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NAV/COM Choices

GrinchF16

Well Known Member
Looking at replacing my iCom radio with a NAV/COM. SL30 used is $3000+ or the new Trig TX-56A has just been released at around $4000. I know Trig has been around a while and reviews seem positive but have personally never used. Biggest question would be compatibility with my Dynon panel. Anyone have SA or pertinent thought?
 
While the SL-30 is still the best NAV/Comm, Garmin letting support for it die away removes it as an option for me.

For the new project I plan on a Garmin GNC-355 and this new Trig Nav/Comm (I consider the GNC-355 a better option over the clunky GTN-650 I put in the last two RVs). As Trig also provides the SkyView XPDR and Dynon Comm I was hoping (and still hope) that Dynon will use this new Trig NAV/Comm as on option over the fully integrated Trig Dynon radio - including a NAV/Comm remote panel control module.

Perhaps you guys at Oshkosh can squeeze them on this….

Carl
 
While the SL-30 is still the best NAV/Comm, Garmin letting support for it die away removes it as an option for me.

For the new project I plan on a Garmin GNC-355 and this new Trig Nav/Comm (I consider the GNC-355 a better option over the clunky GTN-650 I put in the last two RVs). As Trig also provides the SkyView XPDR and Dynon Comm I was hoping (and still hope) that Dynon will use this new Trig NAV/Comm as on option over the fully integrated Trig Dynon radio - including a NAV/Comm remote panel control module.

Perhaps you guys at Oshkosh can squeeze them on this….

Carl

The alternative to the SL-30 is the GNC -255 which is more expensive and well supported and works well with the HDX. I wanted ILS/VOR capability and LPV capability but had reservations about having to have a subscription to FlyQ for the HDX ( no options for maps and plates on HDX) and a subscription to Foreflight for Garmin GNC-355/GPS-175 plates and approach updates (Garmin does not support FlyQ according to Garmin tech support).
I made provisions on my panel to install a GPS-175 or other standard panel mounted navigator if/ when the situation changes. When considering options for displays, radios, navigation and autopilot components the hidden incompatibilities and limitations need to be fully explored before committing to a particular configuration.

KT
 
Don't rule out the new Trig TX56A and TX57A. While these have been newly introduced I suspect they will be excellent radios, much like a current-manufacture SL-30.
 
Don't rule out the new Trig TX56A and TX57A. While these have been newly introduced I suspect they will be excellent radios, much like a current-manufacture SL-30.

But, can they feed my EFIS ILS data and a VOR cross-fix bearing, simultaneously, like my SL30?
 
But, can they feed my EFIS ILS data and a VOR cross-fix bearing, simultaneously, like my SL30?

From the installation manual:
5.6.11 RS232 Input/Output
The RS232 input allows certain third-party multi-function displays to preload the standby and active frequencies and to monitor the Nav/Com status. The radio understands the Apollo SL30 protocol ($PMRRC and $PMRRV) and the Garmin GNC protocol ($PGRMC and $PGRMV), both of which are based on NMEA at a speed of 9600 bps.

So the answer is “possibly”. The manual mentions the standby channel providing the cross fix reference but at a lower update rate (which is not specified) so it may emulate the SL 30. There is no mention of ARINC 429 or CAN bus interface capability so full SL 30 and GNC compatability may not be possible.

KT
 
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… but had reservations about having to have a subscription to FlyQ for the HDX ( no options for maps and plates on HDX) …

KT
You can purchase charts and plates from Seattle Avionics for $119 a year that display on the HDX. You do not need FlyQ. You download the data onto a thumb drive and insert it into one of the USB ports on the HDX (usually via an extension to make access easier). The data stays on the thumb drive and it stays in the USB port. You need a thumb drive for each screen but only one subscription from Seattle Avionics.
 
