Final answer:
To use RNAV (GPS) for navigation, a GPS receiver must detect signals from at least four satellites with precise atomic clocks. The system must also account for the effects of special and general relativity to maintain accuracy in positioning.
Step-by-step explanation:
To effectively use RNAV (GPS) as the primary means of navigation, a few critical requirements must be met. Firstly, the onboard GPS receiver must be fully functional and capable of detecting signals from the GPS constellation of satellites. A minimum of four satellites must be visible to accurately calculate the position of the aircraft. Each GPS satellite carries a highly precise atomic clock, necessary for determining the time it takes for signals to travel from the satellites to the receiver.
Moreover, it is crucial for the GPS system to factor in the effects of special and general relativity. The high velocity of the satellites and their location above the Earth's surface necessitate adjustments for relativistic time dilation to maintain the high accuracy needed for navigation. Without compensating for these effects, GPS accuracy would degrade rapidly, making reliable navigation impossible.
Therefore, a suitable RNAV (GPS) system relies not only on the proper functioning of the receiver and signal detection but also on the precise synchronization of the satellites' atomic clocks and consideration of relativistic effects to ensure consistent and precise positional data.