Communications

Table of Contents:
  • Normal Operations
  • Alternate Operations
  • Controls and Indicators
  • Schematics
  • Supplementary Information


Normal Operations


To Establish VHF Communications:

Radio Master Switches:    On
Note: When normal power sources are not available, VHF communications may be established using VHF #1 and standby power.
VHF Mode Selectors:        Normal
Frequency Selectors:         Set
Transfer Switch:                  Desired frequency
Frequency Transfer Light:  Illuminated
Transmit Switch:                 Push
Receive Switch:                  Push the switch in to receive.  Rotate clockwise to increase volume.
Push-to-Talk Switch:          Push


To Establish HF Communications:

Radio Master Switches:    On

HF Mode Switch:                USB, LSB or AM
Frequency Selectors:         Set
Transmit Switch:                 Push
Receive Switch:                  Adjust.  Push the switch in to receive.  Rotate clockwise to increase volume.
RF Sens Switch:                 Adjust.  Rotate the switch clockwise to increase the volume.
Push-to-Talk Switch:          Push

Note:  In case of apparent failure of both HF communication systems, turn off HF No. 2 and attempt communications on HK No. 1. (or vice versa).





Alternate Operations

Radio Transmit Continuous (Stuck Microphone Switch)

A radio is continuously transmitting without crew input.
Interphone Transmit Switch (all audio panels):        Push
Deselects radios and stops radio transmission.
The microphone/interphone with the stuck switch continuously transmits on flight interphone.
The associated audio select panel should remain on flight interphone.
All other audio select panels may be used normally.


Controls and Indicators


VHF/HF/SELCAL Communications


Frequency Indicator:  Displays frequency from 118.00 to 135.95 MHz as set by the frequency selector.

Frequency Transfer Switch:  Permits selection of active/standby frequency.


Frequen
cy Selector:  Rotation of selector changes displayed frequency.




Frequency Indicator:  Range from 2 to 30 MHz.

Mode Switch:

USB - Upper side band.  Extra Long Range.  Station being worked must also have USB.
LSB - Lower side band
AM - Amplitude modulation
DATA / CW:  Provisions only.



Audio Sector Panel


Transmit Switch:  Press in to select transmitter; depressed switch will illuminate.  Only one.

Receive Switch:  Press in to monitor receiver , push again to release.  Switch illuminates.  Any number of receivers may be monitored at the same time.

Norm/Alt Switch:  Selects isolation amplifier in audio selector panel.  Loss of the amplifier selected will cause that audio selector panel only to lose audio.  Switch to alternate.


ADF Filter Switches:
Voice - Range signals are filtered out when selected.  Allows only voice to be heard.
Range - Voice is filtered out when selected.  Allows only range signals to be heard.
Boom / Mask Switch:
                Boom - Select when using boom microphone
                Mask - Select when using oxygen mask microphone
PTT - Installed on later airplanes, same function as control wheel PTT.
Voice Only:  Press to filter out CW signals.




Inputs:





Control wheel PTT switch
- MIC keys light transmit switch
- INT allows pilot to talk over interphone without pressing INT transmit switch.












Oxyen mask microphone or Boom microphone












Hand microphone










Outputs:

Cockpit loudspeaker
Headset



Flight Interphone


Flight / Ground Crew Call System:


On Nose Gear


Flight Interphone Jack.

Grd Crew Call Switch:  When pressed the horn in the nose wheel will sound.

Flt Deck Call Switch:  When pressed a chime will sound in the cockpit and the ON portion of the GRD CREW CALL switch on the pilot's overhead panel will illuminate and remain illuminated for 30 seconds.




Flt Deck Call Switch: 
When pressed a chime will sound in the cockpit and the ON portion of the GRD CREW CALL switch on the
pilot's overhead panel will illuminate and remain illuminated for 30 seconds.


Cargo Interphone:

Call Switches
Handset Switches


Passenger Address:





Service Interphone, Connecting Interphone Systems


Voice Recorder


Erase switch: 
Press for several seconds to erase all four channels.  Airplane must be on the ground with parking brake set and Essential Radio Bus powered.

Microphone: 
Picks up cockpit area conversation on one channel.  Captain's, First Officer's and Flight Engineer's microphone inputs are recorded on three other channels.

Test switch:
When pressed needles on the indicator will deflect to green band and intermittent test tone will be heard with headset plugged in headset jack.

Indicator: 
Fluctuates in green band when test switch is pressed if all four channels are operating.

Headset jack
Headset may be plugged into jack to monitor playback voice audio or tone transmission during test.

Note - Older airplanes:  The voice recorder operates when the ESSENTIAL RADIO MASTER switch is on and the Flight Recorder (AIDS) is on and/or any start lever is out of cutoff position. The voice recorder runs through a complete cycle approximately every 30 minutes.  It then begins a new cycle - erasing the old recording and recording the new.

Note -
Newer airplanes:  With the ESSENTIAL RADIO BUS powered, the voice recorder runs through a complete cycle approximately every 30 minutes.  It then begins a new cycle - erasing the old recording and recording the new.




Schematics

Interphone and Passenger Address System


Interphone System - Cargo



Supplementary Information




VHF Communications:

There are three complete VHF communication systems, each with a separate antenna. 
When the satellite communications (SATCOM) system is installed, two of these units may be connected to the SATCOM system,





HF Communications
:


There are two complete HF commication systems, each with a separate antenna.

Each unit is capable of single side band and amplitude modulation operation.

Both systems may be keyed simultaneously.






Audio Selector Panel:


Serves as a selector for internal or external transmission and reception at each cockpit position.



   

Flight Engineer's Communication Panel  (Lower left of FE panel)



Interphones:


There are three interphone systems:  Flight, Service and Cabin.  Flight interphone may be connected to Service and/or Cabin.  However Service interphone, by itself cannot connect to Cabin.

Flight Interphone:  For cockpit stations exclusive intercommunication.  An additional station (nose gear) is on this circuit for control of ground crew.


Service Interphone:  This system provides for communication between all external service jack and if the FLT/SERV switch is ON, between service and flight stations.

Cabin Interphone:  This system allows telephone-type communication between cockpit (with handset) and passenger cabin attendant stations, between separate attendant stations, and provides the primary means for making passenger announcements.  In addition, the system may be connected to the flight interphone system permitting cockpit to passenger cabin (with boom or oxygen mask mike) communication.


Cargo Interphone:  Provides communication between cargo stations, flight and service interphones.  The Handset switch at the loadmaster's station must be set to Interphone for interphone communications.  With the handset switch to Interphone the loadmaster's handset is connected to the flight interphone system.  Placing the FLT/SERV switch to ON will permit communication by the loadmaster to all flight and service interphone stations.


Cargo Intercom:  Provides speaker/microphone intercommunications throughout the main deck and lower lobe carge areas for hands-off use.  Intercom transmissions from the loadmaster's panel may be initiated by the speaker/mic and PTT switch or by the handset with the Handset switch in the Intercom position.



General:


2 Antennas are located on top and 1 on the belly .... the top positions allow the aircraft to maintain communications in the event of ditching !




Centre consul style



First Officer's Side style with Quick Donning Oxygen Mask abov





Further reading on frequencies:

HF - High Frequency - 3 to 30 MHz: http://en.wikipedia.org/wiki/High_frequency
VHF - Very High Frequency - 30 to 300 MHz: http://en.wikipedia.org/wiki/Vhf:
UHF - Ultra High Frequency - 300 MHz to 3 GHz: http://en.wikipedia.org/wiki/Ultra_high_frequency

Subpages (2): ACARS SELCAL
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