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record bridge audio from a dedicated reserve source of power for at least
two hours. Recording should be continuous. All stored data items should
be retained for at least 12 hours. After that, older data items may be
overwritten with new data.

The final recording medium must be installed in a protected capsule of
either a fixed or float-free type. In both cases, the unit must maintain the
recorded data for a period of at least two years following termination of
recording, and be of a highly visible color and marked with retro-reflective
material. The capsule must be capable of being accessed following an
incident but secure against tampering. For a fixed data capsule
installation, the following survivability specifications apply to both VDR
and S-VDR:

• Impact shock – 50g for 11 milliseconds
• Fire – 1100°C for 1 hour and 260°C for 10 hours

• Deep sea pressure and immersion – 24 hours at 6.000 meters depth,
and 30 days at 3 meters depth The VDR specification also requires the
following:

• Penetration – 250 kg mass dropped 3 meters impacting with 100 mm
diameter pin The fixed capsule must have a release mechanism to
facilitate recovery underwater by a diver or ROV, and must be equipped
with an acoustic underwater beacon with a battery life of at least 30 days.

For a float-free capsule (S-VDR only), the following specifications apply:

• Homing transmitter operating on 121.5 MHz
• Flashing light

• Capable of resolving and transmitting position with a minimum of 4
seconds of arc

• Battery life of at least 7 days for transmitter

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