CNS System Operation

• The Communication/Navigation/Surveillance (CNS) system incorporates the audio panel, communication radios, navigation radios, and a Mode S transponder

CNS Operation

• The CNS operates via Line Replaceable Units (LRUs)
• LRUs Include:
• Primary Flight Display (PFD)
• Multi Function Display (MFD)
• Integrated Avionics Units (2)
• Audio Panel
• Mode S Transponder
• Control Unit
• MFD/PFD controls tune communication transceivers and navigation radios
• The audio panel offers standard audio selection for microphone and receiver
• The Audio Panel also includes an intercom system (ICS) for pilot, copilot, and passengers, along with a marker beacon system and COM clearance recorder
• Master Avionics Squelch (MASQ) reduces ambient noise from aircraft radios; MASQ processing further reduces background noise when no audio is detected
• Softkeys and the FMS Knob on the PFD control the Mode S transponder
• The transponder data box, located left of the System Time Box, displays the active four-digit code, mode, and reply status

PFD Controls

• COM frequency box shows active and standby frequencies and volume
• The selected COM transceiver frequency is displayed in green
• COM Knob tunes standby frequencies using a large knob for MHz and a smaller knob for kHz
• A press moves the selected digit for tuning and facilitates frequency transfer between COM1 and COM2
• The COM Frequency Transfer Key transfers standby to active COM frequencies; press and hold for two seconds to automatically set the emergency frequency (121.500 MHz)
• The COM VOL/SQ knob controls the COM audio volume level and toggles COM automatic squelch on/off; volume level is shown in the COM frequency field
• The DME Tuning Window displays the DME frequency pairing mode, accessible via the DME softkey
• The ENT key validates DME pairing mode and auto-tune selection
• The FMS Knob enters transponder codes and auto-tune entries (when the NRST Window is present); press to toggle selection cursor, use large knob for cursor movement, and small knob to select characters
• The Transponder Data Box shows the selected code, mode, reply, and ident status
• The NAV VOL/ID Knob controls NAV audio volume and toggles Morse code audio; volume is shown in the NAV frequency field
• The NAV Frequency Transfer Key transfers standby and active NAV frequencies
• The NAV Knob tunes frequencies for the NAV receiver (large knob for MHz, small for kHz). Pressing moves the tuning box and Frequency Transfer Arrow between NAV1 and NAV2
• The NAV Frequency Box shows NAV standby and active frequencies, volume, station ID; the selected frequency is displayed in green

Audio Panel Controls (GMA 350/350c)

• When a key is selected, its triangular annunciator lights up
• Features:
• MKR/MUTE selects marker beacon receiver audio, mutes current beacon, and stops recorded COM audio; it deactivates/reactivates automatically to be heard on next beacon signal
• COM1/COM2 enables hearing audio from the respective COM receiver
• NAV1/NAV2 enables hearing audio from the respective NAV receiver
• Aux enables/disables audio from entertainment/telephone device connected to Front Panel Jack; press and hold to mute/unmute during reception
• MUS 1/MUS 2 selects/deselects music entertainment audio; Hold to enable/disable muting during reception
• MAN SQ indicates Manual Squelch; when lit, intercom squelch is manually operated
• Volume Indicator shows volume/squelch level
• Front Panel Jack is used for entertainment or telephone input
• MIC1/MIC2 selects transmitter 1 or 2 for transmitting; receive is activated when selected; pressing both initiates Split-COM mode
• PLAY plays the latest recorded memory block; press again to revert to previous blocks
• AUX toggles audio from ADF/DME
• PILOT enables pilot intercom isolation
• COPLT controls copilot intercom; hold to toggle copilot configuration between crew and passenger
• PASS controls passenger intercom; hold to enable/disable muting
• SPKR selects/deselects cabin speaker; hold for 2 seconds for Passenger Address (PA), indicated by flashing SPKR
• Cursor (CRSR) Control Knob moves cursor to the desired source
• Volume (VOL) Control Knob controls volume/squelch of selected source; can be switched to Blue-Select mode
• Bluetooth Connection Annunciator (GMA 350c only): Flashing blue indicates discoverable mode, solid blue indicates active connection
• Key Annunicator (GMA 350c only): Assigns the devices bluetooth audio to the sources
• Control Knob (GMA 350c only): Press and hold for 2 seconds to enable GMA 350c discovery for pairing; remains discoverable for 90 seconds or until paired
• Control Knob (GMA 350c only): Press and hold for 2 seconds to enable GMA 350c discovery for pairing; remains discoverable for 90 seconds or until paired
• MUS1/MUS2 Key Annunciator (GMA 350c only): Assigns the Bluetooth device to the MUS1/MUS2 audio source; cycles between OFF, WHITE (wired audio), and BLUE (Bluetooth audio); Bluetooth audio can only be assigned to one source at a time