MD-11 Flight Crew Operations Manual
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Communications -
Description and Operation
Comm.10.5
The PA system also allows for the broadcast of music from the passenger
entertainment tape reproducer and for the transmission of prerecorded
announcements throughout the passenger compartment.
PA announcements from the cockpit may be made with boom microphone or
oxygen mask microphone from any audio panel.
The service interphone/PA handsets on the aft pedestal in the cockpit and at the
cabin attendant stations are also used to make PA announcements. In the cockpit,
the PA switch on the ATTND CALL panel must be pushed to transfer the handset
from service interphone to PA.
PA announcements from the cockpit have priority over the passenger
entertainment system and any PA announcements from a cabin attendant station.
Priority of the PA system is as follows:
1. Cockpit.
2. Cabin attendants.
3. Pre-recorded announcements.
4. Video system PA.
5. Boarding music.
For PA announcements, the passenger compartment is divided into three zones,
forward, mid, and aft.
The Captain, First Officer, and right Observer are able to make PA
announcements to all zones from their respective microphone or handset.
Only one PA announcement can be made at a time. To prevent simultaneous
accidental announcements, PA IN USE lights are provided at all cabin attendant
stations and on the service interphone/call panel. These lights illuminate at any
station indicating a handset is off the hook.
PA volume is automatically increased when one or more engines are running.
If the handset is secured by the handset hook, audio to the handset receiver is
turned off.
After use, returning the handset to its hanger, or actuating a service interphone call
from the cockpit, automatically transfers the PA system to the service interphone
system.
Selective Calling (SELCAL) System
Selective Calling (SELCAL) operates in conjunction with the VHF and HF
systems to provide visual and aural indications that the airplane is being called by
a ground station.
When a ground station calls the airplane, the applicable CALL light on the ACP
flashes and the Central Aural Warning System (CAWS) sounds a chime. This
chime is inhibited during takeoff or landing.
October 02, 2006
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