Preventing spacial disorientation

A version of this story was first published here.

It was 9:45 on a clear, moonless night when I lifted off from the small airport in Western North Carolina, leaving all lights behind. Along with the lights went any reference to the world around me. As I ascended, I searched for a horizontal landmark. Lights on the horizon. A road. River. Anything. The mountainous terrain and the night left me with nothing to see. 

“If you lose sight of the horizon, look down at the instruments, they will tell you the truth” my instructor always said in training. Right! But by the time I Iooked down at my instruments I was already in a 20 degree left hand turn.

In 3 to 4 seconds my body had betrayed me. I had no sense of the airplane turning. It was gradual and unnoticed.

Thankfully my training took over to prevent what could have been a simple but devastating problem.  Had I been tired or complacent, my fun night flight of only 6 miles to another airport in town could have ended differently.

The thing is, while my instruments were correct and directly in my line of vision, and modern training does stress trusting those instruments. But there is something else and a much more difficult thing to reconcile: I also had to recognize that the airplane was in fact rolling. A single engine plane has a natural tendency to turn to the left on its own. Not only that, but it happens too slowly for your inner ear to pick up on the change. Left uncorrected, most single engine aircraft will enter into a steep spiral dive. 

Had I been in a different state of mind, had my training been something I just recited instead of studied and believed in, I might have not have noticed in time. If I had a passenger who was talking, or a flock of birds had crossed in front of us, who knows what would have happened.

My own experience is a well documented problem and a solution has long been searched for. I suffered from momentary spatial disorientation. The thing inside us that gives us our sense of direction, my inner ear, was completely deceived by the gyroscopic motions of the airplane. My eyes, which are normally our body’s back up sensors, were not able to tell my brain where the horizon was. In aviation, this is generally considered “not good.”

Spacial disorientation is a mitigatable problem. The attitude indicator in airplanes has been around for almost 100 years and is very capable of telling you what is happening. Of course in order for that instrument to be of any use, you have to remember to look at it, understand what it’s telling you, and believe that it’s telling you the truth. 

Spatial disorientation can happen in all types of aircraft, and to any pilot. One of the most famous of these incidents involved the death of John F Kennedy Jr in 1999. Mr Kennedy took off from Essex county airport in Fairfield, NJ on a flight to Martha’s Vineyard. While we won’t ever know for certain, it’s believed that Kennedy most likely lost sight of the horizon. Some pilots in the area reported some haze over the open water that evening. Conditions like this would make it almost impossible to judge what was sky and what was ocean. The plane slowly entered into a spiral dive and impacted the water, killing Mr Kennedy, his wife Caroline, and his sister, Lauren.

The National Transportation Safety Board (NTSB) launched an investigation and eventually concluded that the crash had been caused by “the pilot’s failure to maintain control of the airplane during a descent over water at night, which was the result of spacial disorientation.”

Spacial disorientation is also a problem for highly experienced pilots. I was sitting with my friend Jerry a few weeks ago as he told me stories of his time as an F-4 Phantom pilot in Vietnam.  He flew 221 combat missions in 1968 and 1969. He told me a chilling story about a flight at the end of one of his missions. He was returning back to base when he and his wingman flew into some clouds and Jerry lost sight of the horizon. Despite being a veteran combat pilot, he didn’t notice his problem until he heard his wingman making repeated calls to him over the radio. 

“Where are you headed, lead?”

At that moment, they broke through the clouds and he pulled up. It was then that Jerry realized he had somehow threaded his way into a narrow valley with high mountains to either side of him, reaching far above his current altitude. He considers this the most dangerous flight of the war for him. Imagine coming back night after night with bullet holes in his fighter and then citing that one time he didn’t know which way was up on a flight home as the thing that almost killed him. His instruments were working. He knew better. And yet it was someone else’s voice on the radio that got him home alive. His story certainly got my attention.

In our cars we enjoy safety options like traction control and anti-lock brakes. In General Aviation, complex systems present both a technical challenge and a complicated regulatory environment, the latter being more hurdle than help.

I’m an engineer and inventor by trade, so in the days following my incident I investigated solutions and put my inventor hat on.

I fly a Diamond DA-20-C1. A single engine 2 seat aircraft with excellent visibility and a great glide ratio. It’s a terrific ride. It was built in 1998 and is relatively new for a General Aviation aircraft. Many of the other planes at our small airport have been flying since the 1970s or earlier. It has a standard set of round gauges similar to most aircraft of this size.  Flight controls are cables directly connected to my hands and feet via pedals and a control stick. The airplane does have electric trim, but that’s the only flight control that could be manipulated directly.

So, for this very typical aircraft in the GA fleet, what do we need to build to solve the spacial disorientation problem? 

The solution is more obvious in a modern fly by wire aircraft with a glass panel display. We’d do some fancy algorithm work with sensors and take advantage of cheap computing power and could design a system much like the traction control in your car. A computer could make decisions much quicker than your brain. We’d just let it nudge the airplane back to a good flight envelope. This isn’t quite as simple as it sounds to actually implement, but it’s not insurmountable. 25 years from now I suspect this will be standard equipment, just like traction control and anti-lock brakes on your car.

On the other hand, there are many thousands upon thousands of perfectly flyable aircraft that fit the description of the Diamond I fly- an older aircraft with directly connected cable flight controls and a mechanical set of instruments whose designs predate WWII. Creating a fix for that platform isn’t so obvious. Planes like this usually don’t have access to automated manipulation of flight controls. Replacing instruments is expensive. In addition many of the instruments you might make changes to are often part of the flight certification of the aircraft itself. Few owners will want to make expensive changes to a system that they perceive to be working just fine.

The quickest solution is most likely a small general purpose secondary informational system that is portable or semi portable. Computing power is constantly getting cheaper and faster. How cheap? I built an ADS-B receiver with bluetooth and a 4 inch touch display for $100 US with off the shelf parts, over one weekend. I could have also done this with a repurposed cell phone.

Just like the portable GPS units you see in older General Aviation aircraft, what if we build a secondary display “for informational purposes and planning.” What do we put on it? How do we grab the pilot’s attention when he is in trouble and doesn’t know it?

Much of my research, as I prototype possible solutions to this problem, concentrates on the display of information to a pilot. First we want him to be aware there is a problem. Then we want to help him do something about it.  If we look back at my own spacial disorientation experience and that of my friend Jerry, however, all of the visual input in the world won’t help if the pilot doesn’t look down at the indicator. The addition of a secondary sensory input is needed. 

“Where are you going, lead?” was a very helpful reminder to Jerry. That works great if you’re a combat pilot with a wingman. We need something automated for everyone else. If we connect this secondary sensor and display system to the intercom of the aircraft, or the mp3 player input of the pilot’s headset, we can set normal flight envelope ranges and notify the pilot with both sight references and a voice that tells us when something is wrong. A red arrow accompanied by the phrase “bank left” would have kept me out of trouble nicely.

A computer suggesting I “Pull up” or “Bank right” is certainly better than a letter to your family that starts “We regret to inform you…”



Posted on August 17, 2015 and filed under Adventure, Learning, Aviation.