Tuesday, April 23, 2013
The Eyes Have It
The difference between “looking” and “seeing”
|Where you should look when landing changes from short final to the flare as your focal point moves from the numbers toward the end of the runway. One school of thought says to stare straight ahead; another says to use your peripheral vision for height information.|
Lay the magazine down where you can still read it. Then, raise the index fingers on both hands and hold them both out in front of you pointing vertically up. Make believe it's some sort of weird dance move. Hold them at arm's length and about a foot apart. Now, turn your head and focus on your left index finger. Got it? Okay, now, without moving your head or your eyes, continue staring at your left finger and notice how sharp your right finger is in your peripheral vision. Pretty fuzzy isn't it?
Now, still staring at your left finger move your right hand/finger towards it and see how close your right finger has to be to your left finger before they're both sharp. Generally, they have to be within a few inches for both of them to be sharp. So, what did we just prove? We just proved that as soon as something is even slightly outside of our point of focus, the visual information being generated by it gets very vague, very quickly.
We're talking about this because one school of thought says that you should be staring straight ahead when landing, and relying on your peripheral vision to keep you straight and give you height information during flare. This is especially prevalent in taildraggers, where often you can't actually see over the nose, but you hear it mentioned in nosedraggers from time to time, too. In fact, for decades, yours truly taught landings that way. However, at some point in the last 10 years, it became obvious that everything out in the fringes of vision is fuzzy and a different approach was needed.
According to the FAA, as soon as we get five degrees outside of the point of focus, 20/20 vision degrades to 20/100. That's right: While some of us are landing, the visual information that we're depending on is being generated by 20/100 vision or less. If we were walking, that would qualify us for a white cane. But, we're hurtling at the ground at 80 mph where 20/100 vision just doesn't cut it. So, what do we do about it?
Since we only have about a narrow cone of 20/20 vision, it's practical that we conduct ourselves as if we were looking at the world through a soda straw. We need to recognize that the information coming from that narrow cone of focus is the best we're going to get. That doesn't mean, however, that we totally ignore our peripheral vision. As far as that goes, we couldn't ignore our peripheral vision even if we wanted to, because our mind will subconsciously see what's out there in the fringes whether we want it to or not.
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