So I’m working on my PPL in a 172 while my M20 is in pieces all over the country for various reasons. This Sunday was the first practice under the hood. I have previously flown in IMC with an IIFR certified instructor in the right seat and so this wasn’t the first time under instrument. I did fine that time, however, this Sunday was a different experience.
Under the hood I was really struggling to hold the heading. If I put the wings level in the AI the DG would show me turning one way. Then I would fix it. Wings level. Then it would say I was turning the other way. I commented to the instructor that I suck this time and I don’t know why. It started to mess with me. What my body felt, what my senses told me, what logic was telling me, didn’t match what I was seeing. Then the AI started telling me I was rolling to the left and I started to correct it, but it didn’t add up. I told him “something’s wrong, I don’t like this” and panicked a little even though it was VFR with the instructor in the right seat. I lifted the hood briefly and saw I was still wings level. 1 Mississippi, 2 Mississippi...,5 Mississippi and the Instructor says “wow, look at your vacuum gage”. IT was reading zero and the AI was a tumbled sideways and down (basically the opposite of what I would have done to try and save it)
There are some valuable lesson here as with many things that happen to go wrong that don’t kill you....I don’t think I would have survived that in real IMC, especially if alone. But now I’ve seen exactly what a vacuum pump failure looks like. It’s subtle at first as the gyros spin down. They will kinda work, the errors will get worse...then they fall apart like a top running out of spin.
I tried flying partial panel a little bit after and boy that would be tricky with just a T&B and compass for wings level. Survivable in a straight line until I’m clear of clouds but that’s about it at my current skill level. So this further enforced for me the fact that I’m not going IFR until I have an electric AI as a primary or backup. I want a way to quickly double check that the primary is correct...not just for when the first one fails because once you realize that it failed, it might be too late.
This trip was my first time flying with only a Whiskey compass...what a terrible instrument! I now see I need to focus more on learning how to use it better or I need a vertical card. Dreadful thing. I have a lot more respect for our flying ancestors and understand better how Amelia probably vanished.
I also learned that I hate vacuum gages. I would much rather have the idiot light like my 66’ E. That light would have warned me to not trust the gage and this AI didn’t have any flags which would have also worked.
My take-aways, in summary:
1. Don’t fly IFR if your AI doesn’t have a vacuum loss flag or your panel only has a vacuum gage
2. Vacuum pumps fail...a lot apparently, don’t bet your life on it not. Have a damn good plan B and a clear way of knowing when to take it.
3. If the gages don’t add up, maybe fall back on the secondary while you judge if the primary is safe to follow, don’t let them fly you into the ground if multiple sources aren’t agreeing. I did decide it was wrong this, but panic boiled up. It wouldn’t have ended well. (I’m pretty sure this type of guidance is in IFR training?) This also directly conflicts with the idea of trusting your gages in IMC. Having this doubt in your mind might be really bad actually.
BTW, before you beat me up, I only have about 25hrs of VFR training with interruptions as my Mooney failed on me again and again. This was my first time under the hood...I’m still a noob.
Comments on what else I should take away are welcome but don’t try to talk me out of hating a mag compass. Lmao.