For clarity;
In this case the AOC status of each organisation is not in question.
Each company operated the respective aircraft properly in accordance with their respective Ops Manual and AOC obligations.
The aircraft can not hold the insurance the operating entity does, IT is insured but does not hold 'it'.
It can be expected that the insurer will be obliged to honour their liability obligations provided the company operates in accordance with the agreed terms and conditions.
The question is contractual, who do the charterer and passengers look to for relief and what statutory and civil liability does "A" have and accrue when they "pass it on down the line".
In the context of this scenario, the use of "B + C" by "A" to operate the flight can be resolved into several separate or combination of issues, not confined to the following;
1. a separate or subcontract by "A" with "B + C" each on behalf of the charterer?
2. a separate or subcontract with each without the knowledge/approval of the charterer?
3. What is the effect of there being contractually different classes of operation required other than that they are charter? and is it necessary to advise the charterer?
4. was there an intention for '1' above to be so and if so, can they satisfy '3'.
5. Or were the respective aircraft and pilot belonging to "B + C", hired to operate under "A's" AOC, if so what documentation and approvals are required to legally effect this.
It goes on, I am imterested to hear what the understanding is out there, of this fundamental problem. There are only a couple of landmines here but you only have to step on one.