Keep your sunny side up!
We were sitting at a funky Japanese restaurant sharing an order of edamame, when my friend looked across the table and said, “What’s spatial disorientation?”
I nearly choked on my steamed pea pod.
Somewhere in between did you enjoy Adele’s concert in New York and when is your next 10K race, my friend slipped in an “av-bomb.” (a technical aviation question)
“Why the sudden interest?” I asked.
“The anniversary of JFK Jr.’s plane crash is coming up and I saw a quick blurb about the accident. The NTSB cited the cause of the crash–pilot error, as a result of spatial disorientation.”
After swallowing a swig of water, I opted for the short answer. “When a pilot’s perception of direction doesn’t agree with reality, they’re disorientated.”
She flashed a raised eyebrow and retreated back into comfort conversation.
“Wait a minute,” I interrupted. “Are you seriously interested in the full report?”
She slowly sipped her iced tea. “How about the laymen’s version?”
“Okay, I’ll do my best to keep close to the willows.”
I slid my chair closer to the table and leaned on my elbows. “Spatial disorientation can be caused by disturbances in the vestibular system, a sensory network that provides major contributions to movement and sense of balance…”
My friend hurled her napkin at me.
“Alright, alright, here’s the simple answer.”
When an aircraft flies into poor weather conditions—low visibility due to clouds, fog, haze (not purple of course), the pilot can’t see a distinct horizon or often times anything at all. Without a clear visual reference, the pilot’s sensory systems don’t have accurate information to maintain equilibrium. Without the ability to sense up from down, pilots can have a difficult time flying straight-and-level. (the passenger preferred flight configuration)
The sensory systems affected in flying are your eyes, vestibular (fancy name for the organs in your inner ear) and the nerves in your skin, muscles and joints. (called somatosensory for the science crowd)
Since our eyes are the most reliable, ninety percent of the information we use for orientation comes from our visual field. (kind of makes you want to get your prescription re-checked) If the brain receives conflicting sensations from the sensory systems, the eyes become the final authority.
But as you know, being the most influential doesn’t always make you accurate. Eyes can fall prey to illusions and misinterpretations.
The vestibular system is our body’s secondary orientation mechanism containing motion and gravity sensing organs.
We have a system in each inner ear capable of giving the brain enough information to maintain balance. (an anatomical design perk since pilots live for redundancy)
Each semicircular canal has three perpendicular tubes filled with fluid and sensory hairs—fine and wispy, like you’d find on a fair-haired women’s forearms.
As the body moves, the fluid shifts and sends a signal to the brain saying turn, pitch or yaw.
On the ground, the vestibular system can even replace the inputs for the eyes. Consider this; even if you close your eyes you still posses the balance to walk around.
In flight, things are different. When a pilot initiates a turn in the air, the inertia of the fluid in the ear canals moves in the opposite direction to the fine hairs and sends a message to the brain confirming an attitude change. But if the turn continues for a period of time, the fluid in the canal catches up with the hairs (reaches equilibrium in the ear canal) and fires a message to the brain saying the turn has stopped.
The airplane, however, is still turning even though you sense level flight.
And when the pilot finally stops turning, the fluid shifts again (from neutral) creating a sensation of turning in the opposite direction. The plane is actually level and your body is telling your brain that it’s still in a turn.
Have you ever pulled in to a parking space while the person next to you is backing out and slammed on your brake pedal thinking your car was the one moving? That is the sensation pilot’s feel in this scenario.
The last system comprised of nerves, muscles, joints and internal organs senses pressure differentials, allowing pilots to feel the g-forces as their body reacts to the motion of the aircraft. This sensation is mostly felt where body touches aircraft–your backside on the seat.
So how do pilots keep themselves orientated?
Training, continuous training. The Gat II simulator has programs to allow pilots to practice, identify and recover from these in-flight scenarios.
The Vertigon, like the one Clint Eastwood and James Garner rode in “Space Cowboys”, uses a rotating seat mounted on gimbals that spins in a way to simulate the pit-falls of our sensory systems. (just a tip–if you try the Vertigon, maybe at a theme park or air show, you may want skip the dairy products for a few hours before your ride)
The final and most important deterrent to becoming disorientated in an airplane is the pilot’s reliance on their instruments. The methodical discipline of instrument training can be the sensory systems greatest ally.
“So did JFK Jr. have instrument training?” My friend asked.
“I’m sure he did. But proficiency in marginal and instrument flight conditions requires continuous hours of committed practice. Experience, especially for newer pilots, is the only way to overcome the physiological effects of spatial disorientation.”