What is in the pipe five by five?

"In the pipe, five by five" is a phrase used in military radio communication to indicate that the message has been received clearly and without any problems.

The term "in the pipe" refers to the communication channel or pipeline used to transmit the message, and "five by five" is a rating system used to assess the quality of the signal. A signal rated as "five by five" is considered to be loud and clear with no interference or distortion.

The phrase is believed to have originated in the United States military aviation during World War II, where it was used by pilots to confirm that they had a clear radio connection with air traffic control. However, the exact origins of the phrase are uncertain.

Today, the phrase "in the pipe, five by five" has entered popular culture and is often used outside of military contexts to confirm that a message has been received clearly and without issue.