Other Bob: I strongly disagree with the ?no switch? approach. If the switch fails, you lose the full functionality of the autopilot. This should be an inconvenience, at worst. But should the primary efis fail, you might (depending on back ups, etc) really want the autopilot to work, including a gps approach capability.
Not entirely correct and options may be limited, but there are options.
I didn?t lose an efis, but I did lose my arinc adapter on an IFR flight. My GTN650 was still working fine and I could see if I was on the intended course without an issue. I still could use the autopilot as well, except nothing was talking to it. I had complete manual control. I had no problem with following the course display on the GTN 650 manually. I had no difficulties flying a standard step down gps approach. Of course you can always hand fly the approach too, with guidance from the certified navigator.
I will admit, it?s not something I would want to do to minimums, but it?s an option. Anything below MVFR and I would do a direct route to the nearest vfr alternative.
I also happen to have three AFS screens and a Trutrak Gemini in my panel. While losing the PFD would be inconvenient, it?s not the end of the world.
The OP also has a MFD with a non-certified GPS connected. While technically not legal for IFR operations, it can provide great situational awareness and provide position information on a moving map. I don?t know about the WS capabilities, but I can display an approach plate, sectional, or IFR chart on my AFS 5500 MFD and my position will be displayed on the plate.
As long as the certified gps is operational, the display is within the required viewing distance, and you see the NAV screen, you?re still legal.
This is no right or wrong, or my solution is better than your solution, conversation. It?s really about doing the due diligence required for proper panel design and then ensuring you practice all the various emergency procedures until you?re proficient.
Questions to ask:
1. Is vfr or IFR a requirement?
2. On paper, fail each device in your panel. What is your plan b to mitigate that device?s failure in the air? In a real situation this is where the Vizion?s hold track and altitude button buys you think time.
3. If there isn?t an obvious plan b, then what do you have to change in you panel design to give you one?
4. Run through other failure scenarios that make take out multiple devices. I.e. electrical issues
5. If you answered vfr to the first question, this is all academic but will help you understand your panel limitations better.
6. Document all your various plan b?s in you POH.
In a recent IPC, I had a very competent CFII and corporate pilot start failing devices on me. He gave up after about 15 minutes. My panel design took those failures into account, each one was documented in my POH, and I had practiced flying in each failure mode.
At some point, you do end up chasing your tail with too much redundancy. Too much redundancy can also cause complexities that complicate the situation. Everyone needs to determine where that fine line is in their own panel.
