You See Much Less Than You Think You Do 

November 17, 2025  

Have you ever wondered why being able to see other airplanes in the air can be so difficult? Even when you’re getting ATC traffic advisories or looking at targets on an ADS-B screen, actually seeing those airplanes doesn’t really seem a whole lot easier. So, imagine how much more challenging it would be for a pilot whose entire visual field had been narrowed down to the diameter of a drinking straw. That poor soul would be relegated to an endless—and likely fruitless—scan of the entire sky, one tiny circle after another. Can you even imagine?

Well, as it turns out, we don’t have to try to imagine doing this, because every time any of us has ever looked for other airplanes, this is exactly what we have been doing. Despite having a 180-degree perspective of the world, it’s just a tiny area that’s actually capable of seeing other airplanes until they’re practically right on top of us.

If you’re a pilot, it’s likely that your vision is pretty good. Most of us have 20/20 vision, which means that we can see, from 20 feet, what the average person is able to see at 20 feet. But, that visual acuity is only true of a minuscule area at the very center of your visual field. How small is it? Well, if you were to hold a drinking straw up to your eye as though it were a telescope, what you’d be able to see through that straw would give you a pretty good idea of just how small that area really is. Despite having 180 degrees of vision, most of it ranges between only being somewhat useful and almost useless—especially when it comes to seeing things like airplanes. It’s only when those airplanes happen to be within the drinking straw that we’re able to see them. The foveola—part of the eye we’re talking about—is only about 1.0-degree wide.

If you don’t happen to have a drinking straw handy, try this. Make a thumbs up sign and extend your arm as far in front of you as you can. In this position, the height and width of your thumbnail will give you a pretty good idea of just how narrow your foveola really is. And the whole problem with finding other airplanes is that it takes a very long time to scan the entire world around you, when you’re forced to do that one thumbnail at a time.

But doesn’t it seem like you’d be able to see at least reasonably well in a much larger portion of your visual field? Well, it does seem that way, but let’s look at why you really can’t. There’s a somewhat larger area that surrounds the foveola called the fovea, and it’s a lot wider than the foveola. We can simulate that area by replacing the drinking straw with something a little wider—a paper towel roll. And this would allow you the ability to scan the air around you more efficiently. Finding an airplane through a paper towel roll does seem like it would happen much faster than finding one through a drinking straw. But this comes with a price, because the average visual acuity within the paper towel roll drops to about 20/40. With that reduction in visual acuity, you’d need to be at 20 feet to see what most would see at 40 feet. To put this into perspective, pilots whose vision is 20/40 aren’t allowed to fly for hire. Why? Because they’re less likely to be able to see and avoid the airplanes around them.

What about that technique we’ve all heard of in which you divide the sky down into manageable 10 to 15-degree wedges and scan each of those for a few seconds before moving on to the next. It’s definitely better than the alternative of trying to rapidly scan the whole sky at once. But, in reality, this method only converts something that’s nearly impossible and makes it ever so slightly easier. It is, after all, still a very time-consuming task to scan a 15-degree wedge of the world one thumbnail at a time—especially when we consider that this scanning doesn’t occur only along a line, but rather in an entire area that has both horizontal and vertical axes.

The truth is that having a 180-degree visual field creates the illusion that any airplane around you would almost instantly become visible with a casual glance. But they don’t, and now you have a better idea of why.

So, what is a pilot to do in our see-and-avoid flight environment to most effectively prevent mid-air collisions? Our instinct may be to focus on ways to improve our vision, but I think a broader approach is actually what we should be looking for. A large part of aviation safety centers on being acutely aware of exactly what we’re asking any piece of equipment to do, and knowing whether or not that equipment is capable of actually doing that thing. You’d probably never even consider intentionally spinning an airplane that was specifically placarded against spins. That airplane has certain limitations, so we respect those limitations, and we don’t spin it. Along the same lines, our eyes have significant limitations in what they’re able to tell us. Expecting them to detect all the other airplanes operating around us is disregarding those limitations. It’s relying on something that our eyes are not particularly good at doing. In the grand scheme of things, detecting the subtle differences between unimaginably small but rapidly approaching aircraft and the empty sky that surrounds them is much more difficult than it seems. While it’s important to continue looking very carefully for other airplanes, it’s critical that we also focus attention on supplementing our vision with other collision avoidance strategies to minimize the limitations of our eyes. Become more predictable. Use ADS-B. Fly published and standard procedures. Be where other pilots are thinking you’re going to be, doing what they think you’re going to be doing.

If our eyes were required to be equipped with a warning placard, that placard would likely read, You see much less than you think you do.