Yep SA does both FlyQ and the Dynon charts - I have both a lifetime subscription to FlyQ for a Ipad Mini and the annual subscription for the HDX since the FlyQ package can’t be loaded on the HDX. I was baulking at having to buy a third (Foreflight) package for Garmin products since Forflight can’t be loaded on the HDX.

KT
 
The Trig web site specifically says it can output the radial from the standby VOR, just like the SL30.

Trig told me (prior to product release) that their nav/comm would be a form/function replacement for the SL30 but not a fit replacement (i.e. not a slide-in replacement). I would very much like to get my hands on one of these to test. My SL30 is rock solid and I still believe it is likely the best nav/comm ever made but the Trig may take that position as Garmin lets the SL30 fade into the sunset.
 
The spec for the TX56/57 shows only RS 232 bus interface- no ARINC 429 or CAN bus so interfacing to a HDX may be a problem depending on the other interfaces competing for the five available RS232 ports. Interfacing to a G3/G5 system may also be a problem. Having the capability to display and use the standby nav channel bearing for VOR signals (only) is a big plus but in the greater scheme of things if you are totally committed to land based approach guidance then one nav receiver will provide a 10E-4 failure rate even if it can display the standby channel, which doesn’t cut it - you need two nav receivers to meet a 10E-6 or better number. Having a single GPS based approach capable receiver and a single VOR/ILS receiver is the basis for an interesting discussion on meeting IFR equipment availability numbers and alternate procedures in the event of an equipment failure situation. Based on the demonstrated performance of other products from the Trig stable the TX56/57 range are likely to be product leaders but it will have serious competition from the GNC 255 which does have ARINC429 and CAN bus interfaces in addition to RS232 despite not being able to display the standby nav channel data.

KT
 
Which is in keeping with their ‘just like the SL30’ design philosophy.

Exactly - an excellent design that was “state of the art” “cutting edge” when it was designed 30 years ago by Apollo when steam gages were the norm and early glass GA displays were coming available for EAB and the need for multiple databus options was less obvious. The point I was making (it seems I need to spell it out) is that having ARINC429 and CAN bus interfaces more than offsets the lack of capability to display the standby channel data given that a single NAV RX cannot make the availability numbers if you are serious about IFR flight.

KT
 
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The spec for the TX56/57 shows only RS 232 bus interface- no ARINC 429 or CAN bus so interfacing to a HDX may be a problem depending on the other interfaces competing for the five available RS232 ports. Interfacing to a G3/G5 system may also be a problem. Having the capability to display and use the standby nav channel bearing for VOR signals (only) is a big plus but in the greater scheme of things if you are totally committed to land based approach guidance then one nav receiver will provide a 10E-4 failure rate even if it can display the standby channel, which doesn’t cut it - you need two nav receivers to meet a 10E-6 or better number. Having a single GPS based approach capable receiver and a single VOR/ILS receiver is the basis for an interesting discussion on meeting IFR equipment availability numbers and alternate procedures in the event of an equipment failure situation. Based on the demonstrated performance of other products from the Trig stable the TX56/57 range are likely to be product leaders but it will have serious competition from the GNC 255 which does have ARINC429 and CAN bus interfaces in addition to RS232 despite not being able to display the standby nav channel data.

KT

In this response I believe one of the most basic principles of navigation is perhaps overlooked. One doesn't have a radio which monitors two nav fixes for the purpose of redundancy. One uses the two nav fixes to establish one's position. The crossing of pointers from two different VOR radials provides a pretty solid position fix.

If one wants to improve "reliability" or "availability" or "probability of mission completion" one adds another radio. If one wants to know where they are while bumping around up in the clouds, one wants to add navigation fixes by referencing as many navaids as possible! :D
 
.... given that a single NAV RX cannot make the availability numbers if you are serious about IFR flight.

