The Interphone-radio Control System (ICS) (Figure 1-10-2), amplifies interphone and received radio signals and provides control for: ICS isolation between crewmember and pilots; crew transmissions on UHF, HF, VHF/AM, VHF/FM, sonar and relay of sonobuoy information; and individual reception of radio, sonar and sonobuoy signals.

The ICS system is operative when the No.1 RADIO MASTER switch is in the ON position. The system operates on direct current from the essential bus and is protected by a circuit-breaker marked “RADIO BUS NO.1”, located on the overhead circuitbreaker panel, and by a circuit-breaker marked “ICS”, located on the radio circuit-breaker panel (Figures 1-5-5 and 1-5-6).