What is required of an aircraft to use GPS effectively during IFR conditions?

For an aircraft to utilize GPS effectively during IFR (Instrument Flight Rules) conditions, it is essential to have alternate avionics for ground facilities. This ensures that in the event of a GPS failure or signal loss, the aircraft can still navigate safely and reliably using other systems, such as VOR or ILS. IFR operations require a high level of navigation accuracy and redundancy, as pilots may be flying in low visibility conditions where reliance solely on GPS could pose safety risks if the system becomes inoperative.

The other choices do not provide the necessary backup or flexibility required for IFR navigation. Relying solely on WAAS capabilities might limit navigation options under certain conditions. Following VOR navigation rules would not incorporate GPS effectively into the flight plan. Being equipped with ILS only would not support necessary navigation throughout an entire flight, particularly on routes where ILS is unavailable. Thus, having alternate avionics for ground facilities is crucial for maintaining safe and effective navigation throughout IFR operations.