Stick and Rudder

So there was the novice pilot who told his teacher, “I think there’s something wrong with that funny instrument on my panel....the little ball isn’t moving,” and of course the riposte, “Congratulations, you just made a coordinated turn!” 

We know that if you don’t work stick and rudder in unison, efficiency – as well as elegance and pride – is eroded. Many other aircraft systems also “speak” to one another, and a problem in one place can have knock-on effects, sometimes with grim sequelae. A spider’s web blocking a pitot tube, the autopilot hunting for altitude degrading airspeed, a loose body blocking a control wire in its tunnel.

It should come as no surprise that the human body is similarly interconnected, and I thought it would be fun to explore some of these systems, primarily to alert my fellow aviators to how one symptom can imply something very different from what they are thinking. Additionally, some of this stuff is just plain fascinating!

Aches and Pains

The pain of getting a bill for your annual inspection – it hurts. But the connection for this pain is obvious, the cost of a given component, the price of talented labor. But human pain can be complex. The gallbladder sits under the liver in the upper right side of the abdomen. But when diseased, the pain might be felt in the shoulder tip. Similarly, a diseased spinal disc in the low back may cause hip pain and an arthritic hip may cause knee pain. This is because we experience pain based on how nerves are connected. So your doctor is not crazy if he or she suggests investigating a part of your body distant from where you feel pain.

Coordinated Turns

To continue the aviation theme, what could cause a human to have issues navigating a course? Human coordination is a complex interplay of inputs from eyes, inner ear, special receptors in our muscles and joints that allow proprioception, our sense of where each part of our body is in space; truly our sixth sense. All of these inputs are processed by the brain, so an issue there such as impaired blood supply, any neurological disease or just plain loss of brain cells from age or lifestyle can make you walk like a neophyte pilot flies. Sometimes people experience dizziness from standing up, which can be so severe as to cause collapse. This is usually due to a blood pressure problem, in turn informed by the autonomic nervous system that controls systems we don’t have to think about. One condition called “PoTS” (postural orthostatic tachycardia syndrome) causes the heart to race and blood pressure to drop. PoTS can follow pregnancy, head trauma or a viral illness like Lyme disease, infectious mononucleosis or Covid-19.

In other words, if you are starting to have dizzy spells or experiencing motion sickness as a new symptom, please see your doctor as it could indicate problems with several body systems. And remember, symptoms like this merit self-grounding until all sorted.

Weight and Balance

Whereas a plane that is overladen will have problems making it to the destination, a heavy human will make it to their final destination rather sooner than desired. I have harped on about how extra weight – obesity to any degree – will damage every system in the body and ensure that one is playing a celestial harp sooner, rather than later. But it is not just fat that is a warning sign. If you notice swollen ankles, that one can press with a finger leaving a depression, this is pitting edema, which should be depressing because it can mean many things including liver or heart failure. In the latter, the heart has been damaged, perhaps by vessel disease and as a result cannot pump enough fluid around the body, so it accumulates in dependent parts like the ankles. It can also pool in the lungs causing orthopnea (breathlessness lying flat) and paroxysmal nocturnal dyspnea, which literally means to awake during the night gasping for breath requiring one to sit up. Take these as seriously as you would a misfiring engine in flight.

Another scenario is where one notices continuous thirst, repeated urination and fatigue – these are all classic symptoms of diabetes mellitus or just plain diabetes. The name refers to the fact that the urine is sweet, due to sugar spilling over from the kidneys. What possessed someone to taste urine is beyond me! Again, this is a complex interconnection where failure of the body to produce or react to insulin, a hormone, can have profound consequences such as blindness, kidney failure, heart attacks, stroke and even impotence. That got your attention! There is another disease called diabetes insipidus, where the urine is “insipid” or flavorless; once again, who is tasting all this urine? It is caused either by a number of provocations such as a tumor in areas of the brain called the hypothalamus or pituitary gland or due to a head injury. Another example, albeit very rare, of a problem in one part of the body causing what some might not expect.

Paper or Plastic? Or Aluminum.

When one performs a pre-flight aircraft inspection, subtle indications of underlying problems may be apparent if one is open to seeing them. Fluid on the hangar floor suggesting a leak, a few pieces of dried grass that might hint a bird has built a nest in your engine compartment. It is obvious to pilots how a highly inflammable avian habitation could bring an aviator to a fiery end. Likewise, it can be obvious to physicians when we see skin changes. A new rash can communicate to an astute doctor that there is inflammation in the bowel or joints, that there is a systemic infection or cancer. Just as you would report anything new and odd to your mechanic, tell your doctor if you see changes.

Exhaust Gas

An improperly tuned engine or incorrect fuel flow management will change what comes out the exhaust, a critical factor in flight efficiency. Recently I learned about another fascinating concept – many patients who acquire a respiratory infection complain that they are having to get up at night to urinate with greater frequency. I had put this down to the fact that when one is sick, we are encouraged to drink more fluids. But there is another possible explanation. Having difficulty breathing might inspire one to mouth breathe; the pun is deliberate. This causes us to “blow off” more carbon dioxide from our lungs, thereby changing body chemistry, making the blood less acidic, a condition we call respiratory alkalosis. The body endeavors to correct this by constricting smooth muscle in our airways to limit how much carbon dioxide is lost, but smooth muscle in the bladder reacts as well and we experience this as a desire to vent some urine. So getting gas management is just as important for people as it is for aircraft!

I have spent decades in medicine and each new snippet of medical information I learn delights me. The human body is a complex and wonderful machine and should be properly maintained. I remember when I started flying being encouraged to spend time at the mechanics shop to see inside the aircraft as much as possible, that it would help me to understand what a given noise or sensation might mean. The body is the same, and while I am not suggesting you attend your nearest OR to get a peek inside the abdomen, head or chest, please do keep an eye on your body.

Fly safe, fly well.

You can send your questions and comments to Dr. Sackier via email: [email protected] and listen to his weekly podcasts at:

Jonathan Sackier
Dr. Jonathan Sackier is an expert in aviation medical concerns and helps members with their needs through AOPA Pilot Protection Services.

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