I lost my (vacuum) AI twice three years ago, all in VMC. Once I had to continue flying into heavy IMC into an ILS to 200ft. Fingers crossed, but it never happened again in the subsequent 200 hrs. I carry adhesive round pads in the flight bag to cover instruments for such eventuality.
The above thoughts and my experience make me really glad our 210 has two AI’s (one electronic one steam ) plus an electric T&B in the pilot’s primary field of view (plus another electronic on the RH panel plus on the yoke ipad with remote AHRS) . What I am missing is two of them driving the A/P , perhaps for a future upgrade.
I am convinced this problem is a couple of orders of magnitude worse in IMC than VMC, though. The accident flight was mostly VMC…was that the case in Emir’s reports?
Emir wrote:
I can easily imagine scenario for this: failure of some instrument (autopilot, MFD, PFD) which itself is not an emergency, pilot switches to hand-flying, asks for return vectors, tries to figure out the reason of the failure, currently in IMC, bank increases without being noticed, at 70 degrees of bank wrong recovery action, the aircraft goes to spiral dive and overspeed, it’s non-recoverable anymore and airframe possibly disintegrates or aircraft hits the ground under very steep angle with speed over 300 KIAS and sink rate over 15.000 ft/min.
Thanks for describing it…is the PC-12 more prone to this type of scenario than other types? No secondary AI in Primary FOV? Too high roll rate available? Neutral lateral stability?
I think one has to distinguish loss of control on full power vs loss of control in cruise/low power, I am sure they are not the same thing? the first thing you need to do right after losing control is to cut power, it’s the same thing whatever it’s spin or dive or left or right turn, high or low pitch, 5m or 5k aircraft
Having natural or artificial horizon is a nice to have to understand what is going on but you gotta throttle it back first irrespective of it’s attitude or what is going on, the PC12 has 1400hp in front, that takes one straight to hell quickly compared to a C172 with 160hp, with engine at idle they just fly the same way, actually like any other certified aircraft…
Some of the loss of control could be induced by the layers of complexity in aircraft or procedures, some automated aircrafts tend to separate the pilot from what is going behind at the basic level (bank, speed, pitch), under that smooth safe looking facade we are still putting our and family lives at the hands of some engineers and at mercy of basic pilot errors
I used to fly on legacy auto-pilot and take it by hand when it struggles, losing the aircraft was not on the menu as I continuously watch it and takeover, after getting used to GFC700 things were just smooth and way too much comfortable, I did takeoff once, plug it and it it was disconnected during departure climb, I did not notice it until ATC asked to confirm my heading, since then I started treating it like KAP140….
We all hand fly during the IR test, it’s easy you are likely to be flying in fair weather under the hood, two pilots, familiar airspace, doing procedural route as planned where you know the heading & altitude at each point of the flight, with pilot having top human performance
This is not the case in real life, with family & work distractions operating in hardcore weather tactical ATC vectoring & assigned altitudes until you get dumb 
having an autopilot and using it greatly help with workload and should be part of normal flying, it will be 100% dumb not to use it, but one still need to back it’s usage with good hand flying skills for emergency…
Know to use automation to fly perfectly and know how to use hands to stay alive
bq.Thanks for describing it…is the PC-12 more prone to this type of scenario than other types? No secondary AI in Primary FOV? Too high roll rate available? Neutral lateral stability?
All PC12 vintages have a standby AI in the primary FOV, lateral stability is positive (especially with YD on). Roll rate is low.
Ibra wrote:
the first thing you need to do right after losing control is to cut power, it’s the same thing whatever it’s spin or dive or left or right turn, high or low pitch, 5m or 5k aircraft
Well… In a nose-high abnormal attitude, your first priority is getting the nose down, not cutting power. Cutting power first could provoke a stall. Indeed, I would not cut power at all, rather the opposite once the pitch has become more reasonable.
Cutting power first could provoke a stall.
Do you mean if I cut power first and second push the nose things will go badly? the problem is you don’t know if you are in high nose attitude in the first place, remember you are disorientated, you could be -25deg down thinking it’s +25deg up, in both cases you better throttle it back…
I think it’s misconception to link power to stall, you will stall if you cut power AND pulled the stick, just as much as you stall with full power AND pulling the stick, actually quicker with power than without
I can’t see why cutting power cause stalls, gliders do without all the time…or you mean an engine failure during climb in IMC is irrecoverable?
In pistons, if the nose attitude is high than 20deg you will stall with power or without it, when it happens you better have power off, power is not required to recover a wing from stalls…
If you are talking about maintaining height that I agree, you will need power, but as far as dealing with loss of control we are talking about maintaining speed & bank angle, this is better done without power !
The was a lot of emphasis on use of power for recoveries with minimal altitude loss, but this is being quietly removed as it created a bunch of pilots who tend to rely on power to get out of a dive or spin…
I think the high nose attitude recovery for stuff with big engines involve reducing power (with underwing engines) or banking to allow for the nose to come down, different physics of course but the aim is the same keep AoA under control and forget about maintaining height
In unusual attitude recovery the 1st thing you look at is the speedo and
Then level the wings. But this could overload the wings if the speed is too great, so one may need to push down initially.
Ibra wrote:
I can’t see why cutting power cause stalls, gliders do without all the time…or you mean an engine failure during climb in IMC is irrecoverable?
We’re talking about abnormal attitudes. A climb attitude is not an abnormal attitude. If you cut the power with constant nose-high pitch the aircraft will immediately accelerate downwards leading to an increase of AoA. If the nose is high enough, this could very rapidly lead to a stall. Probably not at a pitch corresponding to Vy, but again, that is not an abnormal attitude.
Just for fun, I googled “recovery from abnormal attitudes” and looked at the first four hits. (At least three were reputable web sites.) One was unspecific as to the exact action (“follow the AFM…”), but all the other three advocated increasing power in a nose-high abnormal attitude, although they did differ in the order of increasing power and lowering the nose.
If you cut the power with constant nose-high pitch the aircraft will immediately accelerate downwards leading to an increase of AoA
Won’t the aircraft fly at the trimmed speed i.e. if you cut power during a climb at say 100kt, it will now descend, at 100kt (approximately)?
Peter wrote:
Won’t the aircraft fly at the trimmed speed i.e. if you cut power during a climb at say 100kt, it will now descend, at 100kt (approximately)?
In a stable situation, maybe. But your not in a stable situation – the transition to descent at 100 kt won’t be instantaneous. Also trimmed speed is affected to some extent by power – particularly if you go from full power to idle.
