By Ted Delanghe | June 1, 2022 Estimated reading time 6 minutes, 54 seconds.
The number one priority of every pilot is to maintain positive control and not hit the ground.
Sage advice, along the same lines as ensuring you have the same number of landings as takeoffs. To accomplish both goals, you need to literally know which way is up at all times. That’s generally no problem on the ground, but in flight it is very easy to have the sensation of being in a particular orientation that differs greatly from your actual situation.
Enter the murky world of “the leans” and other fun stuff. As if just handling an aircraft doesn’t present enough challenges on its own, IFR flight — “flying blind” as it was initially referred to — has its own set of issues, starting with false sensory illusions.
Accident reports have long confirmed that continuing VFR flight when inadvertently encountering IMC conditions is a ready-made formula for becoming disoriented with subsequent loss of control. The formula is very simple for a non-IFR rated pilot: loss of the natural horizon = risking vertigo or spatial disorientation. Both can lead to a really bad day at the office.
One of the most unforgettable experiences I’ve had in being big-time disoriented occurred in a formation flight in CF-5s. I was on the wing, and shortly after takeoff we were in solid, dark cloud. My only reference to the outside world was the lead aircraft’s tip tank about 10 feet away, and my job was to stay put.
For the first hour of flight — still in cloud — everything felt normal, although my internal gyros were becoming a bit foggy. As we started a descending turn about 60 miles out from our destination, there was a momentary break in the clouds that I just happened to glimpse as a backdrop to the lead aircraft. The problem was, I saw green terrain on top and blue sky on bottom — 180 degrees reversed from the normal blue sky on top and green terrain on bottom. Picture that for a second!
Talk about my brain going into overdrive. I would have sworn we were inverted, and everything in my brain’s interpretation of that brief glance of green on top/blue on bottom reinforced that feeling.
I took a quick look at the attitude indicator and, sure enough, it said we were upright. “Can’t be!” screamed the primitive “fight or flight” part of my brain. “Must be!” said the logical part.
Disorientation can occur when there is a conflict between the instrument indications and what the pilot perceives is the actual attitude. In this case, it wasn’t a conflict. It was a war, and a matter of grin and bear it while trying to distance myself from that almost overwhelming perception of being inverted. Even when I realized I had glimpsed a very blue lake below a green, forested shoreline — and wasn’t hanging from my straps upside down — it was not a fun time while the various parts of my brain had an all-out brawl. However, in due course, we descended below cloud, and all returned to normal.
Fun times, indeed! There’s a lot of good information we first learn in basic flying training that bears a second look — one of these being disorientation in IFR flight from either visual or sensory illusions. Many are a direct result of the vestibular system sending incorrect signals to your brain, telling it you are going in one direction when you are actually going in another.
A common example is appropriately called “the leans.” This can happen when a pilot flying IFR is distracted from monitoring the instruments and gradually enters a shallow prolonged turn. Upon noticing the unintended bank angle, the pilot rapidly returns to straight and level flight on instruments, resulting in a very strong feeling of continuing a turn in the direction of recovery. It is a feeling so strong that the pilot leans towards the opposite side of the perceived turn to maintain a sense of balance.
There are quite a few other sensory illusions, vestibular and otherwise: relative motion/vector illusion, visual autokinesis, space myopia, graveyard spin, Coriolis illusion, etc. The problem is that if you don’t have the knowledge and/or experience to cope with such issues, you can get yourself into big trouble very quickly. Inexperienced pilots and those short on proficiency or recency of experience are highly susceptible to spatial disorientation, and find it very difficult to ignore sensory illusions in favor of believing instrument indications.
Being prepared is half the battle in coping with such eventualities. Know what types of spatial disorientation you may experience, along with causal factors such as diversion of attention, task saturation, and sensory overload/deprivation.
There’s a ton of information on the internet on all these subjects, and the research you invest in today may bring a load of benefits the next time you find yourself leaning in one direction, or another.
And last but not least, remember the golden rule of IFR flight: “Never trust your senses. Always trust your instruments.” You’ll be very glad you did.
