text: Sustainment
  Note. Although the role 3 hospital is a medical brigade asset dependent upon the scenario and area
  of operations, the combat support hospital could be located closer to the patient or located in the
  area of operations laterally (central) to a role 2 facility. Depending upon the severity of the injury,
  location of appropriate medical treatment facilities, and available clinical specialties that the
  patient may require based on clinical judgment, the role 2 medical treatment facility (with or
  without fire support task) may be bypassed and a particular role 3 element selected as the medical
  evacuation destination for a particular patient with particular injuries. (Refer to FM 4-02,
  ATP 4-02.2, and ATP 4-02.10 for more information.)
  Casualty Evacuation
  7-40. CASEVAC involves the unregulated movement of casualties using predesignated tactical or logistic
  aircraft and vehicles. These vehicles and aircraft are not staffed with medical personnel and organic medical
  equipment for en route care unless augmentation is planned in the operational plan. If the combat medic is
  not available to provide care en route, the combat lifesaver may accompany the casualties to monitor their condition.
  CASEVAC
  Casualties transported in nonmedical vehicles may not receive proper medical care during
  transport. If the casualty’s medical condition deteriorates during transport, or the casualty is not
  transported to the appropriate medical treatment facility, an adverse impact on prognosis and
  long-term disability or death may result.
  SUPPORT AREAS
  7-41. A logistics support area is a designated location where sustainment elements, some staff elements, and
  other elements locate to support unit operations. Support areas represent an echelon of support. The method
  employed to echelon support is a deliberate, collaborative decision, based upon thorough mission analysis
  and the MDMP conducted by the leadership and staffs at the brigade, squadron, and troop levels. The primary
  support area for units conducting reconnaissance and security operations is the BSA. Trains are echeloned
  forward to provide fluid support to units conducting reconnaissance and security operations. The positioning
  of FLEs and FARPs are essential to reconnaissance sustainment planning.
  TRAINS
  7-42. Trains are a grouping of unit personnel, vehicles, and equipment organized to provide sustainment.
  Units use the trains concept to arrange their subordinate sustainment elements. Squadron combat trains are
  usually under the control of the headquarters and headquarters troop commander or the S-4 and assisted by
  the S-1. Squadron field trains are under control of the FSC commander. Troop trains are usually under control
  of the troop commander or executive officer. The composition and location of unit trains vary depending
  upon the number of units attached to or augmenting the unit, as well as other mission variables. Trains have
  two basic configurations: as unit trains in one location (appropriate when the squadron consolidates during
  reconstitution and during major movements) or as echeloned trains. Considerations include the following:
  * The troop commander determines the troop trains, which may consist of the troop first sergeant,
  supply sergeant, and troop medical assets. Maintenance teams from the FSC may be included.
  * The FSC forms the squadron field trains and portions of the squadron combat trains. The squadron
  commander and staff, the BSB commander and staff, and the FSC commander must collaborate
  to determine the best method of employment commensurate with the support brigade concept.
  7-43. The trains should change locations frequently depending upon available time and terrain. The trains
  change locations to provide the forward support to the Cavalry unit, when an area becomes unusable because
  of environmental conditions, or to follow protection (survivability) operations.