Approximately two-thirds of the Army aviation resources supporting operations in Vietnam were assigned to the units, of the 1st Aviation Brigade. The remaining aircraft and men were assigned to those units organic to the divisions; relatively few were assigned to artillery, engineer, aircraft maintenance, signal, or other support units. Although the strength of the 1st Aviation Brigade was not much greater than 25,000 men, its approximately 50 flight surgeons provided primary medical care on an area basis to more than 35,000 troops. In some areas, the dispensaries of the 1st Aviation Brigade were the only source of outpatient care. The medical units of the brigade established liaison and close working relationships with their nearest supporting hospitals, referring patients for consultations, inpatient care, and specialized treatment.

The flight surgeon is a physician who has received formal training in the specialized field of aviation medicine. His mission includes the prevention and treatment of disease, injury, and mental or emotional deterioration among aviation flight, ground crew, and maintenance personnel. He monitors the programs of flyers and is expected to participate in frequent flights. He is confronted by the problems of traumatic injury; of acute and chronic disease, ranging from the common upper respiratory infections to the most uncommon of tropical diseases; of psychiatric disorders, which run the gamut front occupational fatigue through the minor disorders of personality to overt psychoses; and of personal hygiene and environmental sanitation, including dietetics, venereal disease, insect control, and a multitude of bizarre and homely worrisome matters. The flight surgeon treats physical and mental conditions that might endanger pilots or passengers. Whether in the examination room or upon the flight line, he must be able readily to detect incipient major and minor disorders of personality in men who, in their zeal to fly, frequently try to conceal the disorders. He administers and prescribes medications and treatment, and he reviews and studies the case history and the progress of the patient, He also acts as consultant in his specialty to other medical services and provides aeromedical staff advice. In addition, the flight surgeon serves as medical member of aircraft crash investigation teams and, when possible, contributes to aeromedical research and development.

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The number of flight surgeons authorized in Vietnam reached a maximum of 86 in August 1968; by November, 98 were actually assigned there. This maximum contrasted with shortages during such periods as August 1967, when these assignments fell to 40 percent below the authorized strength.

The flight surgeon, assigned to a unit of an aviation brigade, was supported by a medical detachment team which provided dispensary service. These teams were assigned generally on a basis of one detachment per two aviation companies. The unit flight dispensary was usually located next to the airfield, often in a unit billeting area, and the flight surgeon and his staff usually lived with the troops that they served. This arrangement, allowing for optimum rapport and medical services, was especially advantageous when the airfields were, under attack, and it proved vital during the 1968 Tet Offensive, when many airfields, were isolated.

The aeromedical problems that faced Army aviation, units in Vietnam provided a challenge to their supporting flight surgeons. No problem, however, was more common yet more elusive than that of flyer fatigue. It became more pronounced after 1965 when the buildup of U.S. forces gained momentum and remained a significant limiting factor in the conduct of airmobile operations. By the end of 1966, aviators were flying 100 to 150 hours or more per month, and the need to know how much an aviator could fly before, he was so fatigued that he was no longer effective or safe was evident.

Army aviators were assailed by a multitude of stresses, each to some extent capable of endangering their missions. The stress from hostile fire was aggravated by such factors as heat, dehydration, noise, vibration, blowing dust, hazardous weather, exhaust from engines and weapons, and labyrinthine stimulation. Additional stress was caused by psychic elements, such as fear, insufficient sleep, family separation, and frustration. These stresses, acting on the aviator day after day, combined with the physical exertion of long hours of piloting an aircraft, caused fatigue.

The ever-increasing requirements during the years 1967-68 for aviation support caused the accrual of extremely high aviator flying times in all units. Night operations, with their extra demand upon the critical judgment of the aviator increased. The shortage of crews often forced an individual to undertake both day and night missions without adequate rest.

In response to expressed concern of the unit commanders and of aviation safety officers, flight surgeons at all levels of aerornedical support studied every aspect of the fatigue problem. Because fatigue was the result of many variables, it defied easy definition and precise measurement.

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Emphasis, therefore, was placed on prevention- eliminating or reducing those factors in the aviator's environment that caused stress.

