A320 Communication Systems: Questions and Answers

This page was one of the Airbus Tech notes, a set of A320 systems study pages. It was written as questions and answers. The original warned that if any information conflicts, the FCOM is the overriding reference, and the same applies here.

Radio management panels (RMPs)

There are two RMPs on the centre pedestal and a third on the overhead panel. Each RMP can control any VHF or HF transceiver. RMP 1 and 2 connect directly to all the VHF and HF transceivers, and RMP 3 connects through RMP 1 and 2. The panels are linked so each shows the selections made on the others.

• RMP 3 can control VHF and HF through RMP 1 and RMP 2 even if those panels are switched off.
• If an RMP loses power and comes back, the last selected frequency stays in the active window.
• The SEL light glows white on both RMPs when a transceiver is tuned by an RMP other than its normal one. These cases are VHF 1 tuned by RMP 2 or 3, VHF 2 tuned by RMP 1 or 3, and VHF 3, HF 1 or HF 2 tuned by RMP 1 or 2. So tuning HF 2 from RMP 1 turns the SEL light on, on both RMPs.

A failed or frozen RMP

When an RMP fails, it no longer controls its receiver, the frequency display goes blank and the green VHF or HF lights go out. Set the affected RMP to off. One RMP can control all the receivers. If RMP 1 fails, tune VHF 1 with RMP 3. If RMP 2 fails, tune VHF 2 with RMP 3. If RMP 3 fails, tune HF 1 with RMP 1 and HF 2 with RMP 2. If two RMPs fail, use the remaining one for everything. If the F/O's RMP fails, he can use RMP 3.

A frozen RMP shows itself when you cannot swap the active and standby frequencies. The fault can come from another RMP, so reset all of them one after the other. Switch each to off, wait 5 seconds, then switch it back on.

Radios and datalink

• VHF 3 is mainly dedicated to ACARS.
• HF transmission is inhibited on the ground. The GND HF DATALINK push button on the overhead panel can override this.
• To hear the DME audio linked with an ILS, the LS push button on the FCU must also be selected.
• The loudspeaker volume knob only sets the level of radio communications. It does not change the loudness of aural alerts and voice messages.

Faults and warnings

If a push to talk switch sticks in the transmit position, the VHF warns after 30 seconds. An interrupted tone sounds for 5 seconds and the transmission is cut off. It works again once the crew releases and presses the PTT again. The ECAM shows VHF 1 (2)(3) EMITTING or HF 1 (2) EMITTING, with a single chime and a master caution. It is inhibited in flight phases 3, 4, 5, 7 and 8.

If CIDS 1+2 FAULT shows on the ECAM after engine start, the flight crew is only being informed. The passenger address, the cabin and service interphone, and the passenger signs do not work.

Audio panels (ACPs)

• If ACP 1 or 2 fails, the crew can use the third ACP with the AUDIO SWITCHING panel. The knob has three positions: NORM, CAPT 3 and F/O 3. This takes the audio equipment away from the third occupant, and AUDIO 3 XFRD shows in green on the ECAM memo.
• A passenger address made with the cockpit handset needs no action on the ACPs.
• The ATT light on the ACP flashes green with a buzzer when a cabin crew member calls. It goes off after 60 seconds if not reset.

Service interphone

A mechanic on the interphone jack during an engine start with the start valve not opening uses the MECH transmission key and the INT knob for reception. The SVCE INT OVRD push button, when on, allows communication even when the landing gear is not compressed, and its ON light is white. The interphone connects the flight crew and the jacks, the flight attendant stations and the jacks, and different jacks to each other. A reader commented that the transmission and reception key for the service interphone should read CAB.

Emergency calls and evacuation

Call from the cabin to the cockpit

The white ON light and the amber CALL light flash, the amber ATT lights flash on the ACPs, and three long buzzers sound in the cockpit. The buzzers are inhibited during takeoff and landing. In the cabin, EMERGENCY CALL shows on the attendant indication panel. The system resets when the attendant hangs up.

Call from the cockpit to the cabin

In the cabin, a pink light flashes on all the area call panels, EMERGENCY CALL shows on all the attendant indication panels, and a high low chime sounds three times on all loudspeakers. In the cockpit the ON light flashes white and the CALL light flashes amber.

Evacuation

If EMER EVAC is started from the cockpit, the EVAC light on the COMMAND push button flashes red and a horn sounds. In the cabin the EVAC lights flash on the forward and aft attendant panels and the evacuation tone sounds. If it is started from the cabin with the CAPT and CAPT/PURS selector at CAPT, only the cockpit horn sounds, for 3 seconds.

Cockpit voice recorder (CVR)

The CVR switches on by itself on the ground during the first 5 minutes after electrical power is on, on the ground with one engine running, and in flight. On the ground the crew can also switch it on with the GND CTL push button. It records the last 2 hours.

To test it, the parking brake must be on. Then:

• Set RCDR GND CTL to on.
• Turn both loudspeaker volume knobs off.
• Set the ACP INT/RAD switch to INT, and release the interphone reception knob and turn it to maximum.
• Press and hold the CVR TEST button. A test tone and a short repeating signal every 4 seconds should come from the loudspeakers.
• Speak into the hand microphone, not the boomset, and check your voice is heard on the loudspeakers. Only then release the button. Some acoustic feedback is normal and does not spoil the test.

Oxygen mask microphone

The oxygen mask microphone turns on when the mask is taken from its stowage. After use, pressing the RESET slide on the stowage box shuts off the oxygen and the mask microphone.

See also the other pages in the Airbus Tech notes.