Final answer:
A pilot-in-command may file an IFR flight itinerary, instead of an IFR flight plan, in scenarios where comunication facilities are inadequate or when the flight takes place partially or wholly outside controlled airspace. Acknowledgement of receipt of a flight plan or itinerary is not a determining factor.
Step-by-step explanation:
A pilot-in-command may file an IFR flight itinerary instead of an IFR flight plan under certain conditions. These conditions include when facilities are inadequate to permit the communication of flight plan information to an ATC unit, an FSS (Flight Service Station), or a CARS (Community Aerodrome Radio Station), which is answer option (d). Situations may arise where communication capabilities are limited or nonexistent, especially in remote areas or due to technical issues. In these cases, a flight itinerary serves as an alternative to the traditional flight plan, allowing a pilot to still convey their intended route and details of the flight.
It is important to note that while flying in controlled airspace generally requires a filed IFR flight plan, filing an IFR flight itinerary may be acceptable when parts of the flight occur outside controlled airspace, which is stated in option (b). Moreover, an acknowledgement of receipt for the flight plan or itinerary is not a condition for choosing to file an IFR flight itinerary over a flight plan; therefore, option (c) is not correct as per the original question's context.
Thus, the correct answers to when a pilot-in-command may file an IFR flight itinerary instead of an IFR flight plan are:
- When the flight is conducted, in part or in whole, outside controlled airspace (b).
- When facilities are inadequate to permit the communication of flight plan information to an ATC unit, an FSS, or a CARS (d).