Plane & Pilot
Tuesday, April 23, 2013

The Eyes Have It


The difference between “looking” and “seeing”


Let's use landing flare as an example of where it may be a good idea to remember that only the middle 5% of our vision is giving us accurate information. So during flare, we're going to force ourselves to direct that narrow visual cone to look at and analyze specific areas.

When we're pulling the airplane level in ground effect, one visual method often used is to fixate on the far end of the runway for as long as we can see it. This works, but the information isn't as finite as it would be if we picked far, distant points on both sides of the runway and continually shifted our focus from one to the other. This triangulation gives us more exact visual information and forces our peripheral vision further to the side, so even more information is gathered.


It's important to know the difference between "looking" and "seeing." When scanning for traffic against a relatively featureless background, your eyes aren't picking out a specific point and may tend to focus short, a phenomenon called "eye myopia."
As the airplane settles into ground effect and we hold it off, often the nose comes up and covers the middle of the runway. At that exact moment, our focal point moves to the side of the cowling where the edge of the runway hits it. It's the apex of the triangle formed by the leading edge of the wing, the side of the nose and the edge of the runway. In effect, we're using the nose as if it were the rear sight on a rifle, and the edge of the runway is the front sight, and we're trying to keep the intersection of the two in a specific alignment. The way in which the side of the runway moves up and down the side of the cowling tells us exactly what our airplane is doing both while in ground effect and while in final flare.

If for instance, while in flare, the airplane turns even slightly left, the point where the runway edge hits the cowling will move down the side of the cowling, and the visual triangle will get smaller. The point moves up if we turn right, and the fuzzy triangle in our left peripheral vision will get bigger (we "sense" the change more than seeing it).

While we're holding the aircraft off and it's settling into ground effect, the point moves up the side of the nose as the airplane moves. The visual triangle, however, remains pretty much the same size because our nose has moved neither left nor right.

That point is continually talking to us. If we're looking straight ahead and depending on our peripheral vision to tell us what's happening, our 20/100 vision field will include that point, and the information we receive from it will, at best, be an approximation.

The ability to direct our 20/20 visual cone at the exact points where the most accurate visual information is being generated is what defines our visual acuity. And our visual acuity is often what defines us as pilots. The old saying says, "You can't fix what you can't see," and no truer words were ever spoken.



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