Then the guy sitting right becomes the instructor, regardless of whether or not he has an instructors rating.
I have flown with many a new Captain on Type. This happens due to various reasons, for example Seniority in the Airline, Transitioning or Upgrading from another Fleet etc.
At such a time the New P1 (on Type) could have less than 75hrs on the machine. Although it takes time for any individual to settle and the odd "correction or two" is inevitable, never have I regarded myself as "becoming" the Instructor.
One day when you possibly qualify as an Instructor and bat around the "Circuit" in a US$ 2 Million Twin Turbine trying to get a 200hr CPL rated on type
, then suddenly you will realise what Instruction is really about.
Having performed a number of different flying disciplines in my short career, I guarantee you that to this day Instruction is one of the hardest, least respected and most demanding...
It is how much effort the individual put into their flying that shows..
Well said CDog!