I have been operating a BK-117 in an air ambulance capacity in a coastal environment for 19 years. I have to say with the proliferation of awos and asos the current 'snapshot' of current weather is vastly improved over that of 19 years ago and taken together with the 2 stations in our area that offer TAFs a pretty good overall view can be gained. But, weather is neither static nor homogeneous and therein lies the problem. I have gone inadvertent IMC when the lowest ceiling forecast was 2,000 feet and have shot an ILS breaking out at 300 feet when the ceilings were forecast above 1200.
Our minimums here are 600/ 2 1/2 day and 1200 and 3 night and we still have 3-4 inadvertent IMC excursions a year total in our operation. The vast majority happen in level cruise flight and at night. Our normal flight is about 70 nm and a long flight is about twice that one way. Many of our flights are conducted over areas with little or no ground lights.
It is my experience that regardless of minimums, if operations are conducted at night, at least in our area, you will encounter inadvertent IMC. With that in mind I have done the following to reduce the probability of CFIT.
I hired only instrument experienced pilots. Two of us come from a corporate flight background operating a twin engine helicopter in 'heavy' IFR. Even so the vast majority of time it is quicker and more convenient to fly VFR in even the best equipped helicopter so all our pilots also had fixed wing time in aircraft like the Citation 500 and King Air. That is where they got the depth of their instrument time.
My pilots are required to maintain instrument competency and take an annual IPC. There is no limit on the use of our aircraft for instrument training. I prefer the pilots fly double the minimum number of approaches specified by the FAA and I prefer not more than 30 days between approaches. I also try to get each pilot some actual instrument time in our helicopter each year if possible at night. I do everything possible to make this happen when it is convenient to them.
Our aircraft is well equipped with a Garmin 530 and a 496 for weather download capability in flight as well as the usual complement of flight instruments. Current plates and charts are kept on board. We are not an IFR service but, short of an autopilot,we equip our aircraft as if we were.
Finally I back my pilots up. Ours is a pilot run system with the pilot being on the top of the pecking order. Input from each pilot is encouraged and solicited. By job description pilots are only allowed to be assigned "pilot related duties". To give my pilots incentive to train and not become complacent, I make sure they are well paid.