text: Environmental and Terrain Considerations for Fire Support
  * Because of a fluid FLOT, designators may have to reposition more often.
  * Weather effects on the employment of laser designators and range finders.
  D-27. The mix of munitions used by indirect fire systems will change somewhat in urban areas. Supporting
  unit commanders rely on their FSCOORDs to understand ammunition effects and to correctly estimate the
  number of volleys needed for the specific target coverage. Increased use of certain munitions (for example
  Excalibur and other HE or smoke rounds, and precision guidance kit, delay, and concrete-piercing fuzes)
  should be anticipated.
  D-28. Special considerations apply to shell and fuze combinations when buildings limit effects of munitions:
  * Indirect fires may create unwanted rubble and collateral damage. Precision and precision-guided
  munitions can be used to minimize rubbling.
  * The close proximity of enemy and friendly troops requires careful coordination of fires.
  * Swirling winds may degrade smoke operations.
  * White phosphorus may create unwanted fires and smoke.
  * Fuze delay should be used to penetrate fortifications or tops of buildings.
  * Point detonating fuzes on delay typically penetrate only the first wall or roof of a structure. The
  MK 399 concrete piercing fuze is used when added penetration is necessary.
  * Use of visible illumination may favor the defender who lacks night vision devices.
  * Illumination rounds can be effective; however, friendly positions should remain in shadows, and
  enemy positions should be highlighted.
  * Tall buildings may mask the effects of illumination rounds. Illumination rounds fired to burn on
  the ground or on a building can also be used to mark targets for aerial support.
  * Airbursts (variable time or time fuze) and improved conventional munitions are effective for
  clearing those antennas and enemy observers located on rooftops and for suppressing enemy fires.
  * Variable time fuzes may detonate prematurely due to the proximity of other structures.
  * Observer-adjusted time fuzes may be better to use among buildings with varying heights.
  * If the area will be crossed by friendly or civilian personnel, units may choose not to use improved
  conventional munitions. Such circumstances include residual hazards created by unexploded
  ordnance form improved conventional munitions which fail to function or if the enemy is in a
  building with several floors which offer overhead protection.
  * Scatterable mine effectiveness is reduced when delivered on a hard surface.
  DIRECT FIRE
  D-29. Artillery may be used in the direct fire mode. Commanders, in consultation with their FSCOORD and
  FSEs, determine the parameters under which FA assets can be used as direct fire platforms. Normally, FA is
  employed in direct fire only where tanks, Bradley fighting vehicles, and other direct fire systems are not
  available to engage the target. In this case, subordinate and supporting unit commanders, in coordination with
  their respective FSCOORD and fires cell planners, direct the employment of individual howitzer sections to
  support the unit in contact. Commanders should identify their most proficient direct fire sections.
  D-30. Self-propelled systems can take advantage of the systems' mobility to support multiple elements. FA
  used for direct fire will likely require shuttling between indirect fire and direct fire positions. One or more
  sections may need to follow a supported force closely if sustained direct FS is needed. Self-propelled
  howitzers are effective in neutralizing or destroying bunkers, heavy fortifications, or enemy positions in
  reinforced concrete buildings. Concrete-piercing 155-mm rounds can penetrate 36 inches of concrete at
  ranges up to 2,200 m. If care is taken, self-propelled artillery can be used to clear or create avenues of
  approach. Due to the self-propelled howitzer's limited armor protection, infantry will be required to provide
  security from enemy snipers and antitank teams.
  D-31. Although towed artillery can be used in a direct fire role, it is not preferred because it does not have
  any ballistic crew protection. This lack of protection should not preclude the use of towed artillery if the
  situation calls for it and the commander is willing to accept increased risk of crew casualties. For some direct
  fire situations, the light 105-mm howitzer may be more adaptable especially for fires against dismounted