How spatial disorientation can trap pilots

A pilot must learn, under actual threat of death, that it is impossible to maintain an airplane in controlled flight without visual reference to the horizon, even if that horizon is an artificial one.

Loss of control accidents caused by spatial disorientation continue to regularly claim the lives of pilots and passengers in spite of required training and the best efforts of instructors to instill the importance of non-instrument rated pilots recognizing and avoiding instrument flying conditions.

Runway lights at night
Black hole approaches can easily lead to spatial disorientation.

There are many ordinary circumstances in flying that can result in a pilot inadvertently encountering instrument flying conditions where there is no effective natural horizon:

  • Flying over water on a clear moonless night can easily result in disorientation, intense vertigo, and a loss of control.
  • Flying under the same conditions over land in sparsely populated areas has the same effect.
  • Flying on top of a horizon-to-horizon seemingly flat deck of solid cloud that is not aligned with respect to the real (invisible) horizon below, can be disconcerting to the point of serious nausea and worse.
  • Clouds are easy to inadvertently enter when flying at night, even over a large city.
  • In addition to acting alone, haze, smoke, and fog exacerbate the above conditions.

It is almost impossible to imagine the difficulty or impossibility of controlling an airplane under these seemingly ordinary circumstances without actually experiencing the conditions. It’s not stubbornness or lack of training that causes the continuing occurrence of this type of accident; it’s our anatomy that confronts a pilot with often insurmountable problems.

We maintain the position of our head in space using a combination of sensory inputs, obviously including vision, but less obvious and equally important are the effects of gravity and inertia on our muscles and on the fluid in the semi-circular canals in our inner ears. Even so, most of us can walk, swim or run with our eyes closed.

Speaking of the inner ear, we have three semi-circular canals (tubes, really) partially filled with fluid, in each ear. There is one tube in each of our ears for the three dimensions of angular rotation that we must learn to contend with when learning to walk:

  • The pitch axis – head tilt forward and back (nose up or down in an aircraft, controlled by the elevator).
  • The roll axis – head tilt left and right (wings banked, controlled by the ailerons, if you are in flight).
  • The yaw or vertical axis – think figure skater in a spin (controlled by the rudder pedals in an aircraft).

That last one is not always as useful as the other two axes in controlling an aircraft, but it is still critically important, as it is good at adding to the confusion that often results in disorientation and vertigo.

Our brain processes these hundreds, if not thousands, of simultaneous sensory inputs and directs the rest of the body to position the head accordingly.

Inner ear diagram
The system works really well… until it doesn’t.

By the time we decide to learn to fly, the portion of our brain which is responsible for balance and spatial orientation – our position in space – is thoroughly convinced that it knows best. It is more than a little difficult to convince it that it still has more to learn, despite the fact that the logical portion of the brain has been studying, and is insisting otherwise.

If we allow it, its survival instincts are strong enough to kill us.

Centrifugal, centripetal and inertial forces in flight mimic the effects of gravity and, in combination with the actual effects of gravity, just confuse the hell out of the brain. Without sufficient study, re-training, practice and experience, it reacts, often inappropriately, when it becomes disoriented.

I observed all this in action with my buddy Max.

My student Max, like many before and after him, could just not bring himself to believe that he could not fly the airplane by the seat of his pants without visual references outside the cockpit in spite of instruction and all the materials he had read about spatial disorientation and vertigo.

One evening we flew to a grass strip about fifty miles south of the city in the middle of sparsely populated farm country, where an old Piper Cub was being restored in the proverbial barn. We had a great time hangar flying with the owner and when it was finally time to leave and actually go flying, it was pitch black outside. It was a beautiful night, perfectly clear, no moon – you could see a hundred miles if you were high enough.

Max was shocked. “There are no runway lights, what do we do now?” He had never been allowed to use the “landing light” during night flights at our lighted home field – that’s another story – but I explained that it was actually not a bad takeoff light. “We’ll just taxi the length of the runway to make sure there are no deer eating it, and it’ll be just like driving your car,” I told him.“Cool,” said Max.

Max took off and we began to climb. A couple of hundred feet from the ground, I asked how he liked flying from a grass strip. He was having a ball. Not long thereafter Max, the airplane, and I were in a ten-degree bank to the left. “How are we doing Max?” Max was ecstatic. This was fun! At 400 feet, and now in a 30-degree bank, I asked how the attitude indicator looked. It must have looked a little funny, because Max allowed that it must be “a little off.” At around 600 feet, we had pretty much stopped climbing, and the attitude indicator was telling us that we were in a sixty-degree bank. Max was perplexed, but insisted that the instrument must be failing. He was finding it difficult to believe that we were anything but wings level.

When we were well past ninety degrees of bank, I said to Max “I have the airplane” and, as he had been trained to do, he immediately removed his left hand from the control wheel, his right hand from the throttle, and pulled his feet well back from the rudder pedals, positively relinquishing control of the airplane to me. No big deal, just routine until I rolled the airplane back to wings level. His reaction was involuntary and violent as he crashed into the pilot’s door as the recalcitrant portion of his brain fought to remain “upright.”

