    Use the Garmin 'bare wire' (010-11385-03) cable assembly. It has a fused lead or you can cut the fuse off (I always do) and connect it to a circuit breaker. Use the USB charge port for something else.

    Web
    This cable also has the RS 232 data lines in it. Handy for connecting GPS data to other units.

    Web
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  14. #14

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    I had a COM/GPS Nav. radio in my cub when I purchased it but typically used the portable for navigation because it was way easier (plus the display wasn't between my knees). Was nice to be able to check distances to other places while flying but overall I don't miss it and the Trig radio is way better and lighter. Lots of folks around here have navigated virtually the entire country with just a Garmin portable.

    Come on over to the dark side and pretty soon you'll be asking what's a VOR
    Remember, These are the Good old Days!

  15. #15

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    The Garmin nav coms seem to all be GPS-based. Putting a VOR in is just creating a waypoint, then using the CDI presentation. I can make one of those things sit up and talk, but only if I study the manual the night before, and take notes - especially when using the OBS feature. Yuk!

    If you want VOR nav, consider a KN-53. It really does receive raw VOR signals. I use mine as a backup when I shoot practice ILS approaches with the Garmin 496 or 295. And I have a horizontal flight director on the hand-held. What marvelous gadgets!

  16. #16
    wireweinie's Avatar
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    Quote Originally Posted by bob turner View Post
    The Garmin nav coms seem to all be GPS-based. Putting a VOR in is just creating a waypoint, then using the CDI presentation.
    Can you explain that? What models are you referring to?

    Web
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  17. #17
    Iflylower's Avatar
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    Quote Originally Posted by wireweinie View Post
    Can you explain that? What models are you referring to?

    Web
    Web, without putting words in Bob’s mouth, I understand his statements as...... you make a flight plan on these units waypoint to waypoint to vor to waypoint. You may be naving to or from a vor, but you’re doing it with gps guidance, same as you would be with a Garmin 496 or Aera. Same with the obs feature, which makes a gps point act like a vor course. You must deselect gps to get into actually using vor signals. Anyway, you know this stuff.

    i personally think VOR is dead and has little future. Get the new aera that uses our gps and backs up the Russian gps system. Have a phone or tablet back up to your portable. Don’t put in special antennae’s and receivers to run vor. To much weight and install cost. VOR’s are rarely in your direct line anyway. Opinion.

  18. #18

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    I believe the 430 series do have VOR receivers in them, but the lower numbers - 300, etc - do not have a way to tune a VOR frequency. VORs are in their databases, and ther is a way to simulate an OBS. It is quite complicated - not something you want to be doing single pilot IFR.

  19. #19
    wireweinie's Avatar
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    The GNC 250 and 300 series were just GPS/Com units. But they could be used to drive a CDI. They're still very popular units up here. And they fit nicely in a Beaver panel.

    Web
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  20. #20

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    One word - Terrain. I'm having a used, non-WAAS Garmin 430 with terrain installed in my SC as we speak. Terrain capability lets you see a map of what is beyond the mountains in front of you, all in relation to your own altitude. Why would someone flying in the mountains not want that on the instrument panel??

    Another consideration - IFR currency. If you are IFR certified and want to stay current, you have to log approaches and holdings. Having a Nav-Com allows you to do that without renting a plane every few months.
    Last edited by Tennessee; 01-24-2019 at 06:26 PM.

  21. #21

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    Nobody has mentioned one big use for this would be for Awos weather at uncontrolled airports but than you would need an audio panel I believe

  22. #22
    wireweinie's Avatar
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    Why wouldn't you just listen to AWOS on the com?

    Web
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  23. #23
    mvivion's Avatar
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    People, I’m one who flew before there was GPS, and in a lot of country where VOR wasn’t available. And LORAN totally sucked (too far north, and baseline extension, etc).

    I cant imagine why anyone in their right mind would even vaguely consider a VOR receiver, UNLESS they are flying IFR, and that’s nit what Cubs are for.

    MTV

  24. #24
    hotrod180's Avatar
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    Quote Originally Posted by Mnjoe View Post
    Nobody has mentioned one big use for this would be for Awos weather at uncontrolled airports but than you would need an audio panel I believe
    ?? The AWOS freq's I'm familiar with are in the com frequency spectrum (118.00 - 136.97).
    Cessna Skywagon-- accept no substitute!

  25. #25
    wireweinie's Avatar
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    Quote Originally Posted by mvivion View Post
    People, I’m one who flew before there was GPS, and in a lot of country where VOR wasn’t available. And LORAN totally sucked (too far north, and baseline extension, etc).

    I cant imagine why anyone in their right mind would even vaguely consider a VOR receiver, UNLESS they are flying IFR, and that’s nit what Cubs are for.

    MTV
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  26. #26

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    Quote Originally Posted by mvivion View Post
    People, I’m one who flew before there was GPS, and in a lot of country where VOR wasn’t available. And LORAN totally sucked (too far north, and baseline extension, etc).

    I cant imagine why anyone in their right mind would even vaguely consider a VOR receiver, UNLESS they are flying IFR, and that’s nit what Cubs are for.

    MTV
    As far as combined Navcom units go, most of the units like the GNS430 and later will have VOR and localizer capability built in anyway. Add in the terrain and IFR currency issues I mentioned above and it all seems to make sense to me. I'm having the my transponder replaced with a newer used removed from another plane, adding a turn coordinator, adding a CDI, getting the old King 155 radio replaced with the GNS430 and adding ADS-B out, all for a net weight increase of only about 3 pounds. I'll probably never once file IFR from the ground with my Piper, but if I ever get caught on top of a cloud layer I'll have a legitimate and safer path back down with a pop-up clearance. One thing I'm sure I will use is the flight plan aspect of the 430. Another big issue for those of us who live in more populated areas is airspace avoidance. Knoxville has a class C at TYS and I fly the Piper out of DKX, which is on the edge of it. The Garmin warns if a pilot is about to entered B, C or D.

