Happened to me years ago! Was in the right seat with the "chief pilot" taking the aircraft from Tennant Creek to Alice Springs. At night, commenced descent and cleared a visual approach. Weather was perfect.
Old mate just starts trucking down, tracking straight for the airport.
Only trouble........ there is a nice mountain range between us and the airport!
We had the DME arrival plates out, I questioned his profile. His response was "It is ok, we are visual".
My response: "We might be visual, but if you continue that profile you are going to kill us both, what about the mountain range?"
Suffice to say we leveled off and resumed the DME arrival on steps.