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In solid IMC suddenly I didn't know which instruments I could trust.

I only know it for the DA42, but there you can pull the AHRS and ADC CBs separately and that should have helped to prevent the erroneous output. However I always thought that with the BISTs, these devices are more likely to show red crosses when they find any error instead of trying to produce data which is garbage.
Compare this picture to see the AHRS and ADC CBS in the top row:

Regarding not using the CBs to pull power during training, I think this is due to the fact, that the CBs have a cycle limit which is meant for regular use. E.g. these have a mechanical limit of 5000 cycles, other limits lower, so imagine a CPL/IR school where the breaker is popped twice everyday for training, then design limit is reached after 7 years. I know this is still long, but I learned that CBs shall not be used as a replacement for a switch.

P19 EDFE EDVE EDDS

@Peter thankyou for commenting that I did well, I wish that were true. I was very lucky in that I happened to be flying with a very experienced examiner in the right hand seat and ATC were as usual very helpful.
I have now had a couple of days to reflect on the flight and to consider the advice on here as to the actions I could have taken, remember what was going through my head at the time, what I did and why, and where I could have done better etc.
Pulling circuit breakers, might have alleviated the distraction problem I did not do it why?
1) I didn’t think about it.
2) If I had thought about it I don’t think I would have had the spare mental capacity to check and find the right circuit breaker to pull whilst trying to keep straight and level in high gusting winds, trying to maintain altitude with strong up and down air currents and also to try and figure out how to tell what heading I was actually heading and whether it was the right heading in the first place.
3) I don’t think the examiner would have suggested it as instructors and examiners in France have been advised not to pull circuit breakers in flight (incidentally they have also been advised not to reset a breaker even though the flight manual suggests you can reset once)
So what could I have done better? The main thing probably would have been to recognise, more quickly that I had all the information I needed even though the scan would need to be very different. On top of the PFD I had next waypoint, distance and bearing to it info, on top of the MFD I had track and ground speed info, active leg, I had a magenta line and I could call up all the flight plan info. I had a compass which
in the DA42 is on the right of the standby AI and altimeter all along the top of the panel with the compass being more aligned with the front passenger seat.
The second thing would have been to compute this information better and quicker. Basically the calculations I needed make were roughly equivalent to flying an NDB hold and approach without a DI (ie using the compass instead).
A few years of flying glass cockpit have made me complacent I had forgotten these skills. I had also forgotten as I think I have already mentioned that the compass turns in the opposite sense to a DI or HSI. This resulted more than once in starting a turn to the wrong direction to that required, it then became difficult, time consuming and brain busting to get back on track.
I had also forgotten my scan and partial panel training. My eyes would linger on the compass to long as I turned from one heading to another, instead of turning and counting 1 second 2seconds 3 seconds etc before looking back at the compass to see whether I had actually achieved a ten degree turn.
So basically I should say my mind just went blank for what seemed like forever and it took several minutes before I started to put things into place. Some things like the compass turning in the opposite direction I kept having problems with for the rest of the flight.
Fortunately the examiner would say you need ten degrees the other right or the other left as necessary.
ATC gave me simple cardinal point vectors, 90 degrees, 360 degrees etc, easier to recognise on the compass.
Would I have called a Mayday if I was alone on board? Maybe. I can’t answer that question. I think I might have asked ATC for vectors to a nearby military field and to see if they could negotiate a, PAR approach there. I really don’t know, I think these sort of decisions are made at the time and second guessing is difficult.
Similarly if I had been alone in a Cirrus would I have pulled the chute? Again I don’t know. I would wonder where I would end up with 83kt winds.
What I do know is that I shall be doing some further training in the old ways:)
By the way I did revalidate my MEP, MEIR and my SEIR with the same examiner.

France

I think with the G1000 going wild you should keep it as simple as possible. Fly the plane first.
The backup instruments are there for a reason. You can still fly the plane.

The navigation part can be handed over to ATC. They can guide you to an airport with VMC conditions.

The problem with i.e. Cirrus is that the backup instruments are down low just above your knees, while the magnetic compass is above the wind screen.
That’s going to be a challenge flying limited panel with the head movement needed to keep the compass in your scan.

Instrument failure in IMC is a real emergency. If you can’t fly heading using compass, tell ATC. They can instruct you to turn left / right or keep level.

The G1000 has its quirks. I once lost both heading and attitude indication because GPS was not working.
Fortunately that was in VMC. See https://www.euroga.org/forums/maintenance-avionics/3097-g1000-gps-failure-results-in-loss-of-ai-and-heading

I was a flying a G1000 DA40 in North America and had the same happen, in solid IMC, when on an ILS – except I also lost the localizer and glideslope. Lijke you various of the G1000 units were changed in an attempt to fix the issue, but In the end it turned out to be simply bad crimps from the magnetometer (there are 4 sets of connectors between the magnetometer and the AHRS in a DA40). It was “interesting” when this happened; it was the day after I passed my IR checkride so was current on partial panel. Also like you I used the backup AI, compass and MFD to get down [GPS continued working as it should, fortunately].

EGGD Bristol, United Kingdom

@gallois Is this what happend to you?


EDDS , Germany

@eddsPeter I would be very interested to see the video you asked about but I can’t get the link to work, and the site also doesn’t work if I type it in manually. But I am an IT dunce.

France

@gallois wrote:

but I can’t get the link to work, and the site also doesn’t work if I type it in manually.

Does it work better with this



[ link fixed – you can’t do clickable links to vimeo or youtube videos because the text processor expects to see the actual URLs so it can place the video into the post; see Posting Tips ]

EDDS , Germany

@eddsPeter thanks for your patience,. Well it was worse than that, it was a g1000 PFD , so bigger and covering more of the eyeline, which did what was in that video for possibly 3 to 5 seconds then it would switch to a screen full of crosses for a few seconds, then all looked to be displaying normally for a few seconds, but it wasn’t, then HDG with a orange/red cross through it would appear and the AI would creep slowly left or right (very slowly) so that I became convinced I was in a slight turn, then after a few more seconds everything would go to something like the screen on the Aspen in the video.
It was difficult to not have hope that everything had righted itself every now an again.
The flight computer showed all working perfectly.

France

This is why a turn and bank is a very useful instrument still, just to verify that the backup AI is correct. And should both of those fail, you can keep level flight on that.

Stark 1-2-3 Method

Last Edited by AdamFrisch at 22 Jan 15:50
29 Posts
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