Originally Posted by
Lost in Saigon 
I assume the un-named male First Officer was the Pilot Flying during the descent and initial approach, while Captain Tammie Jo Shults ran the checklist and the radio. (except when the FO responded to ATC clearing SWA1380 direct to Philadelphia)
On final, when they switched to the tower frequency, Captain Shults took over flying while the First Officer worked the radio.
(after landing the Captain went on the radio again)
Originally Posted by
JPJP
Other way around - The PF would be working the radios, and the FO would be running the checklist. If the FO answered a radio call it may indicate that the CA was communicating with the FAs or making a PA. On approach the roles may return to normal, with the majority of checklists complete.
Obviously, it’s the CA perogative if she wants to run the checklist/manage.
To circle back to the answer to this question; from the investigation -
“The captain took over flying duties and the first officer began running emergency checklists. The captain requested a diversion from the air traffic controller;”