and the increased evacuation workload placed a strain on the existing aeromedical evacuation resources. Therefore, additional medical aviation units were requested for Vietnam based on projected increases in the US and Free World Military Assistance Forces. Until these added medical aviation units arrived, the increased evacuation requirements were met by a special issue of six helicopters by USARV to augment the medical evacuation capability. The special issue aircraft were assigned to "Dustoff" units according to demonstrated workload requirements. By the end of the year the brigade was performing the aeromedical evacuation mission with two air ambulance companies and eight helicopter ambulance detachments, which represented a doubling of the number of available air ambulances. The additional air ambulance units permitted a greater degree of flexibility in stationing, so as to provide more responsive support. From the widely scattered unit base heliports, individual air ambulances were field sited to increase responsiveness to combat forces engaged in operations. A total of 88,696 patients were evacuated by "Dustoff" units during 1967. Aeromedical Evacuation Statistics 1967 Aircraft maintenance required close attention at all levels of command due to low aircraft availability rates. To provide increased availability, non-divisional aviation units, equivalent in size to the air ambulance company, were augmented with an organic direct support level maintenance capability. In addition, these same units were furnished back-up support from field army level direct support units from the 34th General Support Group. Medical units were not augmented with a direct support level maintenance cap­ability as were the non-medical evacuation units of similar size. Since medical units received support from the same direct support units which were furnishing backup support for the non-medical units, the aircraft availability rate of medical units was less favorable. The medical mission, coupled with the absence of an organic direct support maintenance capability, prompted the aircraft maintenance support units to give "Dustoff" the highest priorities. Every effort was made to meet the Department of the Army goal of 80% aircraft availability but an availability rate of 70% was considered acceptable due to maintenance support limitations. Many evacuation missions could be accomplished only with the aid of a hoist due to the heavy jungle canopy. Hoist missions, although extremely dangerous and employed only as a last resort, often provided the only opportunity for evacuating the wounded. Insufficient hoists were introduced into Vietnam and the attendant maintenance difficulties reduced the total number available for "Dustoff" use.