Where the buck stops!
It may come as a surprise to some observers of the offshore oil support aviation industry to find that the relationship between the oil company ( client) and aviation provider is completely different to that which occurs when we fly on a scheduled airline.
Offshore oil operations are chartered flights. i.e. the aviation services provider undertakes to transport people and cargo for the client at the clients request only.
This explains why the clients have ( sometimes) extensive aviation departments providing advisors and auditors to oversee operations conducted on their behalf.
The true test of which party is ultimately responsible will be the courts.In many cases the oil companies ( some of whom are headquartered in the USA) are the final defendents of legal actions brought by injured parties,hence their highly intrusive intervention in the day-to-day operations of their chartered aviation providers.
Given the propensity of US courts to sometimes award substantial monetary payments to victims of offshore helicopter accidents it is no wonder that contracts between aviation providers and oil companies reflect this reality.