It is a pointless exercise trying to ascertain whether this operation was conducted under VFR because, unlike IFR, there is no firm basis for establishing compliance without reference to: the State's regulations; any alleviation/mitigation that applies to CIVSAR; the requirements of the SAR OM; and, the
company safety culture under which the rule set is applied.
That is why in an earlier post, the comment was made that 'culture of SAR in the civil era needs a review'.
It is quite inappropriate to quote other State's operational regulations in this discussion because they are not universally grounded. The ICAO Annex 2 Standard states:
CHAPTER 4. VISUAL FLIGHT RULES
4.3 VFR flights between sunset and sunrise, or such other
period between sunset and sunrise as may be prescribed by the
appropriate ATS authority, shall be operated in accordance
with the conditions prescribed by such authority.
Each State provides basic rules and layers them for types of operation. For example:
§ 91.155 Basic VFR weather minimums.
(1) Helicopter. A helicopter may be operated
clear of clouds if operated at a
speed that allows the pilot adequate
opportunity to see any air traffic or obstruction in time to avoid a collision.
...and the layering:
§ 135.207 VFR: Helicopter surface reference
requirements.
No person may operate a helicopter
under VFR unless that person has visual
surface reference or, at night, visual
surface light reference, sufficient
to safely control the helicopter.
Very few States make a requirement for 'reference to a horizon' or 'minimum visual cue environment' - because it is extremely difficult to 'justify'/'show compliance' with such requirements.
With respect to this accident, it appears that the APBSS chart, in the absence of vertical and visibility limits, is based upon those that apply to CAT - i.e. formerly JAR-OPS and then EASA OPS (as stated in my previous post).
The US regulation does appears to provide a basic (and sensible) objective that should have been met:
However, there has to be a judgement on whether the 'see and avoid' condition applies to the more esoteric 'sense and avoid'. Clearly whilst flight over open seas in the presence of unexpected ships is relatively simple to address, the conditions (
and probable assumptions) under which APBSS was flown, raises doubt.