NMFS Biological Opinion on U.S. Navy training ... - Govsupport.us

FINAL PROGRAMMATIC BIOLOGICAL OPINION ON U.S. NAVY ACTIVITIES IN THE HAWAII RANGE COMPLEX 2008-2013
Sonar Systems Associated with Submarines. Submarines are equipped with a variety of active and passive sonar
systems that they use to detect and target enemy submarines and surface ships. However, submarines rarely use
active sonars and, when they do, sonar pulses are very short.
Sonar Systems Associated with Aircraft. Aircraft sonar systems that typically operate during a RIMPAC exercise
include sonobuoys and dipping sonar. Current dipping sonar systems used by the Navy are either AN/SQS-22 or
AN/AQS -13F. AN/AQS -13F is an older and less powerful dipping sonar system (maximum source level 216 dB re
µPa-s 2 at 1m) than the AN/AQS -22 (maximum source level 217 dB re µPa-s 2 at 1m). In its modeling, the Navy
assumed that all dipping sonar were AN/AQS -22. P-3 aircraft may deploy sonobuoys while helicopters may deploy
sonobuoys or dipping sonars (the latter are used by carrier-based helicopters). Sonobuoys are expendable devices
used by aircraft for the detection of underwater acoustic energy and for conducting vertical water column
temperature measurements. Most sonobuoys are passive, but some can generate active acoustic signals, as well as
listen passively. Dipping sonar is an active or passive sonar device lowered on cable by helicopters to detect or
maintain contact with underwater targets. During RIMPAC, these systems active modes are only used briefly for
localization of contacts and are not used in primary search capacity.
Torpedoes. Torpedoes are the primary anti-submarine warfare weapon used by surface ships, aircraft, and submarines.
The guidance systems of these weapons can be autonomous or electronically controlled from the launching
platform through an attached wire. The autonomous guidance systems are acoustically based. They operate either
passively, exploiting the emitted sound energy by the target, or actively ensonifying the target and using the received
echoes for guidance. All torpedoes used for anti-submarine warfare during RIMPAC exercises would be located in the
range area managed by PMRF and would be non-explosive and recovered after use.
Acoustic Device Countermeasures. These countermeasures act as decoys by making sounds that simulate submarines
to avert localization or torpedo attacks.
Training Targets. Anti-submarine warfare training targets are used to simulate target submarines. They are equipped
with one or a combination of the following devices: (1) acoustic projectors emanating sounds to simulate submarine
acoustic signatures; (2) echo repeaters to simulate the characteristics of the echo of a particular sonar signal reflected
from a specific type of submarine; and (3) magnetic sources to trigger magnetic detectors.
Range Sources. Range pingers are active acoustic devices that allow each of the in-water platforms on the range
(e.g., ships, submarines, target simulators, and exercise torpedoes) to be tracked by hydrophones in the range transducer
nodes. In addition to passively tracking the pinger signal from each range participant, the range transducer
nodes also are capable of transmitting acoustic signals for a limited set of functions. These functions include
submarine warning signals, acoustic commands to submarine target simulators (acoustic command link), and
occasional voice or data communications (received by participating ships and submarines on range).
Other Training Activities During RIMPAC Exercises
In addition to the anti-submarine warfare exercises, RIMPAC exercise typically include the following activities:
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