ACP 131/ACP 131 US SUPP-1 addresses which type of signals?

• A. Operating Signals
• B. Encryption Procedures
• C. Message Routing
• D. Station Signals

Answer: (A)

The focus here is on the set of standard cues and phrases operators use to control and conduct a radio transmission. ACP 131 and its US Supplement define these operating signals—the procedural language that keeps conversations orderly, signals when to speak or listen, requests repeats, and confirms understanding so transmissions flow smoothly.

This area is distinct from encryption procedures, which are about securing messages, or from routing concepts that deal with how messages travel through networks, or from station signals that identify or locate equipment. By codifying the everyday signals used during operation, ACP 131 provides a common framework for clear, coordinated communication. That’s why operating signals is the best fit.