Each of the above scenarios has a common flight phenomenon - SPATIAL DISORIENTATION.
Disorient means to mix up; confuse; to cause to lose one’s sense of direction, perspective or time. Spatial disorientation is the loss of position sense in relation to the earth’s surface. In the aviation environment, the ultimate consequence is loss of control with the terminal maneuver being a spiral dive - often vertical or inverted! To the accident investigator, the telltale signs of a disorientation accident site are obvious - one of high speed impact with or without control or in-flight structural failure. (Illustration 1).
1. Twin Otter - Controlled Flight into Terrain (C.F.I.T)
The fatality rate for a disorientation mishap is 90% or greater. As a physician this is similar odds to giving a patient a positive HIV laboratory result or biopsy for carcinoma of the pancreas or ovary. The difference being the time to the terminal event and that with understanding and insight, the disorientation accident is preventable. No pilot, student, private, commercial, instrument, float, aerobatic, military or air transport rated is immune to this deadly phenomenon! It is difficult for the landlubber or uninitiated aviator to comprehend the danger of pressing on from visual to instrument conditions.
The Transport Canada Safety Bulletin - Take Five .... for Safety, entitled “178 Seconds” describes the typical scenario of scud running. It refers to the University of Illinois research project set up to determine how long non-instrument rated pilots take to lose control of their aircraft in simulated instrument conditions. The range was 20 to 480 seconds with an average of 178 seconds! Once in instrument conditions their average lifespan was just under three minutes - of the 20 students all eventually lost control.
Several years ago on an instructor re-ride, Roy Israel gave me an in-flight demonstration that is nauseatingly vivid to this day. He mimicked the flight control inputs and gyrations of a recent commercial pilot candidate flying straight and level under the hood. The initial transgression was a gentle right spiral dive, then a brief correction to straight and level. Next the nose came up and we rolled left and into a spiral dive that was near vertical with alarming speed. It was all we could do to throttle back and recover before the engine redlined. My mouth was dry and heart raced as my mind drifted back to 1978 and Bowen Island...
The weather for this flight from Pitt Meadows to Comox Airbase was VFR as forecast with residual cumulus over Howe Sound and the North Shore mountains. The trip was uneventful as we droned westward toward Bowen Island. A cloud bank over the mainland did not appear to be a problem.
POOF! Instant gray, uniform and everywhere. No horizon, mouth dry, fast pulse. Wife, stone silent. Oldest daughter in the rear seat, a seasoned aviator .... “Daddy, it’s foggy outside.” A quick look left then right, still no horizon. A swivel over both shoulders and still no outside reference. The engine droned on but my brain says we’re suspended in time and space. A voice inside my head shrills “Jack, you are in deep shit!”. Check the flight instruments. Impossible! We entered this mess straight and level and my mind and body feel the same, but .... the airspeed indicator is unwinding through 50 knots and the attitude indicator shows the little aircraft profile in a nose up and right bank attitude. Unusual attitude with a stall seconds away! Recover, nose down and level the wings. Turn to reciprocal heading and wait and wait and...Time stands still, loses all meaning. Then POOF! English Bay, anchored freighters and a natural horizon! The rest of the flight was uneventful.
This brief insightful encounter with disorientation made me an instant believer of its deadly peril. I was astounded by the rapid transition from controlled flight to an unusual attitude in mere seconds. Contributing factors included surprise, distraction and the surreal world of instrument conditions. Under these conditions, 24 hours of hood time was almost not enough to survive. There is no doubt that in cloud experience is invaluable. The importance of recognizing and recovering from unusual attitudes was driven home as was the pre take-off setting of the heading indicator for the reciprocal turn. In retrospect, I did commit two errors: The turn, rather than rate one (3° per second), was a steep aerobatic fighter pilot variety and to the right towards the concealed peak of Bowen Island. I will never know how close we came to terrain and I don’t care to. There was a touch of panic and the adrenalin was flowing hot. But we survived to fly another day!
It is difficult to describe the emotional and physical reactions in this situation. During my lifetime, I have encountered several life-threatening crises. These include personal health (subarachnoid hemorrhage), fishing, logging and aviation adventures. In aviation, a close encounter with another aircraft always results in a strange metallic taste in my mouth - The taste of raw adrenalin. However, the absolute dysphoria and terror of spatial disorientation is by far the worst and for many pilots the last they will experience. One of my sage flying instructors, John Brongers, put this into perspective after I recounted to him my Bowen Island fiasco:
“Jack” he asked, “If I was sitting in the right hand seat, instrument rated, and told you I could fly you out of this mess, would you sign this blank cheque?” I responded “Yes, immediately!” The amount was immaterial and the recipient could have been the devil himself. I call this “Lotto Equivalent” dysphoria. It is hard to convey to the non-aviator the intensity of the mental anguish.