The A320 communication system provides voice and data communication between flight crew, cabin crew, ground personnel, and external parties via radios. Understanding RMP operation, audio control panels, interphone systems, and cabin calls is essential for effective crew coordination and safe flight operations.
Communication System Overview
The communication system includes VHF/HF transceivers, radio tuning panels (RMP), audio integrating units (AMU), audio control panels (ACP), interphone systems, and cabin call systems. These components work together to provide comprehensive internal and external communication capability.
📻 Radio Systems
2 VHF standard (VHF3 optional), 2 HF, SATCOM, ACARS datalink
🎛️ Radio Management
3 RMPs for tuning, SEL light indicates cross-side control
🎧 Audio Control
AMU integrates audio, ACPs allow TX/RX selection and volume
📞 Interphone
Flight interphone, service interphone, cabin calls, PA system
VHF Communication Systems
The A320 has two VHF communication systems as standard (VHF3 is optional). These are the primary means of air-to-ground communication during flight.
VHF Configuration
- VHF1: Always available, remains powered in emergency electrical configuration
- VHF2: Standard installation
- VHF3: Optional third VHF system
🚨 Emergency Configuration
In emergency electrical configuration, only VHF1 remains available. RMP1 continues to function and can tune VHF1 even when only the emergency electrical network is active. This ensures minimum communication capability during electrical emergencies.
Radio Management Panels (RMP)
Three RMPs allow crew to select and tune communication and navigation radios. RMPs provide cross-side control capability.
RMP Functions
- Frequency Selection: Outer knob for whole units, inner knob for decimals on STBY window
- Transfer Key: Swaps active and standby frequencies
- NAV Pushbutton: Enables tuning navigation receivers and courses
- SEL Light (Amber): Indicates radio normally belonging to one RMP is being tuned from another RMP
🔧 RMP Operation
To tune a frequency: Use outer knob to adjust whole units, inner knob for decimals on STBY window. Press transfer key to swap active and standby frequencies. When SEL light is amber, that radio is being controlled from another RMP (cross-side control active).
Audio Management System
Audio Management Unit (AMU)
The AMU integrates, distributes, and manages all audio signals for radios, interphones, call systems, and passenger address functions. It ensures proper routing of audio throughout the aircraft.
Audio Control Panels (ACP)
Each crew member has an ACP allowing selection of transmission channels, enabling/disabling receptions, and adjusting volume for various audio sources.
ACP Functions
- Reception Knobs: Press and pull out to select for listening, rotate to adjust volume
- VOICE Filter Key: Inhibits navigation ident tones (VOR/ADF) to reduce background noise
- Loudspeaker Volume: Clockwise increases radio communication audio on loudspeaker (doesn't affect aural alerts)
- AUDIO SWITCHING Selector: Connects crew audio equipment to different ACPs (e.g., CAPT 3 connects captain to ACP3)
- Flashing SELCAL Light: Ground station has called aircraft using SELCAL code, aural alert active until reset
Interphone Systems
Flight Interphone
Enables communication between flight crew using boomsets, hand microphones, and oxygen mask microphones connected through the AMU.
- External FLT INT Jack: Located on nose landing gear external panel, allows ground crew to talk with cockpit
- To Use: Pull INT reception knob out, select INT transmission key, use push-to-talk or INT/RAD switch to speak
Service Interphone
Communication between flight crew, cabin attendants, and service interphone jacks installed around the aircraft.
🔧 Service Interphone Logic
After landing, service interphone becomes available approximately 10 seconds after touchdown when landing gear is locked down. The SVCE INT OVRD pushbutton allows ground personnel to use service interphone jacks even if landing gear is not locked down.
Cabin Call Systems
Cockpit Call Indications on ACP
- Flashing ATT Light: Cabin station calling cockpit (normal or emergency call), buzzer sounds unless inhibited
- Flashing MECH Light: Ground mechanics calling from external power panel using COCKPIT CALL pushbutton
Cabin Transmission from Cockpit
- CAB Key: Places selected microphone in transmission mode on cabin interphone
Calls Panel
- ATTND ADV Pushbutton: ON light comes on, green light appears on attendant area call panel (informs cabin crew of imminent takeoff/landing)
- Normal Captain Call: Two steady pink lights on relevant area call panel, "CAPTAIN CALL" on AIP, high-low chime
- EMER Pushbutton: Pink lights flash on all area call panels, "EMERGENCY CALL" on AIPs, high-low chime repeated three times
- Call Reset: When cabin crewmember replaces handset on cradle
Cockpit MECH Call
Press and hold MECH pushbutton: COCKPIT CALL blue light illuminates on external power panel, external horn sounds to attract ground personnel. Ground crew press RESET pushbutton on external power panel to extinguish light and silence horn.
Passenger Address (PA) System
PA function hosted in CIDS (Cabin Intercommunication Data System), which distributes announcements from cockpit and cabin stations to passenger loudspeakers throughout cabin.
Making PA from Cockpit
- Pull PA reception knob out
- Press and hold PA transmission key while speaking into boom microphone
PA Indications
- PA IN USE: PA system active
- IFE IN USE: In-flight entertainment system active
- VIDEO IN USE: Video system active
Cabin Intercommunication Data System (CIDS)
Transmits, processes, and controls signals for cabin and service interphones, PA, lighted signs, lighting, smoke detection, and other cabin functions. Essential for integrated cabin management.