VOLUME I Multinational Maritime Tactical Instructions and Procedures

(2) VDS may be employed in the active or passive mode. No active sonar transmissions or other
signals are required, provided the response to the VDS/DTAS NOTE has been received from the
SMAA.
NOT RELEASABLE
(3) VDS/DTAS Safety Precautions
(a) The VDS/DTAS NOTE described below is required for safety whenever a VDS/DTAS
device is to be streamed to a depth greater than 30 meters (98 feet). A VDS/DTAS NOTE is also
required for operations at 30 meters (98 feet) or less when:
i. The water depth is less than 375 meters (1,200 feet).
ii. Operation within 40 nautical miles of the Norwegian Coast.
iii. Operation in the Aegean Sea north of Crete.
iv. Operation in the French national exercise areas.
(b) The required VDS/DTAS NOTE is to be sent to the appropriate SMAA at least 48 hours
before commencing the operation. Upon receipt of the VDS/DTAS NOTE, the SMAA is to send a
message to the originator of the VDS/DTAS NOTE confirming that there is no safety hazard. If a
risk of collision between the VDAS/DTAS and a submarine is apparent, the SMAA will advise
those concerned and request that appropriate action be taken to eliminate the hazard. VDS and
DTAS are not to be streamed until the ship is in receipt of the SMAA confirmation message, except
as noted in paragraph (5).
NOT RELEASABLE
(c) Once the confirmation message is received, the ship may employ VDS/ DTAS in the active
or passive mode and no active sonar transmission or other warning signals are required.
NOT RELEASABLE
(4) A ship planning to stream a CATAS at depths greater than 30 meters (98 feet) is to send a
CATAS ADVISORY, using the message format in APP-11, to the appropriate SMAA at least 48 hours
before commencement of the operation. Upon the receipt of the CATAS ADVISORY, the SMAA is to
send a reply to the originator of the CATAS ADVISORY acknowledging receipt. In the acknowledgement,
the SMAA may include advice on other units conducting surveillance in the area or advice on best
placement of the sensor for minimizing mutual interference and avoiding duplication of effort. Upon receipt
of the acknowledgement, and after considering the SMAA’s advice, the ship may stream its
CATAS as stated in the CATAS ADVISORY. If the towing ship departs the CATAS ADVISORY area
and the system cannot be recovered, the towing ship is to provide warning on sonar or underwater telephone,
as described in the Sonar Signal Code Table of AXP 1, at least once every 5 minutes unless otherwise
specified by the SMAA.
(5) and (6) NOT RELEASABLE
MTP 1(D), Vol. I
6-113 CHANGE 2