Doctrinally, the division of responsibility between air ambulances organic to a division and Army-level, or Dust-off helicopters, was clear cut. Divisional air ambulances evacuated patients in the division's area of operations from the site of wounding to one of the division's four clearing stations. Dust-off helicopters evacuated patients from the divisional clearing station to an Army hospital. In practice, the line of demarcation was often blurred. During lulls in combat, divisional aircraft flew patients from the clearing station to a hospital, while during peak periods of combat, Army-level helicopters supplemented divisional aircraft and evacuated casualties from the frontline to the divisional clearing station. Occasionally, assault helicopters were used when the medical air evacuation platoon was overtaxed, but Dust-off was preferred because the medical aidman aboard could give emergency treatment and because the patient could be regulated to the hospital best suited to his needs.

In contrast to the usual practice in Vietnam of evacuating a casualty directly from the site of wounding to a, hospital by air ambulance, 95 percent of the casualties in the 1st Cavalry Division (Airmobile) were first evacuated to one of the division's clearing stations, because of the size of the division's area of operations. The remaining 5 percent, severely wounded or critically ill patients who could not have survived a stop en route, were evacuated directly to the 45th Surgical Hospital in Tay Ninh or the 2d Surgical Hospital in Lai Khe.

Since there was no difference in flying time from the combat area to the helipad of the clearing station of the 15th Medical Battalion (Airmobile) and that of the 45th Surgical Hospital at Tay Ninh, patients were evacuated to the clearing station. The two units complemented each other. Personnel at the clearing station became adept in the triage of combat casualties and in the techniques- such as administering blood and reducing shock- of stabilizing a seriously wounded patient. Surgeons at the 45th Surgical Hospital, in turn, were, freed to devote their full effort to resuscitative surgery without fear that the condition of patients awaiting surgery would deteriorate. The clearing station handled a surprisingly large number of casualties in a short period of time. It also weeded out the slightly wounded and the "sick, lame, and lazy" who would have become the responsibility of the 45th Surgical Hospital had they been evacuated there originally.

25th Infantry Division

In contrast, to the relationship between the 15th Medical Battalion. (Airmobile) and the 45th Surgical Hospital, casualties from the 25th Infantry Division, which also operated in the Tay Ninh area, were