Hy .I thought there must be some convention between the CAA and some company which will allow a FOI to fly on on that comp planes,as PF.This is the case where I fly,and the FOI fly with us,few flights monthly to keep their proficiency.
I don't see why they give you dificulties in mantaining your proficiency.We are talking about just a few fights monthly I guess.
There may be some problem regarding the insurrance of that flight when having a non company man at controls,I guess.
We almost had a problem while a FOI was PF,once,and since then the FOI's where not allowed to fly for a while with us,but I think all we'll come back to normal.They are also pilots,and also need training.You must keep in mind ,though,that they fly fewer flights than the rest of the pilots,so maybe some special rostering for their flights.
As I said,all specified in a convention between the CAA and company
Brgds,
Alex