Roy,

2) Split operation (allows one pilot to use one radio while the other
pilot uses a different radio). The pilot flying can continue to talk to
ATC, while the PNF can get the ATIS, talk to flight service, etc,
without distracting the PF.


For that, in my experience, it is quite important to have the com antennas
on different side of the aircraft - one on top, one on the bottom.
Otherwise, you'll likely have bleed-over.

--
Thomas Borchert (EDDH)