Ice bridging is the idea that if you operate the boots too early, you will stretch the ice but not fracture it. When the boot deflates following the cycle, the stretched ice will remain, with more ice building on top of it. Yet there is not a single test conducted in anyone’s icing research wind tunnel that has been able to replicate ice bridging, nor are there any accidents that document ice bridging as a cause or contributory factor.
In a study of icing accidents that I presented as a paper for the American Institute of Astronautics and Aeronautics in 2006, I identified 142 events in which the pilot made the decision to land due to ice accumulation; in 84 of these, the decision was made before any aerodynamic consequences had been encountered. In only 23 of these 142 cases was a successful precautionary landing made.
The original intent of contemporary cockpit automation arose from the capabilities view of technology, in particular the capability to optimize aerodynamic efficiency while also optimizing airspace utilization. This was, and still is, clearly a machine in the service of man. The intent of automation began to migrate toward the cybernetics view with the notion that we could automate human error out of the equation.
I spent the day after he died doing the things one does, particularly trying to figure out what to do with his ashes. One friend, a pilot at my airline, asked what the funeral plans were. I told her that we would probably inter Dad out there at the Jordan Cemetery in Indiana. Knowing something of his aeronautical passions, she texted back, “Oh, that’d be nice. He’d get one last airplane ride.”
“The pilot in command of the aircraft shall be directly responsible for its operation and shall have final authority as to operation of the aircraft.” Encoded here is that singular autonomy, that point of application of free will, that has not changed through eons despite all of the changes in the architecture of man-machine interface as well as the changes in management theory and even the emphasis on crew resource management.
On a hot, mosquito-laden summer night in July of 1969, we had taken the liberty of renting a black-and-white television, which we perched on a small table in the larger front room of the trailer. We dined on our usual Swanson TV dinners warmed up in the toaster oven, and spent some time fiddling with the rabbit ears to get a good signal before we settled down to listen to Walter Cronkite, Wally Schirra and the crowd down at the Cape. It was going to be quite a night.
On two recent occasions, I have spent my day staring down FAR 121.613. Both cases required a more in-depth study of the day’s weather than a simple scan of the TAF. Regardless of which part of the FARs you are operating under, the area forecast discussions put out by local forecasters are incredibly valuable when preparing for a day’s flying. They will give you the feel of a personal briefing.
Following uncontrolled collisions with the ground, hard landings are the second most prevalent outcome attributable to structural icing. Unlike the uncontrolled collision data, hard landing events are generally well documented; almost no one is fatally injured, and the sequence of events and aircraft response is pretty easy to map out. This set of data may give us a window into an obscure and overlooked aspect of aerodynamic icing… drag rise as a function of angle of attack.
I attempted a turn away from the ridge, probably induced an accelerated stall at some point, and we hit the trees. We spent about 43 hours in the woods on the side of Johnson Mountain. My friend passed away sometime during that period. I had no survival gear whatsoever. I had no flight plan. No one knew where I was. I did have an ELT, and it saved my life.