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I did some pondering and figure the only practical benefit to a GNS unit getting fed baro altitude and heading would be to improve turn anticipation. I've found this to be a bit of a weakness when starting an approach with a tailwind before the turn.

By some magic I don't quite get, even now when on a given flight I first go to the GNS page to calculate TAS/DA, the altitude always agrees with my currrent baro altitude within 100 ft. Even though the BARO setting will be 29.92. OAT is at whatever I set it on the last flight. Truly strange.

In any case, I'm not concerned about the Aspen installation. Just curious.

Picking the plane up tomorrow at Southtec. Will post a PIREP on all the systems after I’ve flown behind them for a few hours. I’m sure it’ll be quite a different airplane than before!

Attached a couple photos Glenn from Southtec and Gary from Carolina Avionics have sent me.

One bit of negative is that with the Aspen surface mounted I have to take a bit more care on entry/egress. The bezel is about 3/4" deep and that extra bit means the two knobs are that much further into the entry space. I don't think it's possible to flush mount it in the "small" panels in the '02-'04 six pack birds.

Mine really shines when driving the autopilot using GPSS But even hand-flying approaches is marginally easier with the deviation indicators being rendered on the attitude display.

I'm undertaking some significant (for me) avionics upgrades. Pulled the trigger on a GI-275 ADI with SVT/FPM today. They (Freedom Avionics - KLYH) are backed up to February but since it's a "small" (nearly 8 AMUs) job they think they might be able to fit me in before the end of the year. I'm keeping the HSI, so they are going to have to find another place besides the right wing for the magnetometer (GMU-11). I'm also exchanging my Garmin GMA340 audio panel for a GMA345 to get Bluetooth connection to Foreflight on my Ipad and virtual spatial separation for Com 1, Com 2 and passenger audio. Finally, like many of you have I'm upgrading my wingtip lights to Whelen Orion 600 LEDs (not needed but got a good price at Oshkosh.) Will give everyone a PIREP as things are completed and tested. Bernie

So after deciding not to go with the GI-275 ADI, I picked up my DA40 from Freedom Aviation today with my new Aspen 1000 EFD with Synthetic Vision. Did a limited test flight which did not reveal any issues. It took them a month but that included the holidays and the lead technician coming down with COVID. Freedom was able to put the RSM inside the wing. I lost OAT/TAS/Winds but saved several thousand dollars. They also pre-wired it for ADSB data from my GDL-88 in case I chose to purchase the unlock. I agree with Rich that it tends to stick out some, but its not that bad.

Baro corrected VNAV?

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Rich wrote: ↑Tue Dec 22, 2020 1:22 am In researching all this stuff I came across something curious. The GNS units can accept various additional inputs via ARINC429 stream. This includes straight pressure altitude, baro-corrected altitude, and heading. It also appears that the Aspens could possible supply this info to the GNS units.

OK, but what would the GNS unit do with this data were it supplied?

Lance Murray wrote: ↑Mon Jan 31, 2022 6:45 pm Baro corrected VNAV?

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Rich wrote: ↑Tue Dec 22, 2020 1:22 am In researching all this stuff I came across something curious. The GNS units can accept various additional inputs via ARINC429 stream. This includes straight pressure altitude, baro-corrected altitude, and heading. It also appears that the Aspens could possible supply this info to the GNS units.

OK, but what would the GNS unit do with this data were it supplied?

There's no indication anywhere in the manuals that is does Baro correction of any sort. And the VNAV function is not the same thing as in other systems. It's merely a planning tool.

Isn't "baro-corrected" altitude just "MSL" altitude, i.e. in contrast to pressure altitude? The "altimeter setting" [QNH] setting in the Kollsman window (or glass panel equivalent) is what "corrects" the altitude to MSL.

"Baro-VNAV" is something entirely different. It's what is used by specially-equipped non-WAAS aircraft to create the glide path in GPS approaches with LNAV/VNAV minimums. These are the GPS precursor to WAAS/LPV for approaches with vertical guidance (APV). It's extremely rare in GA aircraft.

G1000 aircraft with SBAS/WAAS uses that to calculate the more precise lateral & vertical guidance when flying an LNAV/VNAV approach. However, you'll only see this happen when flying an approach that LNAV/VNAV minimums but no LPV minimums. If there is an LPV option, the G1000 will pick that. If WAAS goes away, then it falls back to LNAV, not LNAV/VNAV.

chili4way wrote: ↑Mon Jan 31, 2022 8:52 pm Isn't "baro-corrected" altitude just "MSL" altitude, i.e. in contrast to pressure altitude? The "altimeter setting" [QNH] setting in the Kollsman window (or glass panel equivalent) is what "corrects" the altitude to MSL.

Correct. The mystery is what good does it do to have this fed into a WAAS GNS. I can find only one obscure reference where it might have some effect. This is in reference to an example missed approach:
VNAV was in fact something that came out pre-WAAS, where with the right gizmos you could get vertical guidance using baro altitude. Even in the WAAS era, there was a period where the FAA prohibited the navigators from providing vertical guidance for LNAV or LP. But that's long past.

Rich wrote: ↑Mon Jan 31, 2022 7:24 pmAnd the VNAV function is not the same thing as in other systems. It's merely a planning tool.

I may be confusing your reference to VNAV with VNV in the GFC700. I think your reference to VNAV may be in the GNS units. For clarity to those with, or wondering about the GFC700, its VNV function is a calculated descent angle/path plotted by the Flight Director and which the AP will fly to reach the designated point at the specified altitude.