An aviation medicine 'Dear Doctor'. Dr. Dougal Watson.
From the August 1996 issue of the AOPA (Australia) magazine.
This month Flyin' the ointment considers a member's question concerning injuries that might result from aerobatic flight.
AEROBATICS - "THE IRRESISTIBLE CHALLENGE".
Thank you for your very informative Flyin' the Ointment articles in the AOPA.
Two years ago I discovered a new dimension to flying - aerobatics. The challenge is irresistible to learn new manoeuvres and to perfect them, however the fly in the ointment is, I am sixty one years of age. The average G range for most flights would be +4.5 to -0.5.
My question is, even though I feel very fit and hold a class I medical, my uninformed imagination pictures critical organs in my body being dragged from their usual comfortable positions and possibly, over a period of time suffering damage as a result. It doesn't do much for your sagging face (I am female). How ever an in-flight failure there (your face) will only have the plastic surgeon rubbing his hands but what about the other seemingly "loosely fitting" important parts, heart, brain, lungs, liver, etc. being forced from their resting place frequently makes me wonder what may be the result?
I would appreciate your views as there possibly are other pilots who also have given it thought along with any other health hazards associated with regular but not extreme G-loads.
Isn't aerobatics just such a wonderful way to spend time aloft? It's great fun and helps keep so many important flying skills honed to a pretty fine edge. The summary of what I'm about to write is "Keep flying those aeros and don't worry too much about the loose bits being nudged where they don't want to go". Let's look at the situation in a little more depth. I'll try to limit my discussion to aerobatic manoeuvres at the novice/sportsperson categories, with a G loading of -1.0 to +5.0, which seems to be where you are flying. Maybe we'll talk about advanced, unlimited, aeros another day when I eventually manage a Porteus Loop or a Lomcevac.
Aerobatics exposes its practitioners to a number of potential aviation medical risks. These include disorientation during flight, motion sickness, fatigue, and the direct effects of the G on the body.
Disorientation.
Disorientation does not appear to be a big problem during most aerobatic flight. This is probably because we tend to fly aeros in high quality VMC, during daylight hours, and with lots of altitude below us for recovery from mistakes. We also tend to fly our aeros 'outside' the aircraft with only occasional instrument checks to confirm altitude, attitude, engine performance, G-load etc.
Disorientation is potentially a greater problem for low level aerobatic pilots but this doesn't usually include the novice /Sportsperson aerobat. Aerobatic flight at night is hugely disorienting (although it can be hauntingly beautiful hanging inverted in your straps looking down through your transparency to the starlike city lights below) but this is also not regularly practised.
Airsickness.
Aerobatic flight is probably the most likely type of flying to cause airsickness in those susceptible individuals. Even the most seasoned aerobatic pilot can get some airsickness problems after returning from a week or two of holidays.
There is no simple cure for airsickness. Some medications can be of short term benefit but their usage, while you're pilot in control of aerobatic flight, is of limited application and you should consult your DAME beforehand. The best approach to airsickness, in aerobatic flight, is to gradually acclimatise yourself to the sensations by limiting your initial exposures and gradually, over the weeks, work up your exposure. Having said that there are some folk who are very sensitive to airsickness and will never adjust fully. They would probably be best advised to avoid aerobatic flight.
Even mild airsickness can be quite dangerous during aerobatic flight. Mild airsickness is quite capable of distracting you from the all-important job of flying and also causes you to fatigue more rapidly. Either of these can lead to less safe aerobatic flight.
Fatigue.
Aerobatics is hard work. Even the most experienced aerobatic pilots are fatigued after their performances. A thirty minute aerobatic sortie is considerably more tiring than, say, thirty minutes of circuits. A fatigued, tired, pilot is a potentially dangerous pilot - especially when manoeuvring an aircraft in such extreme attitudes. A fatigued pilot will also be more likely to suffer G-induced Loss of Consciousness (see below).
Effects of increased gravity (G).
The exaggerated gravity, or 'G', effects of aerobatic flight have a number of effects on your body. The most immediately obvious is that everything is heavier (or lighter during negative G) than you're used to. While under G your movements, especially of free limbs and your head, can be quite uncoordinated because of the increased / decreased weight. As mentioned in the letter your face, and other parts of your body, sag under increased positive G. While increased G makes everyone look older, due to the sagging of facial tissues, I'm not aware of any relationship between aerobatics and premature wrinkles.
Similarly I am unaware of any reported internal organ damage due to the increased G of aerobatic flight. This is possibly because the organs are generally supported by external structures and one another and, so, cannot move very far from their normal situation.
The main concern here is that the blood is not supported and can move, quite freely, under increased or decreased G. High levels of positive G will cause the blood to move towards and pool in the legs while high levels of negative G cause it to move towards the head.
As positive G forces it towards the legs less and less blood reaches the brain. Eventually, if there is adequate G, the brain ceases to function - not enough blood means not enough oxygen. This leads to unconsciousness and is called G-LOC (Gee lock) for G induced Loss Of Consciousness. Less G forces can lead to loss of vision without the loss of consciousness, 'blackout', or just a dimming of vision, 'greyout'. G-LOC can occur at relatively low G levels in some people, especially if they are not prepared for the G. G levels above +3G can be associated with G-LOC although it isn't very common until you get to +4G to +6G levels.
High negative G loads can cause another visual disturbance called 'redout. Some feel the redding-out of the vision is due to the lower eyelid being pulled up over the eye by the increased G although I don't think anyone knows for sure.
High G levels, positive and negative, can also cause some of the smaller blood vessels to rupture. This can lead to small bruise-like marks on the face and shoulder area (negative G) or the legs and buttocks (positive G). Bleeding into the whites of the eyes can also occur with negative G.
In conclusion.
Despite being tiring, disorienting, motion sickness inducing, and exposing its participants to high G loads aerobatic flying is generally safe and a lot of fun. One of the main medical concerns is G induced loss of consciousness which occurs when the positive G load exceeds the individual's tolerance. Bruising of the skin and eyes can also occur from high G loads.
Aerobatics is not, to the best of my knowledge, related to premature wrinkling or the displacement / damage of vital internal organs.