General Neel, Surgeon, USARV, noted in the Command Health Report for August 1968 that approximately 70 percent of aircraft accidents were found to be the result of pilot error and that pilot fatigue had been implicated as a contributing factor in a large proportion of accidents. He indicated that the only way to cope with pilot fatigue was prevention by reducing the aviator's flying hours. His recommendation was "that immediate action be taken to provide additional aviators to USARV insuring at least 100 percent authorized aviator strength to reduce the degree to which pilot fatigue is contributing to the loss of lives and expensive aircraft." This was never done.

The unit flight surgeon's close scrutiny of charts that showed each pilot's flying hours for the previous 30 days, followed by close cooperation among the unit commander, platoon leaders, operations officer, noncommissioned officers, and flight surgeon, proved an invaluable system for collecting data on which the flight surgeon based his final recommendation to the commander. By the end of 1968, this system was utilized by most of the aviation units.

Some flight surgeons, notably Captain Philip Snodgrass, MC, of the 269th Aviation Battalion at Cu Chi, believed that: the relationship of days flown to days off and, particularly, the provision of a scheduled "on-off" work cycle were more important than the total number of hours flown. Captain Snodgrass's staff study of a "goal-directed" flying-hour schedule indicated that a series of 5 or 6 days flown, followed by a scheduled day free from flying and from other duties, resulted in a unit that evidenced less fatigue and could fly even greater numbers of hours. This idea was adopted by many units and proved workable and effective.

Fatigue in the enlisted crew members was a less obvious, though very real, threat. These individuals, who accompanied the aircraft on all its missions, returned to their base camps only to work many additional hours in providing required maintenance and preparing for the following day's missions. With the added requirement of aiding in perimeter defense and in the multitudinous other details of combat aviation, they performed under great stress. Efforts by the unit flight surgeons in their behalf centered upon improving their living conditions, eliminating some extra duties, and increasing their numbers.

By 1970, fatigue as an entity was still no better defined nor more capable of measurement than before. Moreover, the attempt at limiting aviator flying hours by regulation had been proved ineffective in the combat environment, and the requirement for continued study of the problem was evidently needed.

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Flight Physicals

The problem of performing periodic physical examinations on flying personnel began with the first Army aviation unit in Vietnam. Equipment and facilities were not available for an adequate examination. This handicap was partially overcome by Department of the Army waiver of the requirement for routine periodic examinations for rated aviators in Vietnam; however, despite the waiver, many still requested them. Periodic examinations for crew chiefs, flight surgeons, and aerial observers were also waived; required initial examinations were performed as well as available equipment allowed. Modifications of organization and the addition of equipment helped eliminate these difficulties. Aerial door gunners were not given a complete examination. After reviewing their medical records, the flight surgeon gave them a general examination which included visual tests and their "Adaptability Rating for Military Aeronautics." A statement of medical qualification was then issued by the flight surgeon.

Waiver authority was retained by USARV headquarters for medical standards for pilots, crew chiefs, flight surgeons, and aerial observers. Headquarters policy on standards for pilots was strict. Policy on standards for others who were expected to participate in aerial flights was considerably more lenient; conditions were waived if they were not dangerous to the individual's health and would not interfere with mission completion.

Significant Medical Conditions

The incidence of infectious disease among aviation personnel in Vietnam generally paralleled that of other troops in the area. Many diseases, however, were more serious for flying personnel because of possible time lost from primary duties. Basic preventive medicine, therefore, was of prime importance to the unit flight surgeon.

Diarrhea and upper respiratory infections were particularly costly in terms of aviator availability. Aviation companies normally operated a single mess and, on some occasions, were rendered ineffective for short periods because of epidemic gastroenteritis. Food and ice procured from local handlers were frequent sources of these outbreaks despite constant screening and surveillance by the flight surgeon. Venereal diseases, notably gonorrhea, were of particularly high incidence.

Breakdowns in basic field medicine practices and water supply control occurred, Individual soldiers were occasionally charged with the, treatment of water without adequate, knowledge of the techniques involved. Failure to maintain adequate chlorine residual and even the

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accidental use of nonpotable supplies presented problems. In April 1968, in the 1st Cavalry Division (Airmobile), thousands of cases of gastroenteritis severe enough to cause loss from duty occurred almost simultaneously, and many more men were symptomatic without loss of duty. Investigation implicated contaminated water. The 164th Aviation Group, located in the Delta region with headquarters at Can Tho, had outbreaks of hepatitis during the summers of 1967, 1968, and 1969. Mass immunization with gamma globulin was required to abort these episodes, some of which apparently originated from using nonpotable ice and frequenting Vietnamese food establishments.

