On the subject of manual flying skills and training, this is an issue that I finally managed to rectify in our company for the 225, shortly before I retired. It was a struggle though! Basic problem is that for 6 monthly checks, the rules said that you must fly manual approaches. That is, approaches with full autopilot functionality in terms of attitude hold when cyclic release, artificial stability when cyclic operated, co-ordinated turn, heading hold when wings level etc. But not allowed to use the upper modes. Crazy, because that scenario is just about impossible.
So a lot of training time had, by CAA edict, to be spent manually flying. So no time left to properly explore how best to use the automation, how to deal with partial automation etc. Crazy! The whole industry, including the CAA, is culpable for this accident. But unfortunately they get away with it and just blame the pilots.
As I mentioned I finally persuaded CAA to allow fully coupled approaches by default for OPC /LPC, albeit with some partial (and hence realistic) malfunction thrown in for one of the approaches. It is just crazy to train for stuff that you never have to do in reality, and to not train for the stuff that is your bread and butter. And to take the view that certainly prevailed at the time with CAA and EASA - that real pilots flew manually, anyone using the coupled modes was cheating.
Been away for 7 years now, it would be great to think things had changed a bit but I rather doubt it!
Oh and in summary, they should have been using IAS mode. Maybe with Vs on collective, or not, doesn’t matter too much but the key thing was to have IAS engaged. If they had done that, the accident wouldn’t have happened. But nothing in CHC ops man at the time that told them what to engage or the perils of not engaging IAS.