What phrase should an operator use to request a repeat of a message?

The phrase "SAY AGAIN" is the standardized terminology used in aviation communications to request a repeat of a message. It is clear and unambiguous, helping to ensure that both the sender and recipient understand the intention behind the request. Using this phrase minimizes confusion and facilitates effective communication, which is vital in aviation contexts where miscommunication can have serious consequences.

Other phrases might not convey the same clarity or might imply different actions. For example, "REPEAT AFTER ME" suggests that the person should echo back what was just said, instead of simply repeating the entire message verbatim. "MESSAGE REPEAT" is less commonly used and might not be recognized universally in all aviation contexts, potentially leading to misunderstanding. Similarly, "RE-TRANSMIT" could imply a more technical action rather than a simple request for repetition of the previous message. Therefore, "SAY AGAIN" is the most appropriate and widely accepted term in aviation communication for requesting a repeat.