Aircrews frequently encountered skin disorders, often miliarial or fungal in etiology. The long hours of flying while dressed in protective equipment and the intense dust clouds raised by helicopter operations contributed to the adverse dermatological environment. External otitis sometimes caused restriction of flying duties.

Malaria was significant only sporadically. Basic mosquito control measures were effective in secure base areas, and it was there that aircrews usually spent their evenings. The continuous presence of the aviation unit flight surgeon with constant emphasis on preventive medicine techniques and health education for the aviator undoubtedly contributed to the low incidence.

Medication and Therapy

Traditional. aeromedical philosophy on the use of drugs by flying personnel is conservative. AR 40-501 and AR 40-8 specifically limit their use. The flight surgeon's duty was to promote a state of individual fitness that allowed the flyer to meet the myriad stresses of combat flying. Ideally, the use of systemic therapeutic agents should have been prohibited in Vietnam, as they are elsewhere, but realistically, the unit commander needed the maximum number of personnel to carry out his mission. It was the duty of the flight surgeons to evaluate the risk of using therapeutic and prophylactic agents against the impact of losing personnel to flying duties while undergoing treatment. On this basis, the flight, surgeon frequently administered certain drugs without restricting the aviator from flying, and other drugs after careful evaluation of the pilot's condition and his particular response to the drug. When the acute medical condition of an aircrewman did not prohibit flying status, he was often allowed to fly after a period of drug use to determine his susceptibility to side effects. Antibiotics and decongestants were used but antihistaminics, sedatives, and tranquilizers were prohibited.

Aviation personnel had to take the weekly malaria, chemoprophylactic tablet; those who exhibited significant side effects were evaluated by the

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unit flight surgeon and placed on chloroquine tablets if the reaction was due to the primaquine component. Many aviation units required their men to take the chloroquine-primaquine tablet on Monday night rather than on Monday morning because of the diarrhea that sometimes occurred shortly after ingestion. The incidence of glucose-6-phosphate dehydrogenase deficiency was low.

Dapsone, when introduced in Vietnam, was used only where recommended by the appropriate medical authority; a very low incidence of methemoglobinemia was evaluated in the 7/17th Air Cavalry Squadron by the unit flight surgeon and the WRAIR team in Saigon. The incidence of fungus infections prompted therapy with griseofulvin in selected aviators, who continued to fly during long-term treatment. Throughout the years of Army aviation operations in Vietnam, the practical approach to the question of therapeutic agents turned out to be effective.

Safety

Accidental injury was a source of significant personnel loss. Aircraft accidents, until the spring of 1968, caused more aircrew injury and death than did enemy action. Less spectacular but also significant were those casualties caused by weapons accidents, vehicle mishaps, and sports. Relatively simple injuries removed the patients from flying duties for the duration of treatment.

All flight surgeons participated in the flight safety program at all levels of command. In addition to their constant fatigue monitoring and their vigilant protection of the mental, emotional, and physical health of all aircrews, they served as advisers, in evaluating and proposing protective armor for both aircraft and aircrew.

Aircrew Wound Experience

The vulnerability of the helicopter when used as a tactical aircraft is extremely serious. The ways in which the vulnerability of the crew may be reduced is a significant matter. During 1965 and 1966, studies were made on the effectiveness of armor for both men and equipment. Although helicopter crashes frequently were caused by enemy fire, evidence existed that few were the result of injury to the pilot. By the end of 1965, crashes had caused 101 fatal and 79 nonfatal injuries, and "missiles and shells" had caused 43 fatal and 673 nonfatal wounds. Effectiveness of seat armor was implicit in the notation "most fatalities due to wounds of head, throat, and upper torso."

Medical input requested by the 1966 Army Materiel Command study group for a study in Vietnam was provided by representatives of

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USAMRDC (US Army Medical Research and Development Command).

In April 1966, Captain James W. Ralph, MC, produced a staff study on aviation casualty reporting for the Army Concept Team in Vietnam in an attempt to determine whether or not the data being compiled was being analyzed and could be applied to studies of protective equipment. With the collaboration of Major (later Colonel) James E. Hertzog, MC, Surgeon, 1st Aviation Brigade, and Aviation Medicine Consultant, USARV, a form was developed for reporting wounds.

