What is the actuall function of the R/T and I/C on the ASP? I believe you also have this on the control wheel.

What is the actuall function of the R/T and I/C on the ASP? I believe you also have this on the control wheel.

 

This is discussed some in the 777 Tutorial #1.5.

 

Basically, it switches between the radio and intercom.

...and if you read in to the FCOMs you'll find it's all very confusing, as what audio routes where depends both on what you have selected on the ACP and whether you push R/T or I/C to talk. So there are times where you can/could use the R/T button to, for instance, speak on the interphone to the ground engineer or even on the PA (which is, I would wager, where the occasions when a PA goes out on the ATC frequency arise).

 

I'm just happy I don't have to worry about it in the sim!

This is discussed some in the 777 Tutorial #1.5.

 

Basically, it switches between the radio and intercom.

 

Thanks kyle but still doesn't solve my understanding.

 

 

...and if you read in to the FCOMs you'll find it's all very confusing, as what audio routes where depends both on what you have selected on the ACP and whether you push R/T or I/C to talk. So there are times where you can/could use the R/T button to, for instance, speak on the interphone to the ground engineer or even on the PA (which is, I would wager, where the occasions when a PA goes out on the ATC frequency arise).

 

I'm just happy I don't have to worry about it in the sim!

 

Hi simon hows things?

 

Yeh i've been reading the FCOM and still i don't make much sense of it. So with the I/C you can speak to anyone IE ground, FA etc without selecting the MIC selector switch to FLT or SVC and you can just stay on VHF 1 mic selector?

Thanks kyle but still doesn't solve my understanding.

 

You asked for the function. It switches between the radio and the intercom. I didn't go into any detail because the function really isn't too helpful in the sim. If you wanted more detail you could have been more specific, as the actual details can get pretty complex:

 

The INT (I/C) position allows you to use the flight interphone system as if it's a phone. The mic remains hot in this mode (as if it's a phone). The flight interphone gets you both flight and service interphone systems, provided you select the ON position for the Service Interphone on the overhead.

 

The MIC (R/T) position allows you to use the system in its regular mode of operation. The mic requires the use of the PTT.

 

There are more intricacies to this (the F/D handset as an example), but your best bet there would be to read the FCOM, or head on over to SmartCockpit and have a look at the 777 Communications PDF.

Thanks kyle but still doesn't solve my understanding.

 

The simple answer:

 

R/T - You are talking on the radio.

 

I/C - You are talking to the guy sitting next to you or the guy on the pushback tug if he is plugged in.

Good thank you!

 

To be honest, I don't completely understand it and really you need someone who uses the system day in day out to explain. However, what I think happens is that a destination selected on the ACP is fed using the R/T position -- so if, for instance, the MIC selector is set to PA on the ACP, you would press the R/T button to use the headset boom mic to talk on the PA -- the same if you were to select INT, CABIN etc. If the MIC selector is on, say, VHF1, then the R/T button would transmit on that radio.

 

On the other hand, the I/C switch transmits only on the Interphone. This would usually be the ground crew via the jack in the nose gear wheel well, but certainly on the 747 there is also a SERV INT switch which can connect the Service Interphone system -- which includes ground crew stations at other locations around the aircraft - in to this as well. But if you want to use the boom mic to answer an interphone call from the cabin, for instance, you would have to select CAB on the ACP and use the R/T switch to communicate.

 

I think!

 

Edit: Kyle and Joe got here ahead of me (that's what you get for starting a post, wandering off and coming back to it!)

So the R/T is only used for ATC and I/C for the ground crew and FA etc

Ahh i see simon. So whatever MIC you have selected and if you then press R/T it will transmit on that MIC selector ie VHF1

On the other hand, the I/C switch transmits only on the Interphone. This would usually be the ground crew via the jack in the nose gear wheel well

 

In this day and age more and more pilots are using noise cancelling headsets.  It's become fairly common for the two pilots to talk to each other via the intercom.  Currently the I/C position is spring-loaded so you have to hold it.  On our new deliveries they are putting in a new switch that will latch in the I/C position.  Until then there are various (unapproved) methods guys use to hold the switch in the I/C position.  With the switch in I/C you can still use the PTT switch on the glareshield to talk on the radio.

what about on control wheel that has INT on the top part

Thanks Joe, makes sense. Am I right in my interpretation of how the ACP works -- i.e. the MIC selector determines the destination that will be fed by the R/T switch?

 

If so, I presume the glareshield PTT is also governed by the MIC selector -- or is it exclusively for the VHF radios?

 

Cheers!

R/T - whatever is selected on the ASP

I/C - just the wheel well and pushback, the cockpit and the APU area. No FA.

I have a cockpit video of the 737 NG and during push and start the Capt has the ASP always on VHF1 so is he using I/C to speaking to ground? And I/C overrides the MIC sel ???

I have a cockpit video of the 737 NG and during push and start the Capt has the ASP always on VHF1 so is he using I/C to speaking to ground? And I/C overrides the MIC sel ???

It's a 3-position switch. R/T-Off-I/C.

On MIC SEL you have SVC INT is that used for so everyone can hear you on it from all stations?