AIRPLANE
OPERATIONS
MANUAL
NAVIGATION AND
COMMUNICATION
REVISION 29
2-18-25
Page
1
Code
01
COCKPIT VOICE RECORDER
The Solid State Cockpit Voice Recorder System records all audio
signals transmitted and received by the crew members via the Digital
Audio Panels, and any audible noise in the cockpit, through an area
microphone installed below the standby compass.
The CVR is in operation whenever the essential DC Bus 2 is
energized, storing the last 2 hours of recorded information in a solid
state crash survivable memory unit. Any data older than 2 hours is
automatically overwritten by the most recent audio inputs.
A crash impact switch cuts off power to the CVR immediately after
experiencing a 5 G impact in order to preserve the recorded data.
The CVR also incorporates an Underwater Locator Beacon (ULB).
Powered by a dedicated battery, the ULB starts transmitting an
acoustic signal in the 37.5 kHz frequency once it senses contact with
water, thus easing wreckage site location of a submerged airplane.
The signal is transmitted during approximately 30 days.
A signal from the captain’s clock allows timing correlation between
CVR and FDRS.
SELF TEST
When the TEST button is pressed the unit performs a functional
self-test to verify the integrity of the system. A successful self-test
results in a one-second activation of the status LED on the control
panel and a two-second tone (800 Hz for Honeywell equipment and
620 to 660 Hz for L3 equipment) that may be heard from a headphone
plugged to the CVR control panel jack. If a failure is detected during
the test, the status LED will not be activated and the aural tone will not
be heard.
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