Given the subdued light in the cockpit, and our less than perfect visual night adaptation, there were just enough bright stars in the sky to match the scattered barn lights on the ground. There was no visible horizon on that beautiful, clear night.

Max became a true believer at that point and at last check, he was still alive and flying.

9 Comments

  • Spatial disorientation was blamed for the JFK Jr. crash. I disputed this, based partly on the 56 sec. of level, controlled flight during the descent. I put the question as to how many pilots had ever experienced spatial disorientation (as I did early in my career) in the AvWeb Question of the Week, and the answer came back an astounding 80%. All pilots should train to handle this threat early in their flight training.

  • This happened to me in broad daylight. I was doing some circuits out of Larnaca and it was summer and very hazy. On the downwind leg abeam the tower ATC instructed me to orbit, and so I established the requisite bank attitude and turned out over the sea, and immediately lost my horizon in the haze. No problem, but then I felt that I was still flying straight and level, so I applied some more bank to ‘restore’ the turn, and it was only when I glanced at the artificial horizon that I found that I was banked at more than 45 degrees and descending. It took quite some concentration for me to consciously level off and then follow the instruments. When I restored the turn and came in sight of the ground horizon again the illusion vanished as quickly as it had come. And this was within a few seconds and in broad daylight! A VERY salutary lesson indeed!

  • I was kind of curious as to what plane was being flown allowing a student to surpass 90° of bank. However, that is not the purpose of my comment. I had flown solo at night to KPVD once and upon take off to return to KFRG I had felt what I believed to be carbon monoxide poisoning. I immediately opened the small window and began scanning instruments. After the flight I thought long and hard about it and realized it was spacial disorientation. The take off from a lighted environment immediately into a dark lightless environment had nearly gotten me.

  • Similarly to Adrian I was flying across Australia at one point over hills i inadvertently flew into low clouds I notified atc and was assured there was no ifr traffic and flew by instruments until I knew by time that I was straight and level and past the hills so could drop below the clouds no problem then one day later returning to my home airfield in late summer I had to turn to align with the approach path and almost immediately the haze made me lose my orientation. Quite distressing until I leveled again and found the horizon. That was my first time for disorientation flying by myself. Safe to say I was very very careful the rest of that flight about turns and my horizon. It was surreal.

  • My moment was in serious haze from all the wildfires out west, just a couple of months ago. The haze was so thick I almost lost reference to the ground. I was unable to rise above the haze in my C172, and because this is out west, I couldn’t get low due to ever changing terrain. I was banking left about 15-20 degrees and would have sworn that was straight and level. I decided to turn back to the airport I had departed, but that was into the rising morning sun and was even worse. Fortunately, I gathered my wits and realized that the instruments were absolutely correct during what became a 360 degree standard rate turn. Back on my planned course, I let go of the controls to get true straight and level (I know that in calm air my airplane will fly itself) and everything was good. Stayed on the course line on my iPad, and the smoke and haze gradually got lighter over the remaining 2 hours.
    I have recently purchased a Diamond DA40 with G1000, and plan to pursue the instrument rating I never got around to in the old C172N.

  • I had a similar disorientation experience in day / instrument conditions. The artificial horizon was showing me in a banked turn, but I felt I was straight and level. We call it ‘The Leans’ and it’s very disorientating.

    Thankfully I remembered a piece I’d seen in a magazine about recovering from the leans by shaking your head for a couple of seconds. It shakes up the tubes in the inner ear and does a sort of reset. It worked instantly for me and I was back in sync with my artificial horizon.

  • During instrument training with the hood on, I spent almost the entire flight feeling as if I were turning left while flying straight and level. At first I was surprised the instructor was not commenting on the steep banked descending turn, but the instruments, and as a result, my attitude, altitude and direction, were right where they were supposed to be. Great lesson learned that day!

  • I was the copilot on a B-52 bomber in the days of the 24-hour airborne alert in the early ’60s. We had taken off from our base in south Georgia and headed north for the polar regions and the next 22 or so hours. Not long after level off we realized that we had a serious problem with the autopilot, which wouldn’t engage. After an hour of consultation with our maintenance people, plus the autopilot manufacturer, if was determined that it had died, and nothing would bring it back to life. We promptly asked for permission to abort the mission. (We were just two pilots, with no relief.) Permission denied. So we hand-flew the beast north into the blackest night I have ever seen. We then encountered a display of Aurora Borealis that just about did us in. It was a beautiful flat display that was canted about 30 degrees to the true horizon. I have never encountered such vertigo, before or since, nor had the aircraft commander. We took turns hand-flying the airplane, each of us could last about 15 minutes until the vertigo overtook us and we would have to trade off. The phenomenon lasted almost two hours, and no sooner had it disappeared than we were faced with the first of two heavyweight inflight refueling. When we finally completed the mission and landed, they nearly had to carry us off the airplane. That was the worst I had ever encountered.

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