I think part of the explanation for jumping from Herc to Chinook is the description by MoD that an aircraft had gone down. No clarification on helicopter or fixed wing. Once it was established that Hercs were safe, the amount of people missing probably led to conjecture that it was likely to be a Chinook. Not at all helpful to the relatives, and something that the Beeb should not have transmitted. But it also comes down to the initial handling by the MoD. No clarity and hours slipping by.
Like I have said before, I do not think this was handled well by either the MoD or the Media.