Best Foot Forward
I really appreciate the article by Chet Ludlow “Setting Limits in IMC” published in the December issue of IFR. With initial recurrency instrument students, I have taught this way for many years and found it most effective. However, even when I apply the maximums of Chet there is still a missing ingredient.
That ingredient is inadvertent adverse yaw. Almost universally the pilots who wander back and forth, even minutely on an ILS final, are doing it without rudder. Consequently, at the initial input of bank, however small, the heading indicator goes the wrong direction. Thus the pilot holds the bank too long before returning to level wings and goes through the course.
The leveling of the wings ends up also with adverse yaw, which leaves the aircraft pointing away from the course. The reaction is to immediately turn back to the course—and thus repeat the errant process of a continuum of pilot-induced oscillations across the course. This is often aggravated by knee-jerk responses to attempt to stop the wandering from course. The term “chasing a needle” often applies well.
