Intent and Scope:
- The intent of the guide is to provide the basic skills and techniques in order to fill the roles of an artillery Fire Direction Center as well as Crew a howitzer.
- The scope of this guide extends to the features of the ITC Land Systems modification, as it provides the most accurate simulation of artillery for ArmA 3.
- 1 Mission and Use of Field Artillery
- 2 Preliminary Knowledge
- 3 Fire Direction (Battery Control System)
- 3.1 Setting up the Battery
- 3.2 Receiving a Call for Fire
- 3.3 Calculating a Fire Mission
- 3.4 Message to Observer
- 3.5 Calculating Adjustments
- 4 Operating the Howitzer
- 5 Links and References
Mission and Use of Field Artillery
The mission of field artillery is to provide artillery and rocket fires in support of maneuver units. Typically artillery relies on cannons known as howitzers, or long-range rocket and tactical missile launchers to deliver indirect fire. Artillery can fulfill several roles including destruction, suppression, obscuration, battlefield illumination, area-denial, and suppression of enemy air defense (SEAD). Although heavy mortars can be included with typical artillery, in the scope of ArmA, light and medium mortars are attached directly to infantry units. Due to the increase in range and destructive power of artillery compared to light mortars, artillery operates using different procedures.
This guide assumes the reader has a competent level of land navigation ability, and radio communications ability. Some things to note that depart from the standard practices of these two skills.
Mils vs Degrees
While most land navigation is done using degrees, indirect fire demands a higher level of precision at the Observer, FDC, and Gunline levels. As such, mils re the standard unit of angular measurement whenever any type of indirect fire is being employed. While there are 360 degrees in a circle, there are 6400 mils in a circle.
For indirect fire, clear communication of data can mean the difference between an effective fire mission and dead friendlies. Two practices are used to ensure this. First, numbers are always read off by their digits, unless they have either two or three zeros.
For example a direction of 1435 mils is read off as
"ONE FOUR THREE FIVE"
3200 however can be read off as
"THREE TWO HUNDRED"
or 1000 as simply
Secondly, it is almost universal that any data is repeated by the receiver to be verified by the sender. Data is generally read off clearly and slightly slower to account for recording of data.
Finally, the term "Repeat" is never used when asking to resend a transmission, as the word in the context of a call for fire indicates the FO would like the same mission re-fired by the firing unit. "Re-send" or "Say again" should be used.
Fire Direction (Battery Control System)
The ITC mod uses the SPG tablet, available both inside the aforementioned vehicles and as a standalone inventory item. This allows fire direction to be conducted by a member of the, or outside the howitzers. Within the tablet is the Battery Control System (BCS) app. This is used to calculate solutions for fire missions received from a Forward Observer. While each howitzer is capable of using this system, it is faster and more consistent to have a single player calculating solutions for the entire firing unit. This guide will assume that this is the case.
The SPG tablet and BCS are also capable of calculating solution for the ACE mod Mk6 82mm mortar.
Setting up the Battery
Opening the SPG Tablet
The SPG tablet can be opened either from inside the commander's position of the vehicle, by holding the ACE Interact Key and selecting "Open Mounted Tablet"
If the tablet is in the player's inventory, it can be opened by holding the ACE Self-Interact Key and selecting the tablet.
Select the BCS app.
Select the Bty Setup option and enter the required information.
Save the gun(s) once information is complete.
Receiving a Call for Fire
Once the BCS is properly set up, and communication with the forward observer(s) and gunline has been established, the FDC is ready to receive calls for fire.
Observer ID and Warning Order
The first transmission from a forward observer in a call for fire will be the observer's call sign, and a warning order indicating the type of mission requested, and method of target location being used. Mission types will dictate how the fire mission will be conducted.
- Adjust Fire - The observer requests one round be fired from one gun and adjusted until on target.
- Fire for Effect - The observer requests the entire firing unit fires at the target without adjusting first.
- Suppression - The observer requests the firing unit suppress a target with fire for a certain duration of time.
- Immediate Suppression - The observer requires immediate fires on a target of opportunity or immediate effects. Typically has a pre-determined amount of rounds to reduce the time needed to transmit to the gun line.
- Immediate Smoke - The observer requires immediate screening to quickly mask friendlies or obstruct an enemy's vision.
Methods of Target Location
These will correspond to how the mission is entered into the BCS. Information on each method's use in the BCS can be found in the next section. A more detailed explanation of each method can be found in the Forward Observer guide.
