What are the four key components that should be included in initial radio contact with an aircraft?

In initial radio contact with an aircraft, the four key components that should be included are aircraft identification, the ATC unit being contacted, the message being conveyed, and the word "over."

The inclusion of aircraft identification is crucial because it informs the ATC unit which aircraft is making the communication. Identifying the ATC unit provides clarity on who is being addressed, ensuring the message is directed appropriately. The message itself comprises the information or request that the pilot wishes to communicate, and using the word "over" indicates that the transmission is complete and awaits a response, clarifying the communication flow between the pilot and ATC.

While the other options list important elements, they do not encompass the correct protocol for initial contact. For instance, including airspeed or next waypoint, while useful in other contexts, is not standard procedure for the initial contact. The acknowledgment is typically part of the exchange that follows the message but isn't necessary in the initial contact statement itself. Thus, option B correctly captures the essential components needed for effective communication during initial contact with an aircraft.