Gunnery Officer



Information Sheet Number: 1.24


The MK 34 Gun Fire Control System (GFCS) is an integral part of the Aegis combat weapon system on DDG-51 class ships. It is used to engage surface, air and shore targets. Officers assigned to DDG-51 class ships should be familiar with the MK 34 GFCS as they are often times responsible for the system and the people trained to operate and maintain it.


(a) SW221-AD-MMO-010/MK 34 MOD 0


1. MK 34 GFCS can maintain a track file on up to four Surface Direct Fire (SDF) or Antiair (AA) targets assigned by Command and Decision (C&D), and a maximum of 10 NGFS targets entered at the Gun Console (GC).

2. When a specific assigned target is designated for engagement, the Gun Computer System (GCS) MK 160 Mod 4 computes two fire control solutions (primary and secondary) depending on the type of projectile to be fired. Gun orders based on the selected projectile's solution are sent to the gun mount. (Only one target can be engaged at a time.)


1. The Gun Computer System (GCS) MK 160 Mod 4 accepts target data from the Aegis combat weapon system target sensors (i.e., AN/SPY-1D and AN/SPS-67 radars), and/or operator-entered data for indirect targets. Based on this target data, together with the ship's attitude and clock data, the GCS computes ballistic solutions and gun orders for the mount.

2. The GCS MK 160 consists of the following equipment:

a. Gun Console (GC) OJ-451 (DDG-51-58) or OJ-663 (DDG-59 up).

b. Gun Console Computer (GCC) consisting of a Data Processing Set (DPS) AN/UYK-44 (V) and Expansion Adapter Group (EAG) OF-174/UYK-44(V).

c. Two Signal Data recorder-Reproducer Sets AN/USH-26(V), also known as Magnetic Tape Units (MTUs).

d. Signal Data Converter/Gun Mount Processor (SDC/GMP) MK 20 Mod 0.

e. Gun Mount Control Panel (GMCP) MK 437 Mod 0.

f. Velocimeter MK 5 Mod 0 consisting of an Antenna Unit.



1. Gun Console (GC)

a. Located in Combat Information Center (CIC).

b. The GC serves as the principle operator-to-GCS interface providing target

displays, data entry displays, and an intercommunications station.

2. Gun Console Computer (GCC)

a. Consists of two Navy standard cabinets: Data Processing Set AN/UYK-44(V) and Expansion Adapter Group (EAG) OF-174/UYK-44(V).

b. Located in Combat System Equipment Room (CSER) #1.

c. Variable configuration general-purpose computer that interfaces the GCS MK 160 with C&D, ships sensors (SPY-1D and SPS-67), and Aegis Combat Training System (ACTS).

d. The GCC operational program receives and interprets operator entered commands/selections from the GC, maintains a file of targets being tracked by ship's sensors, provides smoothed target position and rates to the Signal Data converter/Gun Mount Processor (SDC/GMP), enable displays and updates of various system and target symbology, and communicates with the Aegis Combat System.

e. The GCC communicates on primary and alternate data lines and is the primary interface between the Gun Weapon System (GWS) and Aegis Combat System.

3. Signal Data Recorder-Reproducers

a. The Signal Data Recorder-Reproducers (Magnetic Tape Units) are AN/USH-26(V) and are located in CSER #1.

b. Used for operational program loading and mission recording.

c. Contains four tape drives that are unique from other DDG-51 class standard AN/USH-26(V).

d. The AN/USH-26(V) may be used to record exercises performed by the GWS (in real time), however, there currently is no shipboard data extraction or reduction capability.


4. Signal Data Converter/Gun Mount Processor (SDC/GMP)

a. Located in the Gun Mount Loader Room.

b. The SDC/GMP MK 20 Mod 0 is a digital processor and interface unit that

receives filtered target data and control commands from the GCC, and ship's attitude

(e.g., roll, pitch) and clock data from the clock/gyro data converter cabinets, to develop two ballistic solutions for the target being engaged.

c. Ballistic solutions are converted to gun train and elevation rates, and fuze orders compatible with the Gun Mount MK 45 Mod 2. One set of these orders are transmitted to the gun mount control panel (EP2) to control gun mount position.

d. The SDC/GMP provides target position data to the Optical Sight (OS)

MK 46 Mod 0. The SDC/GMP provides system status data, current operational status, and OS position to the GCC.

5. Gun Mount Control Panel (GMCP)

a. The GMCP MK 437 Mod 0 is a touch-screen, interactive display that is located in the Gun Mount Loader Room.

b. Used primarily as a test and monitoring station for various GWS functions.

c. In the event of a GC and/or GCC failure (GCS casualty configuration), the GMCP and SDC/GMP can function as a stand-alone GCS using target data (supplied via voice communications) entered manually at the GMCP. It can also function as a stand-alone unit with the OS MK 46 position display providing target bearing and with other target data (e.g., grid coordinates, range) being entered manually at the GMCP.

6. Velocimeter

a. The Velocimeter MK 5 Mod 0 antenna unit is located on the non-recoiling part of the MK 45 LWGM and interfaces directly with the SDC/GMP.

b. Used to measure initial velocity (IV) of each 5"/54 round fired from the gun mount.

c. After each round is fired, Velocimeter IV data is passed to the SDC/GMP and is used to confirm or update previous ballistic computation IV inputs.


7. Optical Sight (OS) MK 46 Mod 0

a. The Above Deck Sensor Unit (ADSU) is comprised of a two-axis stabilized director, daylight imaging sensor (DIS) assembly, and a thermal imaging sensor (TIS) assembly. It is located above the OS Equipment Room, which is located above the Pilot House.

b. The Control and Display Unit (CDU) provides the image display on a TV

monitor from the OS sensors, and contains the OS Operator controls and indicators. It is located in CIC adjacent to the Gun Console (GC).

c. The Stabilization Electronics Unit (SEU) provides the required electronics

support to position, stabilize, and route commands and signals to/from the ADSU. It is located in the OS Equipment Room.


1. Surface Direct Fire Mode. The SDF mode is used to engage surface targets being tracked by the SPY-1D, SPS-67 or Optical Sight (OS) MK 46. Targets are assigned by C&D and control of the gun engagement under normal conditions is at the Gun Console (GC). Casualty configurations allow control of the gun mount from GMP in the SDC/GMP OS mode or from either the GMCP or EP2 if the OS is not operational. The gun console operator monitors the target position and the ballistic solution processing, presses the firing key to commence fire, and evaluates the target engagement.

2. Naval Gunfire Support Mode. The NGFS mode is used to engage indirect targets that cannot be tracked directly by own-ship sensors. The NGFS mode is divided into four submodes:

a. Grid Navigational Reference (GNR)

b. Relative Navigational Reference (RNR)

c. Grid Dead Reckoning (GDR)

d. Relative Dead Reckoning (RDR)

3. Antiaircraft Mode. Operations in this mode are similar to that of the SDF mode, except that the target is an air target, which limits the sensors to the SPY-1D and the OS.

4. Support Mode. The support mode involves tracking with the SPY-1D of the trajectory of several (three to five) rounds fired specifically for this gun calibration function. The trajectory of each round fired is compared to the trajectory originally computed for that round and values of sensor/gun misalignment, meteorological data and Initial Velocity (IV) obtained. This data may then be used to update the data used to fire the original round, calibrate the GWS, and provide a more accurate fall-of-shot.







































































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