Originally Posted by rickair7777

An SIC cannot log PIC for these purposes.

But if agreed to in advance, the PIC can allow the SIC to "perform the duties of PIC", and log SIC time with remarks to that effect.

This time is NOT PIC by any means and cannot be logged as such, but it is SIC which you can substitute for the FAA ATP 250 hour PIC requirement.

This is nothing new, it used to be done all the time at mesa since many of their FO's were MAPD with 200 hour COMM AMEL (and not all of that was PIC). They had to do it to upgrade.