text: Appendix B
  B-28. A formal airspace coordination area requires detailed planning. Vital information defining the formal
  airspace coordination area includes minimum and maximum altitudes, a baseline designated by grid
  coordinates at each end, the width (on either side of the baseline), and the effective times. When time for
  coordination is limited, an informal airspace coordination area is used. In an informal airspace coordination
  area, aircraft and surface joint fires may be separated by time or distance (lateral, altitude, or a combination
  of the two). The supported commander requesting CAS or employing helicopters can request an informal
  airspace coordination area; the informal airspace coordination area is approved at BN or higher level. Both
  types of airspace coordination areas are constructed with the assistance of the ALO to ensure they meet the
  technical requirements of the aircraft and weapon systems.
  B-29. Army aviation, ADA, military intelligence, maneuver, UAS, EW assets, FS, and joint and
  multinational air and ground forces all use airspace. Commanders of BCTs and lower exercise airspace
  management as part of a division's airspace control within division assigned airspace because they are not
  organized, trained, and equipped to conduct airspace control. Airspace control maximizes the simultaneous
  use of airspace. At decisive moments, commanders can exploit all available combat power synchronized in
  time, space, and purpose.
  B-30. Fires are airspace users. Clearance of fires maximizes damage to enemy capabilities while minimizing
  the risk of damage to friendly forces and non-combatants. Clearance of fires may be accomplished through
  a staff process, control measures, embedded in automation systems, active or passive recognition systems, or
  a combination thereof.
  B-31. A formal airspace coordination area is graphically shown (see figure B-6) as an area enclosed by a
  solid black line. Depicted inside the enclosed area are airspace coordination are (known as "ACA,") the
  establishing HQ, the minimum and maximum altitudes, the grid coordinates for each end of the baseline and
  the width of the airspace coordination area, the grid coordinates for each point of an irregularly shaped
  airspace coordination area, and the effective date-time group or the words "on-order." Informal airspace
  coordination areas are not normally displayed on maps, charts, or overlays.
  Note. In NATO FA tactical doctrine the airspace coordination area is a FSCM and is defined as
  "a restricted area or route of travel specified for use by friendly aircraft and established for the
  purpose of preventing friendly aircraft from being fired on by friendly forces" (Allied Artillery
  Publication-5).