In June 1966, USARV Regulation 40-42, "Wound Evaluation and Analysis," was published, requiring that specific data be reported on all crewmembers wounded in Vietnam, and placing the responsibility for implementation upon the unit flight surgeon. By early 1967, only a small percent of wound incidence had been reported because of communication and transportation difficulties. The number and, locations of the medical facilities hindered the flight surgeons' interviewing and recording the pertinent data on every wounded aircrewman. Late in the year, the regulation was amended to provide for reporting by the commander of the medical facility receiving an injured aircrewman; the amendment resulted only in total failure of the reporting system. Although the amount of wound data reported by flight surgeons in 1966 was meager, the available information showed that both personnel armor and aircraft armor were of great protective value.

Life Support Equipment

At the onset of Army aviation operations in Vietnam, crewmembers flew their support missions in H-21 aircraft, dressed in fatigues or US Air Force issue coveralls, leather gloves, and 1959 model APH-5 flight helmets. With the exception of occasional flak jackets of Korean War vintage, any additional protection was provided by makeshift means. The aircraft were not armored and were relatively vulnerable to enemy fire. In general, survival kits were also makeshift. The need for measures to increase the survivability of aircrew members was evident.

In 1962, the Army Materiel Command initiated a long-term research and development project to reduce the vulnerability of Army aircraft and aircrew. The results of this project and the related efforts of other commands, such as USAMRDC, provided much of the equipment lacking in those early years. Flight surgeons in the field provided impetus to this development effort.

While crash-injury fatalities in aircraft hit by ground fire were three times those caused by bullet wounds, the need for protection from small arms fire was recognized through work done by the US Army Ballistic Research Laboratories. By 1965, the H-21 helicopters had been phased

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out of Vietnam, and all UH-1 aircraft were equipped with armored seats for the pilot and copilot. Unfortunately, the great need for an armored seat for the gunner and crew chief on UH-1 aircraft was never met in the field, although development was undertaken.

Body armor of bullet-protective plates in a canvas carrier was introduced in 1965 for protection of the torso. It was widely accepted by aircrews. The pilot and copilot of the aircraft utilized the chest protection only, since they were otherwise protected by the armored seat. Body armor containing both front and back protective plates was worn by other crewmen of the aircraft. There are many documented cases of individuals sustaining direct hits on these protective plates without injury other than bruises.

In January 1966, the Department of the Army approved a project for the development of flight clothing which would provide fire protection, be compatible with cockpit design, and resemble the uniform worn by the foot soldier. Deliveries to Vietnam of a two-piece Nomex uniform began early in 1968, and by year's end adequate quantities were on hand to meet all requirements. In 1969, the fire-resistant flight uniform, having been well received by aircrews, was made Standard A for the Army.

Individually carried survival kits were considered necessary by most flight surgeons and aircrewmen in Vietnam early in the war. A variety of survival kits were developed and made available in quantity. However, as experience accumulated in Vietnam, it was noted that survival kits were seldom utilized by the survivors of downed aircraft. Few persons were rescued if downed in hostile territory more than a few hours. The consensus of flight surgeons and other aeromedical personnel was that items of signal equipment were most valuable. The survival radio, if working, appeared to be the most important item in the location and rescue of downed aircrewmen. Recognition of this fact led to emphasis upon the continuing development of more reliable survival radio sets.

Before 1961, flight surgeons, had cited the need for better head protection, including fragmentation protection. Early in 1967, after more than 6 years, of development, the AFH-l helmet, which met specifications, was delivered to aviation units but proved to be too small for many of the aircrewmen. Major (later Lieutenant Colonel) Anthony A. Bezreh, MC, who, as aviation medicine consultant and 1st Aviation Brigade surgeon, had provided primary impetus to the improvement of items of safety equipment, reported the results of a survey done on this helmet. Later attempts at modifying it were largely unsuccessful, and until 1969, aircrews were wearing a mixture of APH-5 and AFH-1 helmets.

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In 1969, a new flight helmet, the SPH-4, incorporating markedly improved retention and noise attenuation qualities, was procured for use in Vietnam and received immediate acceptance in the field. It proved effective in the prevention of injuries and became Standard A early in 1970.