wrote in message ...

Try 91.205 (d) (2) for starters:

d) Instrument flight rules. For IFR flight, the following instruments and
equipment are required:

(2) Two-way radio communications system and navigational equipment
appropriate to the ground facilities to be used.


That states what equipment is required to be aboard, it does not restrict
the use of equipment not required to be aboard.



Think non-radar operations, where the controller isn't going to play
"Frick and Frack" direct-to games with you. Failure to comply with 91.205
can
rapidly lead to 91.3, and the FAA attorneys win every time.


Nobody suggested IFR operations without the required equipment.