Interesting point, FNG. Speaking up is not always a guarantee that the other pilot will listen!
I was P1 on a non-training cross-water flight with a highly experienced CFI when the weather turned ugly. I elected to return to our departure AD but the CFI, somewhat aggressively, insisted that we continue and effectively assumed control of the flight. We ended up scratching around the oggin at 500’ in 3km visibility and out of radio and nav-aid coverage. The remainder of the flight took place in tense silence, with the CFI refusing to listen to my concerns (which were expressed in a non-confrontational manner). He felt his actions were justified by our eventual safe arrival at the destination AD.
Since then I always address the command issue in the pre-flight briefing,whether I’m flying with an ATPL or SPL. Whilst I welcome advice from any pilot with whom I fly, I insist that I’m the one who makes the decisions—as P1 the safety of the flight is, after all, MY responsibility.
I’d be interested to hear the views of anyone with CRM training on how to deal with this type of situation.