Index
Communications
There are internal communications with inter-phone and PA systems, ground communications via the Service Inter-phone, and external communications via the VHF and HF radios.
Additionally, there is ACARS and SELCAL systems installed for communication with ground stations.
There are several places for the various communication systems. The controls and indications include:
- Radio Tuning Panels on centre pedestal
- Audio Control Panels
- Call system panel
- ACARS
- Cockpit voice recorder
There are PTTs on the control wheels, the ACP, the Glare shield MIC switch, and the hand microphones.
Every radio can be controlled via each radio tuning panel.
VHF radios
There are three independent VHF radios. They are connected to LRU1 and LRU2, respectively, while the third VHF radio is solely for ACARS. There are 3 VHF antennas, two located on the lower fuselage, while the third is on the upper fusealge.
Each radio panel has an Offside Tuning light which illuminates when the radio normally associated with this panel is being tuned any another radio not normally associated with it. The panels also include a “TEST” button that can be used to switch automatic gain control, as well as an AM mode that also sets Upper Side Band mode for the selected HF radio
HF Radio
The B737 has a single HF communication antenna, located on the leading edge of the vertical stabiliser. When tuning an HF frequency, a tone will be heard for a maximum of 7 seconds. Should the system fail to tune the tone will last 7 to 15 seconds.
Audio Control Panel
Each individual headset volume and general speaker volume is controlled by the receiver switches on the ACP.
Additionally, altitude alert, GPWS, TCAS, and windshear alerts are all heard through both speaker and headsets at a preset volume. These cannot be controlled or turned off.
There is an ACP for CA, FO, and observer station. Each ACP controls an independent crew station audio system and allows the crew member to select the desired radios, nav aids, inter phones, and PA system for monitoring and transmission.
Each panel has:
- MIC SELECTOR switches
- Used to select one radio or system for transmission
- Receiver switches
- Can be rotated to adjust volume or to allow any combination of systems to be monitored.
- SELCAL lights that illuminate on the appropriate radio
- A PTT which has both a RADIO position and an INT (interphone) position, which keys either oxygen mask or boom mic
- Ground Crew Light
- Cabin Call Light
- ALT-NORM switch
- Filter switch:
- V - only voice transmission can be heard
- R - only station identifiers can be heard
- B - both can be heard simultaneously
ALT Audio Operation
Audio systems can be switched to a degraded mode by placing the ALT-NORM switch to ALT.
In this mode, the ACP at that station is inoperative and the crewmember can only communicate on one radio. Additionally, receiver switches are not functional and the radio can only be heard through the headset at a preset volume - much like the EMER switch on the Saab 340 ACP.
On ALT mode, each position is bound as follows: CA - VHF1 FO - VHF2 Observer - VHF1
Other items are also unavailable in ALT mode:
- Handheld mic
- APA
- GPWS
- Windshear
- PA system via ACP
ACARS
ACARS reports will usually include performance data, flight status and position reports, out, off, on, in times, and maintenance items.
The ACARS management unit is installed in the E&E compartment. The ACARS MU receives uplink data and controls the transmission of downlink data to and from the VHF transciever. It can be accessed via either CDU.
The “menu” key on the CDU allows access to the ACARS system. From the “MENU” page you can access the FMC, ACARS, or DFDAU (Digital Flight Data Acquisition Unit).
To make the system active on the CDU, push the LSK adjacent to the system prompt (DLK). If ACARS is in control of the CDU, the MSG annunciation comes on when the CDU receives a message, which is shown on the scratch pad (bottom left of CDU).
CPDLC
Controlled-Pilot Data Link Communications is a means of communication between ATC and pilots. The following can be accessed from the ATC INDEX menu:
- Emergency report
- ATC request
- ATC report
- When can we expect
- Verify report
The ATC LOGON/STATUS and ATC LOG prompts allow initiating an ATC connection and viewing stored messages, respectively.
When an ATC message is received, the following indications are shown:
- EICAS ATC message displays
- ATC message on CDU
- Audible hi/lo chime
Flight interphone
The interphone system is designed to provide private comms between flight deck crew members without intrusion from the service interphone system. This system can also be used by ground crew using a jack at the external power receptacle.
