John R. Copeland wrote:
If nobody else runs the test before I get a chance, I'll report back when I do.
I think you're too deep into speculation mode when you suggest baro input
might contribute to determination of lateral position.

Certainly deep into speculation, since AFAIK all the navigation algorithms are
proprietary, ... or maybe they are published as part of some certification
process, anyway, I've never seen them.

However it seems clear that baro-aiding is incorporated into TSO C129
navigators, which offer no vertical guidance. It's hard to imagine why they'd go
to the (considerable) trouble to have a baro-aiding interface if the baro-aiding
didn't add to the navigation solution.

Until I see some test results, I lean more toward thinking the CNX-80
may be relying on WAAS-augmented geometry for VNAV guidance.
It might be very ILS-like in that instance, where the baro setting
affects the DH(DA), but not the glide path.
---JRC---

"Dave Butler" wrote in message ...

John R. Copeland wrote:

I could test that by setting a grossly inaccurate Baro reading,
and watching the actual altitudes it steers me toward.
I think I'll try that next time I get a chance.

I'll admit I'm guessing here, and I'd like to know exactly how the baro input is
incorporated in the navigation solution, but I suspect the baro altitude is
incorporated into the solution in a similar way to having another satellite in view.

IOW, with 5 satellites in view plus baro input, the navigation solution has 6
equations with 4 unknowns (3 dimensional space plus time). If that's the case,
the baro input participates in the lateral position determination as well as the
vertical. I suppose they could "weight" the effect of the baro input since its
precision/accuracy are different from the satellite inputs.

In TSOC129 units that use baro-aiding, there's no vertical guidance, yet the
baro input is incorporated in the navigation solution somehow.