- Grid - A grid reference and possibly altitude is given. Typically at minimum a 6-digit grid.
- Polar - A direction and distance from the observer's position to the target is given.
- Shift - A lateral shift, range shift, and vertical shift is given from a known point to the target. Note: the name of the known point will be given in the warning order.
"FDC, this is FO. Adjust Fire, Polar, Over."
"FO, this is FDC. Adjust Fire, Polar, Out."
An example of an FO requesting an adjust fire missions using a polar-plot method of target location. Note the repetition of the transmission back to the sender.
Once the ID and Warning Order are received, the FO will send the data for the target's location.
For a grid this will entail the grid and possibly altitude of the target.
"123 456, Altitude 205, Over."
For a polar plot, a direction in mils, and distance in meters from the observer to the target is given.
"Direction 3400, Distance 1600, Over."
For a shift, the Observer to Target (OT) Direction, Lateral Shift, Range Shift, and Vertical (elevation) Shift are given.
"OT Direction 2700, Left 500, Add 150, Down 50, Over."
As before, this transmission should be repeated back to the observer.
Target Description & Requests
The third transmission consists of the observer describing the target, including what it is, how many, actions, degree of protection, and the size/shape/orientation of the intended target area. All these factors will inform the FDC as to what type of ammunition and fuze as well as amount of ammunition used to engage the target.
In addition to description, this transmission may include several requests by the observer as to how the mission is fired.
Calculating a Fire Mission
Polar Plot Mission
Shift from Known Point Mission
Once the target location is input, the BCS must be configured for the type of engagement.
The FDC will decide how they wish to engage the target, depending on the target description received from the FO and ammunition availability.
The type of projectile the solution will be calculated for, keep in mind that each round has its own ballistics, so ensure if round type is changed during a mission, the solution is recalculated for that projectile.
For and adjust mission, HE with a Point Detonating fuze is standard, even if the fire for effect will be using another round. Ensure that the initial solution is using HE, as ammunition type can be changed once adjusted onto the target.
The sheaf is the pattern of impacts, and the adjustments to each gun used to achieve this pattern.
- Parallel - Each gun fires at the same azimuth, resulting in the pattern of impacts more or less matching the position of each gun. Provides reasonable spread and faster transmission of firing data to gunline.
- Converged - Each gun fires at the same point, converging their rounds. Useful for destruction missions.
- Open - Each gun fires roughly 60m apart, ensuring maximum coverage of a large target area. Useful for larger target areas, moving targets, or suppression missions.
- Linear - Each gun fires roughly 40m apart. Slightly tighter impact area from open.
- Special - Guns fire to cover a specific-sized area, and specific direction (i.e. not perpendicular to the gun-target line). Used when requested by an observer.
- Ensure that Quick Sheaf is off if length and direction inputs are used.
Once the engagement is configured, the next screen is the firing solution screen.
- Each gun in the battery will be displayed along with the Propelling Charge Zone, Azimuth, Deflection (not used), Quadrant (Elevation), and Time of Flight
- The SLN - and SLN + buttons will cycle the solutions between available trajectories. Keep in mind that for High Angle requested missions, Quadrant should be above 800 mils.
- The Shot button will start a countdown timer until impact of the first salvo, can be used to inform the observer of Splash.
- The Adjust/FFE buttons will be used in an adjust mission covered later.
Other information listed
- Max Ord: The highest altitude in meters the projectiles will reach. Helpful for de-conflicting with aircraft and ensuring rounds will clear any terrain or obstructions.
- Impact Angle: The angle the round will impact in relation to the terrain (in degrees?)
- Target Distance: Distance in meters from the firing unit to the target.
Message to Observer
The message to observer is the radio transmission from FDC to FO confirming the details of the mission to be fired. It consists of:
- Firing unit callsign
- Changes to the FO's requests
- Number of Guns
- Number of Rounds (per gun, not total)
- Target Number (corresponding to the FM number)
- Time of Flight (if requested)
FO, FDC. Message to Observer. ICM in Effect. 3 Guns, 5 Rounds. Target Number 003. Time of Flight 34.5, Over.
The FO will respond, and also include their OT direction, if not already given. Ensure this OT direction is recorded regardless of mission type, as it will be needed for adjustments.
FDC, FO. Message to Observer. ICM in Effect. 3 Guns, 5 Rounds. Target Number 003. Time of Flight 34.5. OT Direction 4500, Out.
In this MTO, the FDC changed the projectile used the FFE to ICM.
