The inner ear

Most problems related to disorientation can be traced to the inner ear, a sensory organ about the size of an eraser on a pencil. It may well be the most well-protected organ in the human body, and for good reason. It's the key to our ability to balance when on the ground, or to remain oriented in space when we fly.

The inner ear is similar to a three-axis gyro. It detects movement in the roll, pitch, and yaw axes that pilots know so well. When the sensory outputs of the inner ear are integrated with appropriate visual references and spatial orientation cues from our bodies, there is little chance to experience disorientation.

Vision and the inner ear

The problem occurs when the outside visual input is obscured, and the seat-of-the-pants input is ambiguous. Then, you're down to just the output from the inner ear—and that's when trouble can start.

Fluid in the inner ear reacts only to rate of change, not a sustained change. For example, when you initiate a banking left turn, your inner ear will detect the roll into the turn, but if you hold the turn constant, your inner ear will compensate and rather quickly, although inaccurately, sense that it has returned to level flight.

Sensory illusions

As a result, when you finally level the wings, that new change will cause your inner ear to produce signals that make you believe you're banking to the right. This is the crux of the problem you have when flying without instruments in low visibility weather. Even the best pilots will quickly become disoriented if they attempt to fly without instruments when there are no outside visual references. That's because vision provides the predominant and coordinating sense we rely upon for stability. Perhaps the most treacherous thing under such conditions is that the signals the inner ear produces—incorrect though they may be—feel right!

These sensory illusions occur because flight is an unnatural environment—our senses are not capable of providing reliable signals that we can interpret and relate to our position in three dimensions—without visual reference.

Does "seat of the pants" flying work in IFR weather? Judge for yourself: Anyone sitting in an airplane that is making a coordinated turn, no matter how steep, will have little or no sensation of being tilted in the air—unless the horizon is visible. Similarly, it is possible to gradually climb or descend without a noticeable change in pressure against the seat. In some airplanes, it is possible to execute a loop without pulling negative "G's," so that without visual reference, you could be upside down without being aware of it. That's because a gradual change in any direction of movement may not be strong enough to activate the fluid in the semicircular canals, so you may not realize that the aircraft is accelerating, decelerating, or banking.

Instrument flying

The obvious method to prevent disorientation is the instrument rating. But, that rating alone is no automatic guarantee, because there is no such thing as "knowing how to fly on instruments." You must continue to practice your skills. You are either formally trained and current—or you are unqualified.

So, don't try to fly through a cloud bank or "scud-run" in low visibility conditions if you aren't a current, instrument-rated pilot. For the unqualified pilot, the sudden loss of visual reference is similar to a sudden loss of eyesight. Emotional pressures surge and you can lose your orientation in less than 20 seconds...you can be starting the infamous aerobatics maneuver known as the "graveyard spiral"...and not even know it.

All pilots should check the weather conditions and use good judgment in flight planning. The VFR pilot should avoid low visibility conditions, such as night flying, fog, clouds, and haze.

And, if you're instrument-rated and current, you should always trust your instruments. Those gyros are much more reliable than the ones inside your head!

Summary

• No pilot can fly in IFR conditions without instruments.
• The inner ear can give false positional information unless there is also a visual reference.
• You can literally fly upside down and not know it!
• You can lose orientation in less than 20 seconds if you are in clouds and are not on instruments!