Tartare: The picture you portray (taken from the NZAF accident) is a 'rotarians' nightmare and several of us have lost friends in similar circumstances.
Some general points of airmanship relating to such conditions: One of first things to address is a reduction in airspeed the moment you find yourself approaching poor vis when in the proximity of terrain - this buys you time (not much) but time nonetheless. If you are in a formation (or even flying in company) this must be broken, as reduced vis + terrain + formed aircraft, do not mix. The flight would (should) have a break procedure.
Should IMC be entered into inadvertently then climbing away is one potential solution but, as discussed, it is not always possible as the aircraft's performance may be restricted. Moreover, unless trained in the practice of IFR, some pilots quickly become disoriented and which usually leads to disaster within seconds.
So what are some of the 'realities' in circumstances such as these? In reality and unless someone is confident enough to 'climb through' (confident not only in their ability to properly control the craft but also that the craft will be able to reach MSA) they will instinctively attempt to recapture VMC and which usually means one of four things; 1) Pushing on in current conditions while praying for an improvement in the vis, 2) Attempting to back-track (I say attempt because it is in attempting this manoeuvre that many souls have perished), 3) Descending (in the hope of exiting IMC), or 4) A combination of all the aforementioned.
While executing the above responses, many many drivers over the years have caught 'lucky breaks' (including yours truly) but, it is probably the most unpleasant of rotary-wing experiences and - many more have paid the ultimate price for 'finding' (or placing) themselves in such circumstances.
In my own case many moons ago and not too far away from New Zealand, my years of flying in Papua New Guinea brought me closer to heaven gates (or maybe even the other place) than I cared for.
Despite the fact that I had a reputation for 'playing it safe' when it came to weather, in a place like PNG if you only flew when the weather was fair, you simply wouldn't fly. Certainly no meaningful work would get done. As you 'learned' the weather you would develop the parameters within which you could safely work but .. that was very much an individual experience for each driver.
One time we had a newbie driver (ex plank) who inadvertently entered IMC in a 500. He ploughed through till he came out on top (I think at around 21,000 feet .. the MSA in most parts of PNG is usually around 19-20k in anycase).
Somehow (before running out of fuel) he managed to find a hole and eventually landed back at Goroka. He was lucky (as well as a few other things that I won't mention here). I remember the ship's entire strap-pack had to be replaced after his exploit.
May I share what often happens as you get older and gain experience? In a sentence .. you basically learn to steer clear of such scenarios. For me, as the years went by, I simply found myself able to better recognise patterns of weather deterioration and its relation to my environment (mountainous and hilly) and to respect the vice of weather. Low fuel and or fading light would cause me to push back, even further, those 'parameters' within which I had found I was able to safely work. That's the 'experience' bit. The 'getting older' bit (spurred by the loss of friends who had perished in circumstances of poor weather) meant that when a pushy client or demanding ops manager piled on the pressure, you simply dug in your heels with that life-saving word .. no!
I have over the past year asked myself several times whether in the case of AJ Smith, Agusta's new 'synthetic vision' would have given him the ability to 'swerve' the hilltop upon which he met his fate. I don't know. Possibly. Perhaps with reduced speed. Synthetic vision may turn out to be a blessing for cases of inadvertent entrance into IMC or .. it could achieve nothing (or even make things worse) if drivers use it to 'extend' the parameters of VMC.
At the end of the day in every single situation, it comes down to airmanship. Professionalism (if one is flying commercially), common sense (or just good airmanship) if you are flying privately and in both cases .. discipline.
The golden rule in this area is a pretty simple one. If you're flying VFR .. keep it that way!