Forced Landing Checklist, Master, Stall Warning

Just doing some "armchair flying" and going through the forced landing checklist in my head. I haven't tested or traced this on the wiring diagram yet but..

When you secure the Master, pretty sure you loose the stall warning tone, do you also loose the AoA tone?

If your -12 has an EFIS installed, it's backup battery will keep it and all its warnings alive. However, you will probably have to press a button to switch to the backup battery, when the EFIS senses it lost power.

Sorry, I should have been more specific. My 12 has a Dynon HDX. The backup battery will automatically power the system in the event of aircraft power lost or if you turn off the master, however you must tell it to stay on beyond 30 seconds.

I have both an AoA system and a mechanical stall warning vane. Both come on during normal ops, i.e. stalls, slow flight, landing.

I'm pretty sure the stall warning audio is powered through the radio. If I turn the radio off, I don't have an aural stall warning tone. Also sure the radio is not powered with the master off. (could be wrong, I'll test tomorrow)

The AoA system is part of the ADHARS system and is powered by the backup battery. The question here is whether I get aural tones if the radio is not powered.

All this leads to this potential conclusion: If you are expecting to use the AoA system or stall warning tone to assist you in a minimum energy forced landing, you may not have them if you secure the master prior to touch down.

Tacco said:

The AoA system is part of the ADHARS system and is powered by the backup battery. The question here is whether I get aural tones if the radio is not powered.

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No, it wont. But that doesn't mean you don't have AOA info.

Tacco said:

All this leads to this potential conclusion: If you are expecting to use the AoA system or stall warning tone to assist you in a minimum energy forced landing, you may not have them if you secure the master prior to touch down.

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The AOA depiction on the screen will still be active. The visual stall warning indicator will as well. You just wont have aural info.

rvbuilder2002 said:

No, it wont. But that doesn't mean you don't have AOA info.

The AOA depiction on the screen will still be active. The visual stall warning indicator will as well. You just wont have aural info.

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Scott is correct, as usual.

Once you are flying, turn off the radio and do a bunch of stalls and slow flight. This will teach you what the plane feels like at low airspeeds.

The HDX should stay alive when switching off the power supply. It realizes it is in flight and won?t shut down then. Only on the ground it shuts down after 30 seconds "decision"time.

Thanks guys. Again, just a little armchair flying. Totally agree that knowing the aircraft's slow flight characteristics is the first thing. Pretty comfortable there. Just was wondering how the system behaves in this situation. Another piece of knowing your airplane. Practically speaking, I don't think I would be hawking anything but the airspeed. Head out of the cockpit mostly. Cant see myself even glancing at the "micro" AoA display. Now I won't have that stray thought "Why am I not hearing the AoA tones?" at a time when every second of focus counts.

Btw, yes, the Dynon system will not power down in flight by itself if you loose aircraft power (or turn off the Master). However, you do have to answer the cue "Power down Yes or No" if you want the normal menu back. The only reason to answer "Yes" would be if you had two displays and want to power one down to save the battery.

Tacco said:

Practically speaking, I don't think I would be hawking anything but the airspeed. Head out of the cockpit mostly. Cant see myself even glancing at the "micro" AoA display.

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I think it is not by accident that the AOA indicator is right beside the Air Speed tape.
A fast glance at the air speed basically gives you both at the same time.

Your scan must be more comprehensive than mine Scott. It is easier for me to see it when I'm full screen and don't have the map up. And by see it, I mean "process" it. I've gotten used to flying the tones. Last time I see the airspeed is just prior to crossing the threshold. At solo weights, that's usually about 50 kts, AoA tones kick in at 47 kts the way I have it set up. Thanks to the Dynon data down load capability, I can see my touch downs have been consistently 44-42 kts about the time the stall warning starts whining. By the time I pass the 1000 ft marker, I've been in taxi mode for a while. I think the aural tones have spoiled me.

Tacco said:

Your scan must be more comprehensive than mine Scott. It is easier for me to see it when I'm full screen and don't have the map up. And by see it, I mean "process" it. I've gotten used to flying the tones. Last time I see the airspeed is just prior to crossing the threshold. At solo weights, that's usually about 50 kts, AoA tones kick in at 47 kts the way I have it set up. Thanks to the Dynon data down load capability, I can see my touch downs have been consistently 44-42 kts about the time the stall warning starts whining. By the time I pass the 1000 ft marker, I've been in taxi mode for a while. I think the aural tones have spoiled me.

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I do agree that I think Dynon really nailed the user interface with the tone output. I am looking fwd to the day when AFS (what is in my panel)rolls that into their product as well.