What does a readability rating of 1 indicate?

A readability rating of 1 indicates that the transmission is completely unreadable. In aviation communications, readability ratings are used to assess how clearly a message can be received. A rating of 1 specifically denotes that the transmission has severe interference or is unintelligible, preventing the receiver from making sense of the transmitted information.

This rating is part of a scale that ranges from 1 to 5, with 5 meaning the message is perfectly clear and distinct. Thus, the designation of a rating of 1 highlights a significant communication issue that could lead to misunderstandings or operational safety risks if critical information cannot be accurately conveyed or understood.