There may well be an additional output to a separate HSI / PFD to give remote advisory guidance without reference visually to the IFD for VNAV and visual approaches which would be the only way the other models of IFD could support this functionality.
E
eal wrote:
the point once you approach the runway for a visual approach to be flying outside the window
Obviously, one fly by looking out of the window but having a standard SOP for GPS cross-check helps, I think there are few optical illusions at play when judging distance or orientation in low visibility (say 3km) going to unfamiliar places (runway size, slope, width, trees, terrain) on final, something to follow a prescribed visual circuit (mostly for noise) would be neat IMO
At home-base, I use GTN to fly under IFR if it’s VMC in aerodrome zone (there are no published GPS IAP and they had a decommissioned VOR IAP that was used by some commercial operators in the past but it does not take you to threshold, it bring you to a nearby forest where the antenna sits, only for the braves 
)
eal wrote:
I am obviously missing a trick here, but I am struggling to see the practical value of managing visual approaches via a GPS navigator. Other than providing location and runway orientation isn’t the point once you approach the runway for a visual approach to be flying outside the window, or is this an attempt to automate this aspect of flying by coupling it to an autopilot?
Even when flying a visual approach you must at some point reach the final approach. The visual approach feature helps you fly a stabilised final approach with a standard glidepath. Sure, you can do that with a PAPI as well (if the runway has one).
I’ve spent some time playing with the IFD simulator and I can’t get it to sequence a visual approach properly other than for a straight in. If you do direct to an airport an then activate the visual approach with, say a left base, it will highlight a long final as the magenta line with the base leg a dashed white line and a ‘gap in route’. I haven’t used the IFD much so maybe doing something wrong?
I asked the question on their forum, and the visual approach (incl. Vertical guidance) will be displayed on conventional HSI and EHSI (à la Aspen).
airways wrote:
I asked the question on their forum, and the visual approach (incl. Vertical guidance) will be displayed on conventional HSI and EHSI (à la Aspen).
I just saw that on the Avidyne forum, and also significantly that despite being advisory vertical guidance you will also be able to couple with it. So this feature and VNAV will be usable on all the IFD models not just the IFD550 via the standard HSI.
E
NCYankee written: (moved from ForeFlight v Garmin Pilot)
What are you using to get LNAV/VNAV vertical guidance? Is there an FMS that has Baro-VNAV vertical guidance on your aircraft?
I do not know where Baro-VNAV is coming from to be honest. My knowledge of the panel avionics wiring/ setup is a quite limited.
Given that the KFC225 is being supplied with Baro-Alt (no separate baro input required) I suspect that whatever is supplying the AP (probably a Bendix Electric Altimeter) is also finding its way into the IFD.
A definite bonus. I was only expecting to benefit from LNAV+V.
Cheers – E
Airborne_Again wrote
Even when flying a visual approach you must at some point reach the final approach. The visual approach feature helps you fly a stabilised final approach with a standard glidepath. Sure, you can do that with a PAPI as well (if the runway has one).
I was fortunate to learn flying based at very short narrow airstrips with no landing aids whatsoever, and the sight picture of a correct final approach has so far kept with me ever since, for which I am grateful. For airports/airstrips with no nav aids I can see that perhaps in marginal VFR weather a cockpit aid could be used to help with a stabilised approach, but other than that, with good visibility I am too busy looking out correcting and finessing that sight picture as necessary to spend additional time scanning another instrument.
Each to his own I guess.
Out of interest. When I was first looking to buy my Jetprop, I came across an avionics suite by Chelton installed in one candidate aircraft that if I recall allowed home grown visual approaches to be programmed in from any waypoint, coupled to the autopilot with vertical guidance, and their implementation of windows in the sky. That was 13 years ago. Has it really taken this long for the other manufactures to catch up?
Cheers – E
I know that the GNS430W/530W does not provide +V outside the SBAS service Volume. The IFD will only annunciate L/VNAV when you are operating in an SBAS service volume with adequate HPL and VPL. I think you may just be getting LNAV+V as the annunciation outside of an SBAS service volume on an RNP approach that has LNAV/VNAV and LNAV minimums and if so, this is advisory and only applies only to the LNAV minimums on the same chart. An annunciation of LNAV+V does not authorize flying an approach to the LNAV/VNAV minimums.
There is definitely a difference in the IFD terminal mode annunciator. LNAV only approaches show GPS→LNAV+V as it transitions, whereas LNAV/VNAV show as GPS→LNAV/VNAV. I would have thought if the RNP integrity for supporting VNAV was not met, the IFD would automatically downgrade the approach? Otherwise this would be very misleading.
The difference in minima between the two can be as much as several hundred feet.
E