The FO will provide adjustments during and adjust mission, or may wish to repeat the other missions with adjustments. In either case, ensure you have an accurate OT direction before entering adjustments.
Left 400, Drop 800, Over.
An example adjustment received from an FO, indicating an adjustment left 400 meters from the OT Line, and 800 meters shorter along the OT Line.
Once adjustments have been received from the forward observer, pressing the Adjust/FFE button on the solutions screen will bring up the Adjust Mission screen.
Once all adjustments are entered, pressing next will bring up the solutions screen once again with new adjusted solutions.
Ending a Mission/Recording Targets/Refinements
Operating the Howitzer
Ammunition Handling Interface
(Adapted from the ITC Wiki)
The Ammunition Handler & Autoloader interface is accessible from the gunner's position by use of the ACE Interact Key. The Menu on the left displays the howitzer's current inventory of ammunition.
- HE - High Explosive. Blast and Fragmentation effects. Useful against almost any target.
- SMOKE - Bursting Smoke round. Useful for obscuration/screening, or for marking targets for aircraft in daylightaytime.
- ILLUM - Illumination. Used for battlefield illumination. FDC should ensure that target altitude is 700 meters above the actual terrain elevation for effective illumination.
- ICM - Dual-Purpose Improved Conventional Munition. Bursts above target dispensing several sub-munitions that are effective against exposed troops, vehicles, and light armor.
- GPS GUIDED - GPS Guided High-Explosive. Similar effects as standard HE, but with greater accuracy, assuming an accurate 8 or 10-digit grid of target is given. Useful for destruction of point targets such as stationary vehicles or buildings.
- This round should be fired at high-angle whenever possible to ensure best reliability.
- LASER GUIDED - Laser Guided High-Explosive. Similar effects as standard HE, but with greater accuracy. See ITC wiki for information on use of this round.
- MAP - Mines, Anti-Personnel. Bursts above target and distributes anti-personnel mines. Used for area-denial to enemy troops and light vehicles.
- MAT - Mines, Anti-Tank. Bursts above target and distributes anti-tank mines. Used for area-denial to heavy vehicles and armor.
- EXTRA - Sensor-Fuzed Anti-Tank Submunition. Bursts above the target and distributes independently targeted sub-muntions that seek and destroy vehicles within their field of view. Useful against vehicles and armor.
- Only available for 155mm.
- PD - Point Detonating. Fuze detonates on impact. Useful general purpose fuze to engage almost any exposed target or structure.
- DELAY - Delayed Action. Fuze detonates a set time after impact. Useful for targets under thick forest, inside buildings, fortifications with overhead cover.
- PROX - Proximity. (Also known as Variable-Time/VT) Fuze detonates a set distance above the ground. Useful for targets that are exposed, in trenches or ditches with no overhead cover.
- TIME - Time. Fuzes detonated after a user-set time. Used for all cargo rounds (ICM, ILLUM, MAP/MAT) EXTRA, fuze time should be calculated by FDC. Can also be used with HE to fine-tune height of burst for targets on rooftops or other difficult to hit positions.
- A box for entering time setting is included below the fuze menu.
The amount of propelling charge being used must be selected before loading. Charge will be given by the FDC. Zones 1-5 are available, displayed above the fuze. Charge zone can be increased or decreased by using the - and + buttons next to "Charge"
The number of rounds to be automatically loaded by the autoloader. If the gunner wishes to control when each round is loaded, set to 1.
Once Projectile, Fuze, and Charge are selected, the user must press the "Apply Settings" button. Then the cannon can be loaded by pressing the "Load" button. Once loaded, the cannon can be unloaded using the same button. Keep in mind the cannon must be unloaded first before changing any projectile, fuze, fuze setting, or charge zone.
(adapted from the ITC wiki)
The gunner's sight will display several pieces of information.
The direction in mils the cannon tube is oriented.
- CUR: The current azimuth of the tube. The turret is traversed left and right using the Mouse.
- MIS: The azimuth of the current mission loaded into the howitzer's FCS.
The elevation in mils the cannon tube is elevated to.
- CUR: The current elevation of the tube. The tube is elevated and depressed using the Page Up and Page Down keys.
- MIS: The quadrant of the mission loaded into the howitzer's FCS.
- Status: the current status or state of loading the autoloader is in.
- In parentheses is the round number being loaded and the total rounds to be loaded by the autoloader.
- Load: the current projectile and charge loaded or being loaded.
- Fuze: The fuze and fuze setting loaded or being loaded.
- Guidance: The guidance setting being used.