An A320 comms question

[CJ1234]

Folks I am new to this forum. I apologize immensely if this question is too simple - I am not an airline pilot... yet.

If this is the wrong place to put this question, or if it's too simple and/or irrelevant for this forum, please tell me.

However, I would first like to know how one uses the ACP on the A320/330.

Namely, how does the INT/RAD switch work? If one wants to speak to the engineer through the interphone, I don't see why you would need the interphone switch. Surely you would just press the MECH transmission button and then select the MECH reception knob.

What does the INT/RAD button do? How does it work?

Also, when one is forced to shut the port engine on the A319 down (so materials on stand aren't sucked into the engine), what is the procedure for the hydraulics? I have heard you have to turn the YELLOW ELEC pump ON, then OFF after Engine 2 shutdown.

Is this right? Can anyone feed my intrigue?

I'm sorry if these questions are inappropriately simple.

[EMIT]

The RAD/INT switch:
RAD means you transmit through the channel for which the MICrophone button is selected - this can be any radio, the interphone, the Public Address system, etcetera.
Selecting RAD is the same as keying the Push To Talk switch on the hand mike, or on the base of the sidestick.
The RAD/INT switch is springloaded from RAD to the neutral position.

The INT position is a fixed position, meaning, the switch will not jump back to neutral when released. The INT position "transmits" over the interphone (only) so you will have a hot mike for conversation with other cockpit crew and with ground engineer. Using this hot mike, you can leave the MIC button selected for the radio that you use for contact with ATC.

[DesiPilot]

Namely, how does the INT/RAD switch work? If one wants to speak to the engineer through the interphone, I don't see why you would need the interphone switch. Surely you would just press the MECH transmission button and then select the MECH reception knob.

Well, by keeping the switch in INT position it is a hot mike and the mechanic can hear everything that you say on the intercom. Whereas, by keeping it in neutral position and selecting the INT switch, you can decide what mechanic gets to hear.

What does the INT/RAD button do? How does it work?

On INT mode it is a hot mike and works just like a normal intercom, in the middle is neutral position where neither is selected, when RAD is selected it act as a PTT button, the transmission takes place depending on what you have selected on the ACP.

Also, when one is forced to shut the port engine on the A319 down (so materials on stand aren't sucked into the engine), what is the procedure for the hydraulics? I have heard you have to turn the YELLOW ELEC pump ON, then OFF after Engine 2 shutdown.

If you are forced to shut down one engine I am sure you'd have more problems than materials being sucked into the engine!! The normal procedure for engine start is to start #2 first and for shutdown is to shutdown #1 first. That way Yellow HYD system is available and that is what powers the parking brakes. If on the triple indicator the ACCUM pressure is low, you can turn the YELLOW ELEC pump ON but with mechanics consent, incase they are working on something down under.

[CJ1234]

great work fellas - but still a bit confused

I presume you guys are 320 pilots - how would you make a ground call to the engineer (to ask for pushback, for example)? Would you just put the switch into the INT position and talk? how would you do it? (step by step preferably!!)

Any help greatly appreciated from any of you folks

John

[matthewgamm]

@DesiPilot -- I understand that the INT position enables continuous transmission between cockpit crew and mechanic, and between cockpit crew also, without any PTT action. You also mentioned that pilots can decide what the mechanic gets to hear by selecting the NEUTRAL position, and when they wish to communicate with the mechanic, simply select the INT position. I have a question though -- During the time that the switch is in the NEUTRAL position, how do the cockpit crew communicate with each other?

Also, what is the reason for shutting down the number 1 engine first?

Thanks

[KERDUNKER]

Shutting down #1 engine is required on certain stands due the short body of the 319 which means that the engine will be very close to the Jetty, the airfield notes will state the stands which require this action.
Beware #1 engine supplies the green hydraulics which provides normal braking.

#2 routinely shut down on ground to save fuel in some companys

[DesiPilot]

Mathew,

It is a catch 22, if you bring the switch to neutral you cannot talk to each other, leaving on INT mechanics can hear everything. So normally I leave the switch in INT position and whenever I want to speak to FO and want it sensored I bring the switch to neutral and direclty speak to other pilot without any of the electronics.

CJ,

During pushback I keep the switch in INT position and talk to engineer directly without pressing any switch. Alternatively, I have some people keep the INT switch in neutral position, select the intercom TX and use RAD to PTT. I find the later one more cumbersome so during pushback I keep it on INT at all times.

[matthewgamm]

Desi Pilot,

While on ground, during cockpit preparation, with the INT/RAD switch in the NEUTRAL position and use of no electronics, are the cockpit crew members able to hear each other clearly?

What do the selection and rotation of the INT and CAB reception knobs enable?

