Are you fit for combat? – nausea during high-velocity flight
David A. Hagginbothom
For those of us who have endured a G-induced Loss of Consciousness (GLOC), the experience might be described by the title of the Steppenwolf “classic” rock song, Magic Carpet Ride. One moment you are going about your business in a hard turn, and then, before you have your next coherent thought, “magically” almost 30 seconds of your life have vanished. What was different about this hard turn from all of the rest you have pulled before and after, you really have no idea. But now you know one thing for sure, your body and brain have finite limitations. And for reasons that can only be described as a mystery, your ability to tolerate Gs comes and goes even though the circumstances seem to be virtually identical.
While GLOC is a lot less critical to a bomber puke like myself when flying a heavy, it’s a subject near and dear to every high-performance fighter pilot and to those involved in training new pilots as well. Having just flown the T-37 as an Instructor Pilot (IP) at Sheppard AFB, Texas, I have a couple of thoughts that apply to flying fighters and trainers.
My first personal experience with GLOC came on my first advanced contact ride in Undergraduate Pilot Training (UPT) as a T-37 student pilot at Williams AFB, Ariz. It happened on my first split-S, being demo’ed by my IP. We met power and airspeed entry parameters, raised the nose, rolled inverted, and started to pull. I was faithfully trying to squeeze the imaginary beach ball between my knees like I’d been taught in academics. To keep the nose tracking in a straight line, the IP said to look up for the horizon. As I focused my attention on obeying this instruction, I ceased concentrating on my anti-G strain effort. I remembered the nose of the jet being 90 degrees nose low, but the next sight picture I recall was wings level on the horizon. This was a rather disconcerting realization, albeit better than if I was still screaming directly at the ground.
Fifteen years after UPT, I experienced my second “magical” experience with GLOC.
I had just recently completed Pilot Instructor Training, when Air Education & Training Command decided to send all its new IPs through the centrifuge at Brooks AFB, Texas. I’d been flying the line, double-turning most days and occasionally “trip-turning” to meet all my continuation training requirements. One-go days were rare, and the schedule didn’t leave much time to hit the gym for a workout. At 38 years-old, 6 foot 2 inches, and 180 pounds, I am not what you would call a natural “G machine,” but still this was not going to be my first experience with Gs, and I thought I was ready.
But sure enough, during the 6.5 G run, I experienced what the centrifuge instructor mercifully deemed to be “significant” light loss (meaning total, from my recollection). The 20-something aged fellow IPs asked me what it was like. When I told them I remembered hearing loud rock music, they said I must have had a flashback to the “Born to Be Wild” 1960s. For me it was a flashback to UPT and the relearning of the lesson that our bodies and brains have finite limitations — a lesson applicable across all aviation communities. I also relearned that the best defense is a good offense, through the timely and properly executed Anti-G Straining Maneuver (AGSM). About an hour later, after a thorough debrief and re-education, I passed — versus passing out — without too much difficulty.
Over the years we’ve discovered several layers of defense against GLOCs. Consult your friendly neighborhood aviation physiologist or flight surgeon for the latest AGSM approved techniques. To maximize the effectiveness of your AGSM, you also need to be in top physical shape. Dedicated, self-disciplined visits to the gym, multiple times a week, are required to attain and maintain both bulk muscle strength and aerobic/anaerobic endurance as you get older.
Proper fitting, pre-flight, and wear of your anti-G suit is another defense that may come to mind. However, basic ensembles offer little more than one extra G capability. Advanced systems offer better protection, but there’s the old adage “you can’t squeeze blood from a turnip.”
Adequate hydration is a key to success since dehydration leads to overall reduction in blood volume and, by virtue of the first law of thermodynamics, lower blood pressure. So drink the right kind of fluids on a regular basis.
Fulfilling a variation of Sun Tzu’s basic military dictum to “know yourself” can also be a great asset. Take your immediate state of health into account because sickness and fatigue can significantly affect your G tolerance. Also, some body shapes/types offer an inherent or “natural” ability to better tolerate G forces. Short and stocky usually prevails over tall and thin, and knowing your own resting G tolerance (remember the slow G onset profile in the centrifuge?) will help you to focus on how hard you need to strain.
Performing G “warm-up” maneuvers allows self-assessment of day-to-day physiological G tolerance and a test of your equipment. Pilots should realize that this limit is subject to minute-by-minute or even second-by-second cognitive impacts like distraction or prioritization. The limit may also decrease as the mission progresses due to physical tiring. The last engagement is the time of greatest risk for GLOC.
Finally, recognizing that survival in a high G environment is more in your head than anything else is vital. Dr. “Geff” McCarthy, Col, USAF, Ret., an aviation physiologist and psychologist believed in the philosophy: “You cannot max strain and max think simultaneously.” In flight, when the “fights on” you are concurrently maneuvering, working the radar, employing weapons, and keeping the visual and tally on wingmen and bandits. The more you need to think about flying, the less you may be able to concentrate on your G strain. Training and experience will allow you to do both, but eventually everyone may become task saturated and mis-prioritization may occur. So keep your head in the game.
What’s the moral of the story? You have a limit, everyone does, and each year GLOC kills pilots and destroys aircraft as a result. It’s imperative to stay ahead of the Gs even before you step to fly, because once you’re behind you won’t catch up until you let off the back stick pressure. Be prepared and try to remember to do all your “max thinking” before you have to do your “max straining” as you keep’em flying safely!
COPYRIGHT 2002 U.S. Department of the Air Force
COPYRIGHT 2004 Gale Group