What is difficult to understand is how the requrement of FAR 135.207 is met "..at night, visual surface light reference sufficient to safely control the helicopter".
Isn't it true that most loss of control accidents are in part caused by a reduced visual cue environment. Some of the above commenters discuss flight on instruments...at some stage of the flight.
There is a duty of care involved here whether it be by the operator or by the oil company - or is that asking too much.
What part has the regulator to play in the enforcement of existing rules - or the generation of some specifications that have to be agreed and met.