  27. #27

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    The Garmin GNC 420 and GNC 420W are the same as the GNC 430 only without VOR/LOC capability. If you want to intercept a given radial, simply execute "DIR To" a given VOR and select a course to or course from, just like the big boys with their FMC's. It is fully IFR capable and you have the added benefit of having a frequency data base so you can easily look up frequencies even FSS, CTAF and AWOS. If you highlight the frequency and press "ENTER" it will put it on the ready pad for selection. If you know how to fully use the features of the Garmin 400 series units you can stow your chart except for emergency use. You also can put check lists on it and it has a nice timer function. It is a real "Swiss Army Knife" in the cockpit if you know how to use all if its features. A while back I lost my nav display while in IFR and shot an RNAV using only the Garmin GNC 420W's internal CDI. VFR or IFR I consider it the bomb.

    If you want IFR capability the reality is most airports with a VOR approach have an RNAV approach and if it has an ILS it usually has an RNAV to LPV minimums which rarely differ more than 50' on minimums. So a WAAS enabled GPS with a vertical deviation indicator will get you just about everything you need for IFR.
    Last edited by GeeBee; 01-27-2019 at 10:04 AM.

  28. #28
    mvivion's Avatar
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    Quote Originally Posted by GeeBee View Post
    The Garmin GNC 420 and GNC 420W are the same as the GNC 430 only without VOR/LOC capability. If you want to intercept a given radial, simply execute "DIR To" a given VOR and select a course to or course from, just like the big boys with their FMC's. It is fully IFR capable and you have the added benefit of having a frequency data base so you can easily look up frequencies even FSS, CTAF and AWOS. If you highlight the frequency and press "ENTER" it will put it on the ready pad for selection. If you know how to fully use the features of the Garmin 400 series units you can stow your chart except for emergency use. You also can put check lists on it and it has a nice timer function. It is a real "Swiss Army Knife" in the cockpit if you know how to use all if its features. A while back I lost my nav display while in IFR and shot an RNAV using only the Garmin GNC 420W's internal CDI. VFR or IFR I consider it the bomb.

    If you want IFR capability the reality is most airports with a VOR approach have an RNAV approach and if it has an ILS it usually has an RNAV to LPV minimums which rarely differ more than 50' on minimums. So a WAAS enabled GPS with a vertical deviation indicator will get you just about everything you need for IFR.
    Exactly. And with one of those units, you’ll actually be USING the nav function pretty much every time you fly. And still have that “get out of jail” card for an instrument let down.

    MTV

  29. #29
    Bluebear's Avatar
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    Quote Originally Posted by wireweinie View Post
    Can you explain that? What models are you referring to?

    Web




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  30. #30

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    GeeBee's points about the GNC 420 are well taken. Part of my goal with my upgrade was not to turn my Piper into a Cirrus, but I did want upgrades that would add to safety. I went with a non-WAAS GNS 430 instead of a WAAS model. I've been flying with 430's since I got my PPL, so that's part of why I wanted a 430. If I ever needed the WAAS LPV minimums I would have really screwed up on my preflight weather planning. I had the avionics shop wire the tray for a possible slide in WAAS upgrade in the future though. The 430 is more expensive than the GNC 420 units by about 2K or so, but because tens of thousands of pilots are familiar with the 430's and there is going to be a resale issue eventually (I ain't getting younger!), I thought it would be a better investment. There's no such thing as a good investment with avionics, though.

    A Garmin Aera unit like mjdonovan mentioned is a great idea. I also did that, but I went with a used Aera 560 unit. It adds reliable (non-government) XM weather and another terrain source to what the 430 has. Plus flight planning, current AWOS's and a lot of other good things, too numerous to mention. Ram has good 17 mm ball mounts for it.

  31. #31
    mvivion's Avatar
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    Function of the Garmin 420 is identical to the 430. Just doesn’t have VOR. Another issue with VOR is that to be legal, it has to have a seperate indicator. Another 3 1/8 gauge in a tight panel.

    MTV
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  32. #32
    wireweinie's Avatar
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    My own feeling is that putting a VOR or IFR GPS into a Cub is like putting an expensive, long range scope on a short range beater rifle. Why do it?

    If you want to get home under unforeseen circumstances get a quality portable. If you feel that it needs back up, get a second unit. If you want to train for IFR, the Cub is just a bad choice for a platform.

    On the other hand. If you just have the overwhelming need to spend your money and use panel space, get the most for your buy. The 400 and 420 units take up the same weight/space footprint as a GNS 430/430W. So if you are giving up panel space and weight, get the unit that gives the most back, with the com/VOR/GPS systems. And if you're willing to give that up, installing a nav head won't be much worse. By the way, Mid Continent has a 2 1/4" CDI.

    Your wallet.

    Web
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  33. #33

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    Well you could go with an Aspen unit or a Garmin G5 and kill two birds with one stone on the CDI unit. My only thing is I don't want an ugly old VOR antenna sticking out of my airplane so I am with the 420. Yes they operate identically. The advantage with the 430 is you have more flexibility in filing alternates but I find most let downs in planes like a Cub are ad hoc affairs so you usually in up with a pop up clearance.

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