Thanks

[CJ1234]

i understand now desi


CJ

[EGPFlyer]

While on ground, during cockpit preparation, with the INT/RAD switch in the NEUTRAL position and use of no electronics, are the cockpit crew members able to hear each other clearly?

You are only sitting a couple of feet away from the other chap/chapess so it's not a problem unless you've got your headset on both ears and have something like the ATIS on really loud in the background.

What do the selection and rotation of the INT and CAB reception knobs enable?

the turnable knobs on the ACP enable you to select the source and volume for the headset earphones and speakers.

i.e. during normal ops you'll have VHF1 (ATC), VHF2 (possibly 121.5) and INT selected. If the cabin crew call you then you select ATT (to speak) and CAB(to hear) and turn the volume of any of the other ones down as required so that you can comfortably hear the cabin crew over the other transmissions.

[matthewgamm]

So, as I understand, the rotation of a particular ACP knob controls the volume for the headset phones and speakers. Don't the loudspeakers also have a separate knob for volume control?

To answer an attendant call --- Press the RESET key, select ATT transmission key, release and rotate the CAB reception knob (to be able to hear the attendant) and either use the RAD PTT, sidestick PTT or hand mike PTT keys to talk.
Is it required to select the ATT transmission key?

[Cardinal]

Yes, you would have to select the ATT transmit button on the ACP.

[aerospace.beta]

Hi guys,

saw you guys talking about A320 ACP so thought maybe someone from you will have the knowledge of about the P/N and manufacturer for INT/Rad switch and the Back lit Push button Potentiometer switch.
I am sorry if I am not suppose to post here...........I just need help to find these parts.

Regards,

Sam

[Rick777]

The reason for the INT switch has nothing to do with ground operations. It is for when you are wearing your oxygen mask and can't talk cross cockpit. Also the matter of which engine is started first varies with operator. I almost always started number 1 first because the green hyd system operates the brakes and steering. You don't need the yellow system anyway. Also if you do single engine taxi as I usually did you have to have the green system.

[Slasher]

Rick 777 after landing you can still use the Yellow to 'power' the Green via the PTU if you have to. FCOM says though to shut No 2 down and use the electric pump as the PTU is a fragile piece of French metal.

[Rick777]

Yes you only need either the green or yellow system to power the other one with the PTU. I don't know how fragile the PTU is, but it makes a lot of noise in the back. We would turn it off for single engine taxi in. I had an engine quit one time and noise from the PTU was really disturbing to the passengers. They said they were afraid the plane was coming appart.

[Colin Oskopi]

the common practice

Approaching push back time one has VHF 1 selected to Ground and transmitts through the side stick push to talk button. (We always use this procedure to talk to ATC.)

So nobody get confused we use the INT switch on the ACP to talk to the engineer down stairs. This way you can listen with your other ear to ATC and you are using different hands to talk to different people.

There is nothing worse that asking ATC if "all doors are closed and locked?"

Hope that clears it up.

[AF330]

Good morning,

Sorry for talking back this very old thread...I had some questions related to comms as well.

On this thread, we said that to answer an attendant call --- Press the RESET key, select ATT transmission key, release and rotate the CAB reception knob (to be able to hear the attendant) and either use the RAD PTT, sidestick PTT or hand mike PTT keys to talk.

1. So what is the use of these transmission keys? Do they just enable transmission from the cockpit?

2. Let's say I have tuned VHF1 on RMP1. VHF1 Transmission key is selected on ACP (3 green lights on). I have pulled and rotated the VHF 1 knob on ACP as well. I can now contact ATC using three ways:
- Use the RAD spring loaded switch
- Use the hand mike PTT
- side-stick PTT.

Now, let's say we receive a call from cabin crew. The CALL light turns amber. We press the RESET key and push the ATT Transmission key. We then pull and turn the ATT reception knob. We can now transmit and receive to/from the cabin crew. We can transmit using three ways:
- Rad PTT
- Hand mike PTT
- Side Stick PTT

We notice here that we transmit using same methods. However, when pilots talk to cabin crew, they don't transmit to ATC (hopefully!). So what happens exactly? VHF 1 Transmission key automatically turns OFF to let us transmit to cabin crew?

3) If ground contacts us, MECH turns amber. We reset the switch. We now have two ways to talk to each other:
- INT
- Press the transmission key (VHF 1 transmission key which was selected before turns OFF) + a PTT switch (RAD/Side Stick/Hand mike)
Is this right?

4) I had the chance to get a small ride in the cockpit few months ago (jumpseat). Pilots gave me a headset (connected to RMP/ACP 3) and I could hear both pilots. However, they could not hear me when I would talk. What configuration was this? How do pilots talk between them during flight? They keep the position on INT? So on ground, they keep it on Normal and as soon as ground disconnects, they pass it to INT?

Thanks!

[FlightDetent]

Correct entirely.