SAS & DB - You misquote me, I never said that the PM is in charge of the trajectory. I said the PIC is in charge of the whole caboodle and to have the best chance of managing the operation he delegates the flying to the P2. The PF calls the trajectory and the AP modes and the PM (PIC) selects them. He has the brain-space to observe what is happening and veto anything he doesn't like.
With the spectrum of abilities we see on a daily basis, you really don't want the guy on instruments taking his attention away to do the AP selections. Remember that the AP panel is in the middle of the interseat console on the 139.
You may be using your own skills as a reference for the rest of the pilot population. If you read the piece on the end of the link I posted earlier you will see that less than 50% of those we see can be considered to be 'competent'.
G