Scanning & Illusions
Learning to operate an aircraft safely in the flight environment is essential. If we want to become a proficient, professional pilot and show this to our passengers in such a way that they feel safe flying with us. Then there are some things we need to become very good at.
First, we will discuss the one thing that is very important when flying: collision avoidance. I have had my share of near misses in the past, ranging from light twins to F-16 fighters, so looking out of the windows is one of my main priorities.
Remember that when two aircraft approach each other head on at 100 kts (not an uncommon speed) they travel over 3 miles per minute.
And with a visibility of 1.5 miles you will have less than 30 seconds to react before you see the other aircraft.... IF you were looking in the right direction.
As a pilot you need to be constantly aware of your aircraft and the environment where you fly in. Things as visual scanning, blind spots and basic turbulence avoidance as basic pilot skills, are emphasized here.
VFR means Visual Flight Rules. Visual means with the eyes. We therefore need a good lookout to remain clear of clouds and other objects in the air and make sure we do not fall into the trap of a visual illusion.
Scanning while flying
The most effective way to scan during daylight is through a series of short, spaced eye movements in 10 degree sectors starting from left to right. On the way back to your left to take a glance at the instrument panel to check what is happening before starting all over with this visual scan. During the outside scan it is wise to focus on distance objects on the ground before 'staring' into the blue sky. Else the phenomenon described below can arise very quickly.
Looking without seeing, empty field myopia
When looking into a featureless sky, be it grey haze or clear blue sky, the human eyes tend to focus on a point about 10 to 30 feet (3 to 10 meters) away, without you ever knowing/seeing it. Thus you are looking without really seeing anything. Probably missing a lot. No need to say that this can be very dangerous. To avoid this, when scanning in 10 degree steps from left to right also look at several points on the ground at different distances from the aircraft. This keeps the eyes focused on distance. Also avoid 'staring'.
Flying into the sun, especially during sunset and when there is a light haze, good scanning is very important. Aircraft or other objects are much more difficult to see when the sun is behind them (and in front of you) in such circumstances. Even when landing into such conditions. Wearing sunglasses that filter out the blue color of the spectrum (Serengeti drivers for example) can help a great deal and add to safety.
What you can't see sometimes really is there, aircraft blind spots
Aircraft blind spots are by design. There you have it, no more no less. High winged aircraft are great for sightseeing because the wing is on top of the aircraft. More fun when you have people aboard and they want to fly over their house and take pictures. Low wing aircraft have a great view of the sky but looking down can be a problem, but are great when turning to final as the runway remains in sight in contrary to a high wing aircraft.
Basically you have to keep the shortcomings of each design in mind. Not that there's anything wrong with it, but the wing (and the fuselage) gets in the way of the pilot who needs to see other traffic especially when flying near airports or other points of interest. Just be very aware of it and you'll do just fine.
When climbing with a high wing aircraft make shallow turns to watch for traffic overhead, the opposite goes for low wing aircraft in descents, just make shallow turns so that lower flying traffic can be spotted sooner.
On an VFR approach to an airport the situation could arise where a high wing aircraft is flying lower than a low wing aircraft. Especially when the low wing aircraft is descending to a reporting point and the high wing is flying level toward the same point. Both can not see each other and a collision could happen.
What you see sometimes looks quite different
Runways that are wider or narrower than we normally land on or even with an up or down slope can be very deceiving. We have made a table for you to sum up all these illusions. Just think about it and it will make sense.
|Tendency to fly higher than normal approach:||Tendency to fly lower than normal approach:|
|Wide runway||Narrow runway|
|Down sloping runway||Up sloping runway|
|Bright approach and runway lights||At night (black hole)|
|Steep surrounding terrain||Above featureless terrain|
|Rain on windscreen and haze|
During preflight, take note on how the destination airport is situated. With the above table in mind most surprises can be avoided (like trying to flare too high because the runway is twice as wide than the home airport, I have seen this happen with a student and the touchdown was a bit harder than we were used too).