VOLUME I Multinational Maritime Tactical Instructions and Procedures

MTP 1(D), Vol. I
(b) On request of a misaligned unit.
(c) Whenever the GRU or FTCs detect misalignment of one unit only.
(2) General Grid Lock (Codeword GRID LOCK). General grid locks are undertaken:
(a) When misalignment occurs in several units.
(b) Upon activation of the net and after inserting the DLRP into the various TDSs.
(c) After changing the DLRP.
(d) When requested by FTC-A.
b. Execution of Grid Locks. The procedure of executing grid locks differs between TDS and
non-TDS units.
(1) TDS Units. This is the simple matching of the position of a single track reported over the data
link by the GRU or another unit with the same locally held radar contact in the unit(s) carrying out the
grid lock. Correction to align the link-reported track over the local contact will be in X and Y coordinates
and will be applied according to the individual system design, either by moving the DLRP in terms
of own-ship position or by applying the appropriate correction to transmitted and received tracks. Units
are to report whether or not satisfactory grid lock has been achieved.
(2) Non-TDS Units. The correct X and Y coordinates of a locally held track are reported by the
GRU or another grid locking unit, and units adjust their grid accordingly.
NOTE
The responsibility for keeping the picture aligned lies with the individual unit(s).
c. Locking Non-TDS Aircraft Into Grid. The appropriate aircraft control unit (ACU) can lock
aircraft into grid by five methods:
(1) Radar Grid Lock. On joining and after full identification procedures, the aircraft will be instructed
to stand by for grid lock and X and Y coordinates are issued.
(2) Reverse Radar Grid Lock. If for some reason the ACU is unable to use radar, a reverse radar
grid lock is executed. This requires the aircraft to use its radar and take bearing and distance from QQ or
ZZ as applicable. It is essential that the aircraft knows the position of the reference within the force so
that the fix is correctly taken.
(3) On Top. If the aircraft has permission to enter the ISR and overfly the force and can identify the
ACU, the aircraft may obtain an ON TOP grid position of the ACU.
(4) Tacan Method. EMCON permitting and when a tacan-fitted ship is in the group, an aircraft
can obtain a tacan lock of this unit and then be passed its grid position.
(5) Alternative. Individual unit position reports can also be given using bearing and distance from
a geographically fixed reference position (e.g., helicopter reference position (HRP)). When this is done,
the code word(s) (REVERSE) UPDATE is (are) to be used. An UPDATE can be given by the GRU or
another grid locking unit as a bearing and distance from the reference position to the subject unit. If for
some reason the GRU or grid locking unit is unable to use radar, a REVERSE UPDATE can be
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