JIMMY 16 - I think your post is absolutely on the mark.
For those posting opinions on autopilots, stating they disconnect the crew from the task, you clearly have not used modern DAFCS equipped machines.
In an AC such as EC225, flown by a properly trained crew with a complete understanding of the DAFCS, the FADEC and the display system, it is impossible for them to sit there wondering "what is it doing now". When there are no abnormal indications, it is doing exactly what it has been designed to do.
If the crew are not properly trained, expectation and delivery may not marry up.
In a modern DAFCS, use of the terms 3 AXIS and 4 AXIS coupling are no longer relevant. It is far more relevant to refer to Fully Coupled OR Mixed Mode flying.
Mixed Mode flying MEANS that one or more of the AXIS (vertical, lateral or longitudinal) are in the custody of the pilot. Knowledge of the display indications make it clear to the pilot which axis he is responsible for. This is a simple concept that is far too often not fully trained and ingrained into the crew.
During automatic mode engagements or switches, such as an ALT.A capture, where V/S is replaced by ALT, it is important the crew recognise, when mixed mode flying, which AXIS, and thus which flight control(s), are in their custody and finally, if they move that control(s), what effect it will have on the flight path.
Of course this is significantly simplified by flying fully coupled. Combine fully coupled mode with DAFCS complete flight envelope protection and now the pilot and passengers are protected from errors in bug selections. Add in terrain awareness displays, with aural and visual warnings, a radar to validate the real world, datamap overlay and now the lateral flight path is also protected. All these systems are fitted to the EC225/175.
In the first EC 225 inadvertant ditching close to the ETAP, the Commander failed to deploy the DAFCS modes AT ALL and the crew deselected the aural terrain warnings. I do not know why! However I would hazard a guess that Commander fits the profile of those of you posting on this thread who state they would decouple and fly manually when things get bad.
For those of us fully trained in modern DAFCS, and involed in teaching these concepts, decoupling close the surface is normally associated with very poor training and/or poor core flying skills.
The L2 has an extremely capable AP. it is a huge step forward from the previous generation. However it has its limitations such that all minimum visibility approaches should be flown fully coupled and NOT in mixed mode to ensure safety. This is required because, unlike the EC225, there are no flight envelope protections. Having flown the L2 for 3000 hours it is a very safe, very competant helicopter in the hands of a well trained, competant pilot. If his operating rules allow latitude for MIXED MODE FLIGHT approaches the first hole of the swiss cheese has already lined up against him.
However, the L2 is not an EC225. The single most significant difference is that in the L2 the Longitudinal Axis always takes priority over the vertical axis. Thus in the cruise, MIXED MODE flight is deployed to avoid unintentional descent under IAS longitudinal prioritisation. However, failure to mandate fully coupled approach procedures when the IAS does not defeat the power available, and by this I mean CAT A ICAO speeds, provides options of mixed mode flight for the crew, and this practice is complex and potentially dangerous at low speeds (as needed for a safe visual transition at MDA/DA), if the crew do not fully understand the axis in their control when in mixed mode flight.
The AAIB reports strongly suggest the helicopter was being flown in Mixed Mode, close to the surface. If you are an offshore pilot reading this, and you do not recognise how dangerous this practice can be, go to your TRI and ask to be retrained. If you a TRI/TRE allowing this practice to occur by pilots in your operation, take all steps you can to outlaw this practice.
Finally, for the hysterical uninformed multitude who bleat on that the pilot is no longer in control, know this, in all EC civil helicopters, no matter what the AP is doing, the pilot always has the option to place hands and feet on and "fly through". However, the entire point of his training procedures, operational SOPs and the underlying regulations are to expressly avoid him having to do so.
I do not really accept "Pilot Error" is ever really to blame for air accidents in proffessional crew. There are usually systemic or cultural factors that lead the crew into un favourable conditions and/or behaviours. I know the Commander of this flight very well. He is Pilot held in high regard by all who know and fly with him. It may be that Mixed Mode flight is the prime causal factor in this case. But reading some if the posts on this thread, by some crews, speaks volumes for the training, culture and practices currently deployed in the UK sector. Look inward and embrace change.
DB
Last edited by DOUBLE BOGEY; 6th Sep 2013 at 07:49.