Questions after WAAS upgrade ....

I would fire him.

He is clueless.

What he is saying is that Avidyne did a totally cynical “our customers are idiots” move of providing two buttons which do the same thing and have different text labels!

They are algorithmically identical when the navigation source is GPS (selected on the GNS). That was the scenario this statement applies to I guess. With other autopilots the behavior of GPSS vs NAV with a GPS source is very different between GPSS in essence simulated HDG whereas NAV uses CDI which means overshoot on turn, overcorrect, stabilize, etc. With that distinction in mind the DFC can be confusing and hence the statement that they do the same (for GPS!).

The modes NAV vs GPSS are very different when the navigation source is LOC. That is neither hard to understand nor hard to verify so kind of pointless to argue about it

In my experience the Avidyne manuals make Garmin look brilliant and that is saying something.

As I said in an earlier post, with the DFC90 there is no reason to use GPSS instead of NAV. While there is a difference, that difference only reduces the utility of GPSS. Achim is the only person I know who makes use of that as a feature!

Flyer59 wrote:

There is no algorithmic difference between the two in the DFC90

The devil is in the details. That statement only says that the DFC90 will process input the same way regardless of input source, but it does not say that the input source is the same!

Edit: I see that Achim wrote essentially the same thing.

Could we make this a new thread, please?

Of course – anybody and everybody should start a new thread for a new topic

That statement only says that the DFC90 will process input the same way regardless of input source

It’s still a long way from saying the two buttons do the same thing. They can under certain circumstances. For example, in a certain system configuration, I could demonstrate that my KFC225 flies the same track when in NAV mode (with ARINC429 data) and in HDG mode (if there is a roll steering converter installed, which would be slightly pointless if there is already an ARINC429 connection to the AP).

Simple statements are often really dangerous, but modern avionics are nontrivial.

Flyer59 wrote:

I have a “Lightning Error” message now before the Stormscope initalizes … goes away though.

Sorry missed this one. Did have that before. Switch of the GNS after you get this message. Switch it back on. Does the message turn come on again? Likely it is not. Then the boot / startup sequence is just so the GNS is slightly faster then the stormscope.