There are two methods to use the interphone:
- Selecting the INT on the ACP
- Pressing INT on the control wheel PTT
To initiate a call to ground crew press the GRD CALL switch. This sounds a horn in the nose wheel alerting ground personnel that you are calling. Likewise, on the external power jack ground crew can call the flight deck by pressing a PILOT CALL button, which illuminates the INT light on the ACP and chimes a high tone.
Cabin interphone System
This system allows communication between CCMs and the flight deck, or between various CCM stations. The system includes:
- Two cabin attendant handsets
- Attendant call lights
To call the CCM stations from the flight deck, push the ATTEND button 2 times. The call is inhibited if the CCM handheld is being used.
Calls to the flight deck can be made from handhelds at the forward or the aft CCM stations by pressing “2” twice. This will illuminate the Cabin Call light, and will remain so until the call is answered or cancelled.
To call the other attentand station, press 5.
Service Interphone
All external interphone jacks can be connected to the flight deck interphone system by placeing the SERVICE INTERPHONE switch to ON. The OFF position deactivates the microphone at external jacks (except the jack marked FLIGHT on the APU Ground Control Panel.)
PA System
The PA system allows CCMs using handhelds and flight deck members using any micriphone to make announcements to the cabin. The system is prioritized, and higher level priorities will override lower ones.
PA Priorities:
- Flight Deck Announcements
- Flight Attendant Announcements
- Pre-Recorded announcements
- In flight entertainment system
To address pax from flight deck, select PA on the ACP then use the PTT switch to RADIO.
From CCM, push 8 to connect the handheld to the PA system, and the PTT to make the announcement. The RESET button disconnects the handset from the PA or cancels calls.
CVR
The CVR uses four independent channcels to record flight deck audio for 120 minutes.
The channels record different areas:
- Flight Deck area conversations using the area micriphone
- The other channels record individual ACP audio and transmissions for the pilots and observers ??→If ACP is on ALT, does CVR still work?
The CVR panel has the microphone, an ERASE switch, a TEST switch, a status light, and a jack that can be used to monitor transmission during playback or during tests
Where is the Audio Control Panel?::Aft Overhead
How is ACARS accessed?::Via the Control Display Units (FMC) How many VHF radios are on board?::3. Two are connected to LRU 1 and 2, the third is for ACARS. Where are the VHF antennas located?::VHF1 on upper fuselage, VHF 2 on rear lower fuselage, VHF 3 on forward lower fuselage. Where is the HF antenna located?::On the leading edge of the vertical stab.
How do you know the HF radio is tuned?::A tone will last between 7 and 15 seconds.
What alerts can be heard through speakers and headsets?::APA, GPWS, TCAS, Windshear.
How do you use the inter-phone with the oxygen mask on?::On the ACP use the PTT set to INT.
What are the V, B, R options on the ACP?::Voice only, Radio station identifier only, Both. What does ALT mode on the ACP do?::By-passes the relevant ACP and connects single radio directly to crew member.
Which systems are unavailable with the ACP in ALT?::Handheld mic, PA system via ACP, GPWS, APA, Windshear.
Where is the ACARS management unit installed?::In the E&E compartment. How do you access ACARS on the CDU?::Using the keys, select DLK, then ACARS.
What are the indications that an ATC message is received on CPDLC?::EICAS ATC message, ATC message on CDU, hi/lo chime. How do you call a CCM station?::Push the ATTEND button two times. How do you call the flight deck from a CCM station?::Push “2” twice.
How many CVR channels are there?::4 - > One for each ACP, and one area mic.
What is indicated by an illuminated offside tuning lighit?::The radio normally associated with this panel is being tuned by another radio. What communication stations can be connected through the flight interphone system?::Ground crew at nose gear station and all flight deck positions.
When the SERVICE INTERPHONE switch is ON, additional comms jacks are available for use by ground personnel.::True. What switch would you use to alert ground personnel you would like to talk to them?::GRD CALL switch on the Overhead Panel.
Using the ACP, how many MIC transmissions can be made at one time?::One.