G500 in Europe? And with KFC225?

Generally, for 100% airspace awareness and clarity, the panel-mount GPS boxes and MFDs are rather worthless. While on theory the y do show all airspace, they often show bogus airspace, lack clarity and depth of information. Anybody who flies at least some VFR with such equipment also has an iPad running, usually with Skydemon.

boscomantico wrote:

Generally, for 100% airspace awareness and clarity, the panel-mount GPS boxes and MFDs are rather worthless. While on theory the y do show all airspace, they often show bogus airspace, lack clarity and depth of information. Anybody who flies at least some VFR with such equipment also has an iPad running, usually with Skydemon.

+1

If you also keep in mind that some of the CAS/DA/RA/PAs are variable and activate by a NOTAM (sometimes just in the morning!), then it really makes it worthless…
What works in G500? The usual integration with DME+ADF. Weather? If you have a radar or a rare thing called GSR-56 for satellite uplink. XM and UAT weather is out, obviously. ADL weather could probably be connected to G500 somehow? @Sebastian_G might be able to confirm.
re: A/P – VNAV+LPV+ILS VNAV should work, as for enroute VNAV I’m not sure, as I’ve read somewhere that ALL VNAV on GTN devices works only with Garmin GFC autopilots. But what does not work? I don’t know.

Panel GPS does not allow you to distinguish DA, RA, PA and does not allow you to see any TDA, TRA, TPA from NOTAMS…I fly low VFR (and OCAS IFR), I would not rely on Panel GPS for airspace serious matters, how do you fly around TFR using G500? say when not talking to ATC

I think SkyDemon does this very well and it’s well back-tested by users and they are reactive to correct issues (there was a bug in July 14th NOTAM airspace vs AIP-SUP on mentioning it they fix it in 1h)

In the US, things are way easier and pannel GPS is likely enough, one will check runway NOTAMS and stay away from Bravo, for the rest if you file VFR and talk to ATC, they will sort it out, including that clearance to cross TFR with POTUS golfing under, ‘no worries Sir, you got the squawk’

What do/don’t you get with the G500/KFC225 combination (if anyone else has used this combination)? Do you get GPSS? VNAV? Or does the KFC225 just work completely standalone?

The KFC225 has the usual “classic” facilities i.e. HDG mode (which should work off a heading bug on your HSI/EHSI), NAV mode (which tracks an analog H input, on which the HSI course pointer provides the initial “heading”) and it can track a V signal for ILS GS.

There is some “buttonology” for flying LPV with it. @NCyankee wrote about this in the past. You need to make sure this has been correctly wired.

I believe there is a way to connect a Sandel SN3500 EHSI to a KFC225 so that the KFC flies ILS or LPV and is not aware of the signal source (it predates LPV) in the button sequence, and this not only works but is legal. I haven’t got around to wiring mine up yet in that way but would do once I get an IFD540/550. The G500, I have no idea.

A KFC225 also has roll steering via ARINC429 and this works in NAV mode from the usual IFR SBAS (WAAS/EGNOS; 5Hz GPS rather than the pre-SBAS 1Hz GPS) navigators. I don’t use that on mine because I have a KLN94 which is 1Hz. The HSI in the G500 and the output of the GTNs should work with this but I don’t know anything about it; @wigglyamp may know more on the wiring side if he is still out there.

The KFC225 is a very accurate autopilot; fully “digital”. Not without issues – summary – but those are aircraft type dependent.

You must check the avionics operation carefully because so much stuff is wrongly wired and since so few pilots are willing/able to understand it, a plane can be flying for years without anybody noticing. I know a guy who installed 100+ GNS boxes without ever connecting up the HSI course pointer to anything, and nobody noticed!

A tablet will deliver a better VFR map presentation but can’t control an autopilot etc so the panel mount systems need to work; everything else is a “toy” which can be a “useful toy” if you use it correctly.

johnh wrote:

What do/don’t you get with the G500/KFC225 combination (if anyone else has used this combination)? Do you get GPSS? VNAV? Or does the KFC225 just work completely standalone?

The KFC225 in combination with a GNS/GTN/IFD WAAS GPS supports a NAV mode that operates differently based on the source, either GPS or VOR/LOC. When VOR or LOC is the Nav source, the autopilot uses the CRS pointer as the selected course and uses the HSI left/right analog signals to guide the autopilot laterally. When GPS is the Nav source, the lateral course is based on the GPS roll steering output, if present. Roll steering is sometimes referred to as GPSS. When GPS is the Nav Source and roll steering is not available, the lateral guidance uses the same method as is used with VOR/LOC. So Nav mode is selected with a GPS source and roll steering, is effectively automatic GPSS. APR mode only supports VOR/LOC type guidance, that is the lateral is based on the CRS pointer as the reference, and the left/right analog signals from the HSI. In APR mode, if there is a localizer detected (I:S energize signal) and a GS, then the vertical path will transition at GS intercept to tracking the GS. There isn’t a lateral mode using roll steering when in APR mode, so once APR mode is selected, the only lateral guidance is based on the CRS/left/right inputs.

