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Southport, Manitoba, Canada
Steve Pomroy is a professional flight instructor and aviation writer. He has been teaching since 1995 and holds an Airline Transport Pilot License, Class 1 Instructor and Aerobatic Instructor Ratings, military QFI, and an undergraduate degree in Mechanical Engineering. He's written and published three flight training books through his company, SkyWriters Publishing, and has several other books under development. Steve currently teaches RCAF pilot candidates on their Primary Flight Training course.

Thursday, January 31, 2013

Flying Blind

My last post, about the ASI and static port blockages, was inspired by a practice problem in my under-development Commercial Pilot License: Written Exam Preparation. This post is also inspired by a product under development. This time it's a far-less-developed book about flight training exercises and scenario-based training.

When I was reviewing the current (very early!) draft of this book, the exercise that caught my eye was related to instrument flying. We fly by instruments when we lose visual reference because our bodies can't stay oriented in space and as a result we can't stay upright. This is why continued VFR flight into instrument meteorological conditions is one of the biggest killers in general aviation—loss of control in cloud is often fatal.

To help combat this source of accidents we expend great effort in teaching student pilots to avoid the conditions leading to spatial disorientation. To provide an extra last-ditch-hail-mary backup, we also provide PPL students with 5 hours of basic instrument flying training. To support this training, we often refer to the article "178 Seconds". This article was written in response to a study, conducted at the University of Illinios, on pilot survivability after loss of visual reference. The results were compelling. They're summed up nicely in the second paragraph of this article from Transport Canada:
How long can a licensed VFR pilot who has little or no instrument training expect to live after he flies into bad weather and loses visual contact? In 1991 researchers at the University of Illinois did some tests and came up with some very interesting data. Twenty VFR pilot "guinea pigs" flew into simulated instrument weather, and all went into graveyard spirals or roller coasters. The outcome differed in only one respect - the time required until control was lost. The interval ranged from 480 seconds to 20 seconds. The average time was 178 seconds -- two seconds short of three minutes.
Other articles on 178 Seconds can be found here and here.

So, what about the exercise I mentioned?

When students are first introduced to instrument flying, it helps to motivate the training if they understand the concept of spatial disorientation. Spatial disorientation is pretty straightforward on the ground. We have three sources of information: (kinesthetic, vision, and vestibular). As soon as we get airborne, the kinesthetic sense no longer provides useful information since angular and linear accelerations of the aircraft can have the same effect on our bodies as gravity (this is the Equivalence Principle of physics). This leaves us with visual and vestibular senses. That's fine. But if we lose visual reference, we are left with just the vestibular sense. The vestibular sense is easily confused when it isn't cross-referenced to at least one of the other two orientation senses.

So in a cloud, for example, we lose visual reference and subsequently lose our sense of up-vs-down. This is what ultimately leads to fatal accidents such as those that killed JFK Jr., Rocky Marciano, Jim Reeves, and Patsy Cline.

The problem with all of this is that most people have never experienced spatial disorientation. If you haven't experienced it, it's very difficult to imagine or visualize. Some flight instructors compare it to the sense of vertigo you get after spinning around. But it's really not the same thing. It would be useful if we could find a way for students to experience spatial disorientation in a safe and controlled environment. This is where the exercise I was reading about comes in.

Before commencing initial instrument training (ok, it doesn't have to be before, but that seems like the most logical time), we can simulate a loss of visual reference by having our student fly with their eyes closed. That may seem like a pretty nutty idea, but eliminating visual reference—which would be difficult in VFR conditions with eyes open—is necessary for our students to become reliant on the vestibular system alone, and to see where that leads.

So where does it lead? Well, that depends. This little simulation tends to not be as effective as actually entering cloud. Secondary cues such as the sun heating one side of your face, or shining through your eyelids help to maintain orientation and therefore reduce the effectiveness of this demonstration. So it's best if we can do this on an overcast day. There are also at least three ways to approach the exercise. The student can (attempt to) report flight maneuvers flown by the instructor. The student can (attempt to) fly straight and level. Or the student can (attempt to) fly maneuvers (a simple 180° turn works well).

All three of these work to demonstrate disorientation, but the third tends to be the fastest. Personally, I like to use all three, but some might argue that that's overkill. In either case, once the student is disoriented—which you will know because they are either reporting the wrong maneuver or conducting the wrong maneuver—have them open their eyes to get re-oriented.

Students are often entertained by this exercise (which is great for motivation), but more importantly, they develop a deeper understanding and more solid belief in disorientation and the effects it can have on them. This provides them with a pretty solid basis for moving into instrument flying. And it motivates them to avoid flying in weather that is beyond their capabilities once they are license and operating without supervision. In other words, this exercise could be a life saver.

Happy Flying!


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