For systems that operate the required flight instruments which are
located at each pilot's station, the following apply:
(a) Only the required flight instruments for the first pilot may be
connected to that operating system.
(b) The equipment, systems, and installations must be designed so that
one display of the information essential to the safety of flight which is
provided by the flight instruments remains available to a pilot, without
additional crewmember action, after any single failure or combination of
failures that are not shown to be extremely improbable.
(c) Additional instruments, systems, or equipment may not be connected
to the operating system for a second pilot unless provisions are made to
ensure the continued normal functioning of the required flight instruments
in the event of any malfunction of the additional instruments, systems, or
equipment which is not shown to be extremely improbable.