The G500 adds the ability to switch the Nav Source between two Nav systems, so if you have a GTN #1 and a GTN #2, you can use the CDI button to select either GPS 1, GPS 2, VOR/LOC 1, or VOR/LOC 2. The G500 also has a GPSS function built in that may be used when selecting either GPS 1 or 2 as the Nav Source, but it requires the KFC225 to have HDG selected and GPSS selected on the G500. Most legacy autopilots do not have built in support for GPSS, so convertors have been designed to convert the roll steering output to a heading error signal and interface to the legacy autopilot through the heading mode. Heading mode is designed to command the autopilot bank angle to correct the heading to match the heading bug on the HSI by commanding a bank towards the selected heading where the bank angle is proportional to the difference. This is called the heading error signal, so for example a heading difference of 5 degrees might command a bank of 5 degrees towards the bug, a heading difference of 10 degrees might command a bank of 10 degrees, and so on up to the maximum bank angle supported by the autopilot. The roll steering output from the GPS is also a bank angle, so the conversion from a roll steering bank angle to a heading error bank angle signal is straight forward. If I had a KFC225, I would use the built in support for roll steering and disable it in the G500, because the former works in Nav mode, while the latter works in HDG mode.

Since the KFC225 does not have any built in support for vertical guidance when the Nav source is GPS, LPV or LNAV/VNAV or LNAV+V is not natively supported. To get the autopilot to fly a vertical GPS approach path, the signals for an ILS must be faked. There is a big issue with this in that when flying a vertically guided GPS approach, requires that the initial part be flown using GPS as the source, and a faked LOC/GS as the source in order to intercept and track the GP. The KFC 225 has a characteristic that if the autopilot detects a Nav Source change, it kicks out of a Nav or Apr mode and reverts to a wings leveler Roll mode. This was deemed unacceptable by the FAA, so Garmin added a Prompt function to obtain certification. So without the Prompt mode, if the pilot flew an LPV using GPS source Nav mode and once at the IAF the pilot selected APR, the fake LOC/GS signals would come on later in the procedure and the autopilot would detect the Nav mode source change, and kick out to roll mode. With prompt mode, the pilot selects the GPS and uses Nav mode, but does not select the APR mode on the autopilot until prompted to do so. The prompt occurs as soon as the FAF becomes the active fix. The pilot then selects APR on the KFC225, but since this is after the Nav Source mode change to assert the fake LOC/GS signals, the autopilot stays engaged for the remainder of the LPV seeing LOC/GS type signals.

The GTN supports vertical navigation which adds altitudes to each flight plan waypoint. Vertical enroute/terminal navigation (called VNV) only supports descents and provides a hollow vertical guidance indication on the G500 to guide the pilot to make descents on a STAR or an approach up to the FAF. This is a form of Baro/VNAV where the vertical guidance (VNV) is based on the altimeter input and the GPS along path position. It requires a digital autopilot to follow the vertical VNV guidance. The Garmin GFC 500 or 600 supports this. Legacy autopilots, including the KFC 225 do not. My understanding is that the Stec 3100 system will also support following the vertical Nav VNV. I have an Stec 60-2 autopilot and on each approach, I turn off VNV in my GTN750Xi because I make the descent from the IF to FAF leg using APR mode rather than VNV, which my autopilot does not support.

NCYankee wrote:

The G500 also has a GPSS function built in that may be used when selecting either GPS 1 or 2 as the Nav Source, but it requires the KFC225 to have HDG selected and GPSS selected on the G500

This isn’t actually the case. The G500 can output the GPSS signal in ARINC 429 directly to the autopilot, so the KFC225 can still use Nav mode. From the G500 STC install manual:

2.5.16.1 ARINC 429 GPSS
The G500/G600 (GDU 620) has an ARINC 429 output that can be connected to autopilots that are capable
of utilizing ARINC 429 GPSS information. On the AUTOPILOT ARINC 429 output, the GDU 620
forwards GPSS information from the navigator (1 or 2) that is currently selected on the GDU 620 HSI –
there is no need to provide external switching. For installations with autopilots that accept 429 GPSS (e.g.,
S-TEC 55X and Honeywell (Bendix-King) KFC 225) an external GPSS switch is NOT required.

Here’s the KFC225 interconnect to the G500:

What does that wiring diagram actually tell us about the capability, and the procedure for flying LPV with it?

wigglyamp wrote:

This isn’t actually the case. The G500 can output the GPSS signal in ARINC 429 directly to the autopilot, so the KFC225 can still use Nav mode. From the G500 STC install manual:

When the ARINC 429 signal is connected to the KFC 225, there is no need for a GPSS selection from within the G500 as it is part of Nav Mode.