All pilots during their training go through thorough theory on how the basics of human senses work. We do this in relation to flying, so that we can understand how the sensory information is being received, and identify when it is and isn't accurate. From a genetics perspective, we humans evolved our senses to maintain orientation on the ground, where the earth is always stationary. What I mean by this is, up is always up and directions are always what they are; left = left, you get the idea. But the 3-dimensional world of flying is unfamiliar to the body, which is where we get these illusions from. After all, unlike our aviary counterparts, the human race has yet to transcend the world of flight. No matter how much a pilot will learn in flight school, the ability to understand the limits of our senses can only be "taught" when they fly in the practical world. Only then do pilots truly learn the limits of their own bodies & when not to trust them.
In this blog, I want to talk about a few of the illusions I have faced myself. While most were taught in flight school, I did not realize the severity of them until I started commercially in the north, where what was once words on paper were dramatically exemplified in real life. I will highlight only a few of the illusions that I find interesting to talk about. You might be asking, why is this even important to talk about? I mean, aviation is pretty safe now and rarely do we have accidents, right? While you are correct, it hasn't always been this way. And other sub-divisions of aviation, like general flying, are still working hard to improve safety. In fact, according to the FAA (Federal Aviation Administration) about 5-10% of all accidents can be attributed to spatial disorientation, 90% of which are fatal (Antunano, FAA).
OPTICAL ILLUSIONS
Of all of our senses, vision in my opinion, is the most important. However, there are several illusions in aviation that can detriment the use of vision. Most of these have to do with landing phases of flight, when pilots regularly swap between instrument use and visual references outside the cockpit.
Narrow Runway vs Wide Runway
A runway that is narrower than usual can create the illusion that the aircraft is higher than it actually is. This is because most times during training, pilots train at the same airport and runway at all times. Therefore in the early stages of the training, they learn what the runway should look like as the aircraft approaches at an angle (angular descent). But when they start flying out to different runways with varying widths, this perception is put to the ultimate test because the eyes want to see what has been taught and ingrained during the training days. This confuses the brain and this is what causes the illusion. The fact that the pilot believes to be higher than normal (when in fact they are on the correct approach angle) causes them to fly lower than the optimum angle, which means they run the risk of landing short. The opposite is true for runways wider than normal, the pilot thinks the aircraft is lower, causing them to fly higher and overshooting the landing point. In the diagram, you can see this in action. The orange dots represent the correct path, with the aircraft under the influence of the illusion. In the north, we see this all the time, especially when we constantly swap between runways in the remote communities, and those of larger airports like Thunder Bay or Winnipeg. One good way to alleviate this is to use the PAPI which are guiding lights for angular orientation based on aircraft distance. However, these are not available at all times at all airports, so sheer experience and proficient use of instruments is the best defence in this regard.
The Black Hole Illusion
This is one of the most famous illusions in the world of flying. It is also heavily studied by organizations around the world, including Boeing. What's required for this to occur? Well for starters, there is basically no light on the ground for reference. The sky is also dark, there is no horizon and little to few other cues for spatial awareness. The pilot therefore is conducting an approach in ultimate darkness, with just the lights of the runway ahead of him/her. In this type of illusion, all sensory sources are involved, but primarily it involves not being able to see enough reference outside, causing the brain to feel like the aircraft is too high in relation to the runway. This causes the pilot to fly the aircraft dangerously low, often hitting terrain far prior to the runway. This is known as Controlled Flight Into Terrain, or CFIT for short. This is a major issue that still exists today, and while CFIT can happen in any number of ways, arguably black hole illusion is the most dangerous kind.
This kind of illusion is seen almost everyday by those of us working in the high north. For example, one certain airport that comes to mind is Round Lake, which serves the community of Weagamow First Nation. Approaches done on Runway 03 occur over a lake meaning no ground lights leading to the runway, and because the community is very small and close to the airport, there are absolutely no other lights in the vicinity for spatial guidance. On the dark winter nights, the horizon disappears too. This becomes particularly difficult in one specific condition. If there is blowing snow on the approach, the difference in track (the line the aircraft follows to the runway) and heading (where the aircraft nose is pointed), combined with the ferocity of wind gusts, can cause pilots to be disoriented very easily. You are basically flying completely, and absolutely blind unless you have good knowledge of both instruments and the surrounding area. One good way to alleviate this is to run instrument approaches when visual guidance is questionable. Even with the approaches, it can be difficult to maintain good cognition. This is why it is critically important to be proficient in flying the aircraft, and trusting the instruments (even more than your own self). At some point, we must accept our limits and use all the other resources around us. And nowhere is that more evident than in black hole illusions.
Protective Measures Against Illusions
There are some clever methods the industry has developed to help alleviate some of these issues. First, is a solid training foundation. It is imperative that during the flight school days of a pilot's career, they spend time reading and understanding the limits of the senses. A training centre is the perfect place to work with an instructor to put the aircraft in undesired states and recover, using nothing but the instruments to help you. Sometimes small hoods are placed on a student's head which blocks their ability to look outside, forcing them to learn to trust and use instrument information. And as shown in the examples above, developing this trust on the instruments can prove to be the best asset against our own senses.
Another good weapon in our arsenal is the instrument rating, which is a follow up to the first point I made. An instrument rating is not necessarily for just those who want to fly in conditions with no visual reference. It is, like I mentioned before, a great tool for general VFR pilots to use incase they find themselves in less than ideal conditions. Skills such as proper scanning, running approaches, and trusting the instruments all help to paint a solid 3-dimensional picture of the aircraft in our mind. This allows us to work with more than just what we see.
At last is sheer experience. I have said it before, and I will say it again. There is absolutely no replacement for experience and the knowledge that comes with it. Take me for example. Fresh out of flight school, I would have never thought to have seen the things I have seen, and put my senses to their ultimate test. In Waterloo and the surrounding places I flew, every airport was a runway with full lights and lots of city lights to surround it. While in training we tried to simulate some of what the illusions are like, it was nothing compared to the north. Only until I came to the north, and flew in some of these very remote locations did I realize the scope of illusions and the risk they impose. In all honesty, it humbled me and gave me a sense of appreciation for how hard our senses work subsconsciouly, but also just how much we lack when it comes to flying. The amazing learning experience I got with the captains I flew with, gave me the ability to understand and "see" these illusions, up close.
CLOSING
So there you have it. Those are the two super important illusions I wanted to talk about in this post. While there are many other types of illusions pilots face, these I have faced most often, so I chose to leave some of the other types of illusions out of this post. If you want to further yourself with research, just google aviation illusions and you will be greeted with some fantastic articles. Next time you are flying around, especially during a time you can't see too well outside the window, just take pause and appreciate the limits of the human body, and how we have come up with genius ways to overcome them safely, one landing at a time.
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