I suffered heavily from the leans during incompleted IFR training several years ago. I learned to fly through it. I’m surprised to hear some people never feel it. I think that’s alarming because it’s a sensation you want to know and understand.
I agree with others: best to go on instruments when in marginal VMC. I also prefer instruments when over water without a horizon line.
Never been a problem to me, but I had vertigo once during my IFR training flying over the (blue) SF Bay with foggles. Seeing the blue water below me out of the corner of my eye was extremely confusing and I had to resist very hard to keep the blue side down 
Peter wrote:
How many people get the “leans” when in IMC?
Got them twice, lasting perhaps 2-3 min. No super serious, but could definitely think we would turning while we were straight and level.
Peter wrote:
I almost never do.
I seem to have the impression that you fly a fair bit IMC, yet you have never had even the slightest feeling that the AH might be just a little offset? Try flying some partial panel in actual IMC… (preferably with a safety pilot)
I’m not an IFR pilot, but I had to do some flying under foggles as part of my PPL. The very first time I did it, I got the leans (didn’t know what it was then).
I can clearly remember thinking “The AI is broken! It showing the completely wrong angle!”. I was just about to say this to my instructor when I realised that if such a thing had of happened, he’d have said so to me quickly because he had a nice clear view outside.
I worked very hard to fly on the instruments that day, and was as white as snow and totally drained when we landed (only took the foggles off on short final).
I’ve never had it since in any training under foggles, but it’s a lesson well learnt and for that alone was well worth while!
The only time I ever had those was during early sessions in a full motion flight simulator, especially during taxi on the ground (I still must actively fight those sensations every time we go for new simulator training). I can’t remember ever having them in the aircraft. But this is probably because I started IFR flying very early in my training.
Only really once during IFR training at night in moderate turbulence with storms and lightning flying from Canberra to Sydney. Really bad though and while the instructor didn’t need to intervene I was sure the instruments were wrong.
I have twice – once during training right after unusual attitude recoveries and once for real: In December, at night, with insufficient heating, over the Cairngorms in Scotland – the cloud tops were strongly slanted to the right and I found the visual illusion impossible to ignore. Fixed by going 100% eyes in the cockpit.
Once during training, and it was quite severe.
I did most my IFR training at night as it made it more realistic (the sunlight tracking across the panel I felt gave me too many visual cues, and there was always a bit the hood didn’t quite obscure properly)
I was doing some approaches at night, and we were on our last one (ILS into KGLS/Galveston-Scholes). My safety pilot had been screwing with me a bit by moving the seat – he is quite a heavy guy and the seat in a Cessna 172 moves a long way, so he subtly moved his seat all the way to the back of its travel, or nearly to the front, whenever I got the aircraft settled on the glideslope to add a “realistic distraction” and it created a very noticeable change in trim. I didn’t know he was doing this, of course.
So what would have been an easy ILS turned out to be rather more challenging.
Then to add to that, about a mile from the threshold you go over the I-45 causeway (Galveston is a barrier island off the coast of Texas, joined by the freeway) and it’s illuminated. Through the little corner of the windscreen the hood doesn’t quite block, I saw three streetlights which my mind suddenly decided were part of the horizon – and if this were true, we were in a 70 degree banked turn to the right. In fact, the aircraft was wings level. Since we were at 400 feet or so at the time in the late stages of the ILS, this resulted in very quick mental overload – the “lizard mind” was utterly convinced we were in a 70 degree bank and about to die, and it’s very hard to drown out its “shouting” while continuing to fly the aircraft from what you know is actually true from your instruments. It became very hard to maintain my scan and stay on the localiser and glideslope (especially as its quite sensitive that close in).
To add to that my safety pilot had re-tuned the NAV radio while I wasn’t looking at it so to screw up my missed approach procedure if I forgot to ident it. Of course, after all of the above, once the approach was over and we were flying the miss, I completely forgot about identing the navaid till I wondered why I wasn’t intercepting the radial I should have been.
I’ve not had it more than once, I think… At least not so severe that I remembered it.