KT

Not sure what you meant by this statement. In an era when many are flying IFR with only a GPS receiver (which I personally do not do, having once experienced a complete loss of GPS signal on approach) I feel a single SL30 is an acceptable backup. With the availability of the standby VOR displaying a cross fix (either as a to/from bearing on the S30, or as an RMI needle on my GRT EFIS HSI display) I have all I need to shoot the ILS at nearby SCK, even in a complete GPS blackout.
 
In this response I believe one of the most basic principles of navigation is perhaps overlooked. One doesn't have a radio which monitors two nav fixes for the purpose of redundancy. One uses the two nav fixes to establish one's position. The crossing of pointers from two different VOR radials provides a pretty solid position fix.

If one wants to improve "reliability" or "availability" or "probability of mission completion" one adds another radio. If one wants to know where they are while bumping around up in the clouds, one wants to add navigation fixes by referencing as many navaids as possible! :D

I completely agree with your first point. Old School VOR and ILS IFR navigation requires two independent VOR/ILS receivers to ensure availability since the demonstrated failure rate and consequences of loss of the VOR/ILS RX if only one is available is unacceptable. This shouldn't be a point of contention or further discussion. The need for two independent COM radios follows the same argument. The configuration of a single VOR/ILS and a single LPV capable GPS navigator is very worthy of discussion from a airplane configuration and system failure rate and safe plan B after the first failure either due to GPS blackout or aircraft equipment failure.

On your second point - being IFR and totally dependent on either a single GPS RX or VOR/ILS isn't an option in my view and having the capability to observe the radial from the standby Nav may have some utility there is still the need for alternate independent methods of navigating and shooting an approach (LPV GPS or a second SL30/GNC255/TX56)

In an Old School system with two VOR/ILS RX and no GPS having the standby channel radial displayed is very valuable since it allows the full VOR approach capability - not so important in a mixed VOR/ILS and LPV GPS system.

KT
 
Not sure what you meant by this statement. In an era when many are flying IFR with only a GPS receiver (which I personally do not do, having once experienced a complete loss of GPS signal on approach) I feel a single SL30 is an acceptable backup. With the availability of the standby VOR displaying a cross fix (either as a to/from bearing on the S30, or as an RMI needle on my GRT EFIS HSI display) I have all I need to shoot the ILS at nearby SCK, even in a complete GPS blackout.

The point I was trying to make is that one of either LPV GPS or VOR/ILS as the sole navigation and approach equipment is unacceptable from a failure rate and consequences point of view. Having a SL30/TX56/GNC255 as a backup is worthy of discussion. If the LPV GPS fails (for any one of a number of reasons) then the SL30 and TX56 have the displayed standby channel and if the failure is due to a complete GPS blackout then I would agree with you.
For the GNC 255 the option is switching the standby to active and back again during approach capture but shouldn't be necessary once established. If the failure is in the LPV GPS equipment and GPS map is available then navigating to the FAF shouldn't be an issue. Good subject for a discussion.

KT
 
Not sure what you meant by this statement. In an era when many are flying IFR with only a GPS receiver (which I personally do not do, having once experienced a complete loss of GPS signal on approach) I feel a single SL30 is an acceptable backup. With the availability of the standby VOR displaying a cross fix (either as a to/from bearing on the S30, or as an RMI needle on my GRT EFIS HSI display) I have all I need to shoot the ILS at nearby SCK, even in a complete GPS blackout.

The point I was trying to make is that one of either LPV GPS or VOR/ILS as the sole navigation and approach equipment is unacceptable from a failure rate and consequences point of view. Having a SL30/TX56/GNC255 as a backup is worthy of discussion. If the LPV GPS fails (for any one of a number of reasons) then the SL30 and TX56 have the displayed standby channel and if the failure is due to a complete GPS blackout then I would agree with you.
For the GNC 255 the option is switching the standby to active and back again during approach capture but shouldn't be necessary once established. If the failure is in the LPV GPS equipment and GPS map is available then navigating to the FAF shouldn't be an issue. Good subject for a discussion.

KT
 
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