"Fail to show that you're pilot in command and it will go bad for you. Be the Captain of the aircraft on that flight."
I think I almost failed my PPL skills test when I asked the examiner what they would do in a situation I was presented with. I knew what I wanted to do and did it, but I didn't tell him and just asked to make conversation really... Will remember not to do that again
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When I fly with friends I ask them to limit conversation during critical times such as take off, approach etc.