Investigation Report of the Dutch Safety Board (in Dutch language)
Summary in Vertical Magazine (English language)
This operation had all going for it: First world, new twin hardware, a crew trained to military standards, which as we read on these pages is far more advanced and not at all comparable to the training standards in the civilian or corporate world.
Yet everything goes wrong:
- The guys are training ship landings, yet no instructor on board - Rather have 3 non-pilot crew on board (Tactical Coordinator, Sensor-Operator, Hoist-Operator)
- Airspeed indicator completely ignored - first thing you are normally taught at PPL level is: "Airspeed, Airspeed, Airspeed".
- What do you do when you run out of power in OGE hover: Pull more collective? What about push cyclic forward to go gain translational lift? What about turning into wind? No, rather wait 11 seconds for the inevitable to happen.
...
Actually, the FDR shows that the pilot did not change anything for 11 seconds despite low AGL and - for the last 6 seconds - 1,300 ft/s sink rate. The mishap pilot only yanked up the collective the moment of the impact with the water.
The report confirms that the NH90 had sufficient power to do a OGE hover at the given conditions - Pilot could have just added power in line with reducing airspeed - Normal procedure for a manoeuvre called "landing", and you learn this before you get sent solo.
- Crew didn't have dunker training. They were not even trained in the proper use of the life vests. Instead, the front seat passenger probably deliberately inflated the vest
inside the cockpit got trapped and drowned.
- The pilot egressed but got entangled "
in a connecting line to the helicopter" and equally drowned. The story about that line is a bit cryptic (well, call it Dutch), but it seems to be a cable between an inflatable dinghy and the pilot suit. And the pilot sits on the dinghy. Anyway, maybe somebody else can shed some light onto this...
- The rescue services emanating from the military vessel the NH90 was trying to land on 'did their best' but also were found lacking in terms of recency training, skills, resources and coordination. For example, they had no rescue divers on board.
The mishap pilot (it was single pilot ops) had 1700 HRS TTRW, and 700 HRS on type in the NH90 (although half of it in the simulator, if I read correctly). So not exactly green neither.
So what happened? They did 7 successful ship-landings already during the same flight. On this 8th one, they wanted to get in photos of the 'foredeck' (I am not a boats person, that's what Google Translate calls it). And as we all know (at least all of us Robbie pilots - refer to Robinson Safety Notice 34 - "Photo Flights - very high risk"), that's when the pilots gets carried away and $hit happens. Of course - as we also read on these pages - this is due to a design flaw of the Robinson product, how else could it be that only the Robinson product carries such warnings 
.