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A mortar is an indirect fire crew-served weapon that fires projectiles in a high-arcing ballistic trajectory. The key features of a mortar is it’s ability to fire large caliber explosive rounds over obstructing terrain or objects in support of infantry. Firing on targets, or fire missions, are typically called in by a spotter or forward observer

Crew Served

A mortar crew typically consists of three persons, although this can be reduced depending on the situation. A mortar crew is also assisted by a forward observer or spotter (this role may be assigned in the mission, or taken by a team leader or other experienced member as required). The roles of the three crew members and spotter are as below:

  • Team LeaderSpotter
    • Handles communication with the spotter over the radio
    • Computes the firing solution
    • Assists with loading during continued fire
    • Directs and mentors other crew members
  • Gunner
    • Aims and fires the weapon
  • Loader
    • Prepares and loads the rounds for the weapon
  • Spotter
    • Communications with the Mortar Team Leader via a radio
    • Will observe round strikes and relay corrections and battle damage assessments to the mortar team in an efficient manner
    • May use the Vector 21B and DAGR system to provide grid references to the mortar team
      • Alternatively will use map tools, compass and GPS

Call For Fire

For a spotter or forward observer to call in a mortar strike they must tell the mortar crew what they want to hit and precisely where it is. This is done through a radio call known as a call for fire.

Step Description Example
1. Observer Identification
  • Standard RATEL identification
Steelrain this is Foxtrot 1 – 1
2. Warning Order
Request fire mission
3. Target Location
  • A map reference to the target, hopefully 8 digits to be more accurate
Grid 1015-0995
4. Target Description
  • A quick description of target and any special info about cover or location
Enemy machine gun nest in light cover
5. Method of engagement
  • Let the mortar team know anything about friendlies, call danger
    close here if within 600m
Danger close, friendlies 400m south
6. Method of fire and control
  • Adjust fire (one round for bracketing), or Fire for Effect (in and around the area)
  • Number and type of rounds (HE, Smoke, Illum, WP)
  • Method of fire control, either fire when ready, on my command, or at a time
Adjust fire, 1 round – HE, Fire when ready

Calculating a firing solution *ACE2 Information, Not Relevant in A3 To Date

Due to the steep angle that mortars traditionally fire on, each outgoing round is not aimed in the same way that a rifle or handgun is, rather the projected distance is estimated based on the angle that the mortar barrel is at when fired and how much explosive is used to propel the round on it’s way.

Working out the direction to target (Deflection)

When firing the mortar targets are aimed by giving a deflection or difference figure from the initial position of the barrel. To calculate this deflection we need to know three things:

  • The mortar’s current grid reference (8 digit grid preferred. eg: 1085 2034)
  • The mortar barrel’s initial heading (in milliradians* See below)
  • The target’s grid reference (8 digit grid preferred)


Milliradians is the measure of the angle of a circle. Much like degrees, although while there are 360 degrees in a full circle, there are 6400 milliradians in a circle – making it much more accurate.

To work out the overall direction to the target there are two main ways in ACE:

  1. Use the DAGR
  2. Use the Maptools

There are pros and cons to each method. Using the DAGR is arguably quickly, especially if you use Axyl’s clickable map DAGR mod, although it will give the result in degrees which is slightly less accurate, as well some maps are not 100% compatible with the DAGR and may give unusual readings. Using Maptools is a little more time consuming, and although it gives the result in milliradians, it can be hard to read resulting in slightly incorrect directions. As a dealbreaking positive, in some instances the DAGR may not work properly and Maptools will be the only way you can find the direction.

Working out direction to target using a DAGR

  1. Open up the DAGR Main Menu (Shift + Home)
  2. Enter the grid into the DAGR (Either via the ‘Enter Waypoint’ menu item on the DAGR or by using Axyl’s clickable map DAGR mod
  3. Use the ‘Goto WP’ option and select the newly entered grid
  4. Press the Home key to open the DAGR info screen
    1. The track figure (bottom left) is the direction to the target in degrees
  5. Multiply the track figure by 17.8 to get the approximate milliradian direction to the target


Working out direction to target using MapTools

  1. Open the standard map
  2. Press and hold [ and click on the mortar location
  3. Press and hold ] and clock on the target location
  4. Hold mouse cursor over the beginning of the line (mortar location) and press H
    1. A compass should appear, with the centre point now located on the mortar position
  5. Hold the mouse cursor over the end of the line (target location) and press J
    1. The compass should now re-orient so that the black dot is still on the mortar position the the red line is facing toward the target
  6. Read the numbers on the outside of the compass to show the direction in milliradians – note that they are in divisions of 100, so being at 5 means 500milliradians. Conversely halfway between 5 and 6 would be 550 milliradians.