members may not be aware that they are reaching dangerous levels of overheating, dehydration, physical exertion, stress, fatigue, or sleep deprivation. They could develop performance-degrading problems unbeknownst to their team leaders, particularly if they are fully encapsulated in chemical protective suits, are flying aircraft, or are operating in a remote location. An alert or warning signal to the individual and to his or her squad leader could permit prompt intervention to alleviate the physiological danger and potentially save a mission.

The present-day U.S. military must be able to rapidly deploy around the globe on short notice and be capable of sustaining operations for long periods of time. In order to accomplish these objectives, a variety of occupational specialties are required. Ground combat military personnel have unique roles in combat operations and work in very different environments in order to achieve objectives in a coordinated fashion. Although a thorough discussion of the challenges faced by each group of combat service members is beyond the scope of this report, the reader can gain a small appreciation for the diversity by considering the problems faced by some Army ground personnel as opposed to those faced by some pilots.

The ground personnel’s tasks often include a high level of physical energy expenditure in the face of constant and immediate threats from the environment, as well as from a wide range of enemy activities. Infantry personnel are constantly on the move, either walking, running, climbing, or at times, even swimming from one point to another. These activities are made more strenuous because of the need to carry heavy backpacks, weapons, and ammunition in all types of weather and across all types of terrain. Fatigue is a constant companion because of the physical workload, the environment, and the sleep deprivation that results from limited sleep opportunities and poor sleep environments. Air conditioning, hot water, and “normal” food are nonexistent for combat service members who often work long hours in the worst of circumstances.

The pilot’s task is generally much less physically demanding than what is faced by infantry personnel, but his or her job presents challenges from other characteristics. Helicopter pilots must remain cognitively alert at all times if they are to successfully pilot their aircraft at speeds of 50 to 100 mph while maintaining altitudes of only 50 ft above terrain obstacles. Flying close combat support means that helicopter pilots are operating under conditions that are quite similar to those faced by combat military personnel on the ground: they are close to enemy threats, they are often hot or cold due to the lack of air conditioning, and they are required to live in the most austere and uncomfortable environments for days, weeks, or months at a time. Unlike their infantry comrades, they take off and land several times a day in stressful, low-visibility conditions and try to sleep during short intervals between flights, often in poor conditions. In addition, they are responsible for multimillion-dollar aircraft and the crews on board.

Air Force fighter pilots face different, but often equally challenging circumstances. For instance, F-117 pilots have been known to fly for 18 straight hours in a single-pilot aircraft, strapped into an ejection seat while wearing bulky, hot, protective gear. During this time, they must remain fully alert and fully prepared



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