Tactical Channel 5

Channel 5 (also known as tac-fiver) was a transmission frequency use by TIE fighter pilots for the Galactic Empire. This frequency allowed pilots to receive transmissions from their squad leaders before a mission commenced. Because it was a low-powered channel with a limited range, it allowed pilots to communicate without enemy interception. It also allowed for pilots to communicate without being overheard by the communications officer on their home chip, as long as the squad was a far enough distance away.

Sources

• The Complete Star Wars Encyclopedia