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What is the perfect scan? There is none, or at least there is no one scan that is
best for all pilots. The most important thing is for each pilot to develop a scan that
is both comfortable and workable.
The best way to start is by getting rid of bad habits. Naturally, not looking out at
all is the poorest scan technique, but glancing out at intervals of five minutes or
so is also poor when you remember that it only takes seconds for a disaster to
happen. Check yourself the next time you are climbing out, making an approach, or
just bouncing along over a long cross-country route. See how long you go without
looking out the window.
Glancing out and giving it the once-around without stopping to focus on anything
is practically useless. So is staring out into one spot for long periods of time
(even though it may be great for meditation).
So much for the bad habits. Learn how to scan properly; first, by knowing where to
concentrate your search. It would be preferable, naturally, to look everywhere
constantly but, as this technique is not practical, concentrate on the areas most
critical to you at any given time. In the traffic pattern especially, clear before
every turn, and always watch for traffic making an improper entry into the pattern.
On descent and climbout, make gentle S-turns to see if anyone is in your way.
(In addition, make clearing turns before attempting maneuvers, such as pylons and
S-turns about a road.)
During the very critical final approach stage, don't forget to look behind and below,
at least once; and avoid tunnel vision. Pilots often rivet their eyes to this point
of touchdown. You may never arrive at it if another pilot is aiming for the same numbers
at the same time!
In normal flight, you can generally avoid the threat of an in-flight collision
by scanning and area 60 degrees to the left and to the right of your center visual
area. This advice does not mean you should forget the rest of the area you can see
from side windows every few scans. Horizontally, the statisticians say, you will be
safe if you scan 10 degrees up and down from your flight vector (figure 1). This
technique will allow you to spot any aircraft that is at an altitude that might
prove hazardous to your own flight path, whether it is level with you, below and
climbing, or above and descending.
The slower your plane, the greater your vulnerability, hence the greater scan area
required.
But don't forget that your eyes are subject to optical illusions and can play some
nasty tricks on you. At one mile, for example, an aircraft flying below your altitude
will appear to be above you. As it nears, it will seem to descend and go through
your level, yet, all the while it will be straight and level below you. one in-flight
collision occurred when the pilot of the higher flying airplane experienced this
illusion and dove his plane right into the path of the aircraft flying below.
Though you may not have much time to avoid another aircraft in your vicinity,
use your head when making defensive moves. Even if you must maneuver to avoid a
real in-flight collision, consider all the facts. If you miss the other aircraft
but stall at a low altitude, the results may be just as bad for you as a collision.
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