When can you not be "visual" under the VFR?
A quick question for all you controllers out there. Several times recently, in class "C" terminal airspace, the approach controller has issued instructions to"Turn left/right xxx degrees visual" or "climb to xxxx feet visual" and not been satisfied when my student has not read back the "visual" instruction.
My question is; how can you not carry out the instruction to turn, climb etc. without remaining "visual" if you are flying under the Visual Flight Rules. To become "not visual" would be a breach of the regulations surely.
While I am aware of the necessity for such an instruction for the IFR pilot and the need to obtain their acknowledgement of the instruction, surely it is a redundancy to instruct a Visual Flight Rules pilot to remain "visual".
I would welcome any enlightenment that can be offered in a spirit of enhancing my undertanding; Thanks.