VAI Spotlight on Safety: Got a Flight? Don’t Skimp on Water and Food! Nutrition is key to human performance. Get plenty of water and healthy food to ensure that you operate safely. It was early afternoon and my colleague and I had been working out of a dimly lit control room for the past five hours researching the effects of food and liquid consumption on pilot performance. On the other side of the wall, our study participant had been at the controls of a flight simulator since 8:30 am and was flying the approach on his fourth leg of the trip. On this sim ride, there are no system failures, no challenging “to minimums” approaches, and no need to run an emergency checklist. But don’t be fooled—this wasn’t just a video game sim session—our pilot hadn’t had substantial food in nearly 15 hours. As the clock neared 2:00 pm, from our vantage point in the control room we knew what was likely to start happening: errors. By this point in our research, we’d run several participants through this experiment. As the effects of low blood glucose and fatigue began to set in, you could almost set your watch to when our pilot’s performance would decline. Most of the errors were minor: air traffic control instructions were missed, headings drifted, and reaction times slowed. By themselves, these lapses and mistakes might be innocuous, but the more interesting aspect of our pilot’s now sliding performance was his lack of awareness. Lessons Learned The aforementioned research was conducted in 2009–10 after my then-company, Decision Research, had been hired to look into how low blood glucose levels would affect pilot performance. Our scenarios consisted of two sessions, one in which the participant would have to fast for at least seven hours and a second session in which normal meals were allowed. Both participants would then fly the sim for the majority of a day, with breaks between flight legs where flight planning was required (this was before ForeFlight). It’s important to note that this wasn’t a study about diabetes or hypoglycemia; our study pilots had no dietary or other ailments that would affect their performance. Based on the results of our research, two key lessons emerged: first, low (but still within the normal range) blood glucose levels can trigger cognitive performance issues or declines. Second, and perhaps most important, cognitive performance may be affected for quite a while before the individual notices the decline (if they notice). The degree of decline can vary across people. In our study, most of our subjects were very good at rationalizing errors they caught during the sim session and were unlikely to attribute their mistakes to a lack of food. Lastly, it takes several minutes to recover from low blood glucose: your brain won’t immediately be in tip-top condition after you eat an energy bar, so give yourself 20 minutes. Your Brain on Insufficient Glucose To summarize the neuroscience briefly, the human brain is a huge consumer of energy and relies heavily on glucose as its primary energy source. And perhaps as a design flaw, our brains don’t store glucose; instead, they rely on a continuous supply of it. As a result, disruptions to the amount of glucose we take in will begin to affect some of our brain functions. Similar to the effects of fatigue, low glucose levels begin to chip away at our brain’s executive control abilities; functions of attention, vigilance, inhibition, and performance monitoring begin a subtle slide downward as conditions continue. In aviation (or other performance-critical roles), performance monitoring is an essential skill our brains undertake, and among the numerous other human-performance and human-factors topics, we probably don’t spend enough time talking about it. Maintaining situational awareness and the ability to monitor feedback from our actions within our operating environment is a labor-intensive operation for our brains. In scenarios in which we have back-to-back flights or short legs or high-workload legs, operating in field locations might put us at risk for reduced brain function when we’re unable to keep up with food intake given the demands. In addition to the go-to pilot’s tool the IMSAFE checklist (see graphic, left), a good safety go-to is the Swiss Cheese model, in which weaknesses in an organization’s safety procedures are likened to the holes in slices of Swiss cheese in terms of their variation in size and placement—and potential alignment such that hazards can pass through the holes, leading to an accident. While having low blood sugar alone might not lead to a poor flight outcome, it would certainly be another hole in the cheese that could put us in a situation in which we don’t want to be. Jeff Currin is a safety standards analyst for Global Medical Response’s air medical operators. He has been a fixed-wing pilot for 20 years. For more on nutrition and cognitive performance, see the sources consulted in writing this article: • “The Effects of Blood Glucose Levels on Cognitive Performance: A Review of the Literature,” a US National Aeronautics and Space Administration technical memorandum, 2007 • “Diabetes and the Brain,” by Amar Singh, 2023 • “Effect of Hypoglycemic Events on Cognitive Function in Individuals with Type 2 Diabetes Mellitus: A Dose–Response Meta-Analysis,” Frontiers in Neurology, August 2024.
