On 737 on the ground the philosophy is Captain and First Officer probably due to the fact the tiller is only available on the captain's side (customer option to have it on both sides), in flight it's PF and PM.
Originally Posted by
gearlever
PF/PM may sound obvious.
Task sharing isn't.
For example in my outfit PF doesn't do the radio calls, in other outfits he/she does.
Usually during abnormals, the PM carries out the NNC and the PF takes over radio communication. At least this is so at my outfit.