Which of the following is NOT a required component of a radio message initiation?

The choice indicating that flight altitude data is not a required component of a radio message initiation is accurate because the essential elements needed to initiate a communication typically involve identifying the aircraft, the message content, and the appropriate procedural terminologies, such as "OVER," when necessary.

Identification of aircraft is crucial for clarity and safety, ensuring that all parties involved in the communication know which aircraft is transmitting. The inclusion of message content, if applicable, is also vital as it conveys the purpose of the communication. The word "OVER" serves an important role in signaling that the speaker has finished their transmission and is awaiting a response, thus helping to maintain clear communication protocols.

In contrast, while flight altitude data may be relevant in other contexts, especially during operations or when conveying specific information about a flight's status, it is not a standard requirement for initiating a radio message. Therefore, it is understandable why this component is not mandatorily included in the initiation of a radio communication.