Final answer:
The four prohibitions of the RNAV system when a facility is identified as required are: not being able to use GPS as a primary means of navigation, limited access to certain airspace, requiring special permissions, and potential interference with radiation detectors.
Step-by-step explanation:
The RNAV system, which stands for Area Navigation, has certain restrictions or prohibitions when a facility is identified as required. These prohibitions are:
- Not being able to use GPS as a primary means of navigation: When a facility is identified as required, the RNAV system cannot solely rely on GPS for navigation. It must have other means of navigation, such as ground-based navigational aids.
- Limited access to certain airspace: The RNAV system may not have approval to fly in certain types of airspace, such as restricted or prohibited airspace, due to the facility requirement.
- Require special permissions: When a facility is identified as required, the RNAV system may need to obtain special permissions or clearances to operate in certain areas, especially in sensitive or restricted airspace.
- Potential interference with radiation detectors: The RNAV system may set off radiation detectors in airports, which may require special procedures or clearances to pass through airport security.