subjects fed a vitamin A-restricted diet. Currently, the ready availability of daily vitamin supplements and the general level of nutrition of the population as a whole have tended to virtually eliminate any concern about a lack of vitamin C on the health of skin, gums, and capillary system or a degradation in the pilot's nervous system, appetite, or carbohydrate metabolism due to a deficiency in the B vitamin complex. However, the intrinsic nature of airline operations inevitably results in some irregularity in the eating habits of the commercial pilot. Extended periods without eating can result in low blood sugar (hypoglycemia). Although the effects of long-term diet deficiency are generally agreed on (marked reduction in endurance and a correspondingly smaller degradation of physical strength), the exact relationship between immediate blood sugar level and performance is less well established. Keys ( 1946) demonstrated that reaction time was degraded at blood sugar levels below 65-70 mg%.
The importance of each and every one of the variables described in this section is sufficient that all are the subjects of book chapters and, in many cases, entire texts in their own right. The best that can be hoped is that the foregoing will create a sensitivity to the complexity of the topic field of pilot performance. There is much work that remains to be done in developing more objective methods for measuring the essential components of piloting skill. Even more challenging is the pressing need to define and quantify the cognitive components of the concept of pilot workload. Because of the economic and safety implications of aging on both the airline industry and the pilot ranks, the issue of aging will remain a major topic of interest and concern. Because age does not seem to be a prime determinant of sudden in-flight incapacitation, additional effort is clearly needed to determine the physical factors that can be effective in predicting such occurrences. We already know enough to be certain of the negative impacts of alcohol, smoking, and controlled substances on pilot performance. In short, it is unfortunately clear that, although pilot performance is unquestionably the most critical element in flight safety, it is the aircraft system area about which we know far less than we should.
Atsumi B., Sigura S., & Kimura K. ( 1993). Evaluation of mental workload in vehicle driving by analysis of heart rate variability. Proceedings of the Human Factors and Ergonomics Society 37th Annual Meeting, 1, 574-578.
Ayoub M. M. ( 1969). Performance and recovery under prolonged vibration. Unpublished manuscript, School of Engineering, Texas Technological College, Lubbock, TX.