Five by five

I’m a big Buffy the Vampire Slayer fan, and I’m wondering about a phrase used by one of the characters, Faith, to indicate that everything’s good.

“Five by five,” she says.

What does it mean? Someone I know says it has something to do with aviation. Can anyone enlighten me?

Here is a thread at a site called Phrasefinder that indicates it’s a confirmation of sufficient reception in radio communication.

Yup, signal strength is rated on a scale of one to five and clarity is also rated on a scale of one to five. Five by five is as good as it gets.

Jeez, what’s with this question? It’s been asked like two times in the past month.

Sometimes, a short chubby person is referred to as “five by five,” (feet) but, given the context, I’d go with the radio reception meaning.

what JonF and beatle said.

From this page, Aviation Glossary

5 by 5 : Five by five is an expression used in aviation (and maybe other) radio communication to indicate the quality and loudness of received voice transmissions. Rated one to five indicates - first figure - clearness and - second - loudness. Five by five means that a transmission is received clear and loud (in clear words usually loud and clear is used…). One by one, on the other hand, means it can hardly be heard and is not understandable. If you have a loud but distorted transmission, you may hear two by five, and a weak but clearly understandable one may be called five by three…