The following is not a comment on the accident - which is the subject of this thread - but a response to the many posts stating how a 'safe' departure 'could have been achieved'.
It is some time since I delved into the ANO but, with respect to commercial operations (not applicable here of course), visibility can be used in most aspects of approach/departure as follows:
Where RVR is not available, RVR values may be derived by converting the reported visibility in accordance with Appendix 1 to JAR-OPS 3.430, sub-paragraph (h).
The approval to apply the reduced minima for a low visibility take-off - i.e. an RVR of less than 400m - requires an approval in accordance with a set of stringent requirements specified in the regulations. These were originally in JAR-OPS but have been transposed to EASA OPS (and they remain virtually the same). Because application of low visibility take-off procedures require that the LVPs be in force, they appear to be available only to aerodromes which can apply such procedures (leaving out such as Den Helder which, I am told, 'cannot' qualify).
Providing AWO approvals for private operations in the UK was always problematical because there was no (specified) criteria by which the approval could be assessed - unless it was in accordance with commercial practices. There was also no structure for reimbursement of costs although Shell Aircraft did manage to have their AWO operations approved.
Applying the intent of such procedures to a private location is impractical, in my view, and any take-off should have been to the VFR limits applicable at the time - maintaining visual contact. A similar situation obtains with performance - whilst
a Cat A procedure could be used at such locations, the notion that it provides any guarantee is not sustainable (unless tailored to the data collected in a site survey).
The operation of complex helicopters in passenger operations (even though they may be private) should demand the highest standard. These should not be the subject of invention of procedures, or adoption of military practices. They deserve better - in fact they deserve the application of the highest standards; if those standards are those for commercial air transport, that then should be the aspiration of the operator - whoever that might be.
Jim