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Feature Article: Wind and Groundspeed
Turning as low levels from a crosswind path to a downwind path
can be hazardous. It leads to the terrible downwind turn stall
accident. When the aircraft turns from a crosswind to a downwind
direction at low altitudes, all at once the ground seems to go
by much faster. In actuality, it is, but the reaction to the sensation-illusion
is that the airspeed has changed as well. It has not and should
not. The wind speed added to your airspeed has caused an increase
in your ground speed. Close to the ground fly the airspeed not
the ground speed. To allow for student errors in this regard all
ground reference should be flown a cruise power in trainers. The
downwind turn illusion will be exacerbated if the pilot has developed
a (bad) habit of trying to look around the cockpit window post
during the turn. (See material on peripheral vision.)
As a private pilot you are expected to perform a turn about
a point. This means a circle at a constant altitude, of a constant
radius with ground speed a variable as affected by the wind. As
a commercial pilot you are expected to do a turn on a point. The
turn on a point has a constant radius but you are expected to
keep the wing tip on the point while flying the circle. This can
only be done if you fly a constant ground speed. You should know
the difference between the two.
Every ground speed has a critical altitude at which a given
radius circle will allow the pilot to keep the wingtip on a point.
As the circle is flown the wind affects the ground speed differently
at every point. To keep the tip on the point the pilot must vary
his altitude. Changing altitude will vary the ground speed. Enter
a slight dive when the point moves ahead of the wingtip (tailwind
component)and a slight climb when the point moves behind the wingtip.
Practicing turns on a point at about 640' in a C-150 will give
you an idea of how the wind affects ground speed. With this knowledge
you will be better prepared to cope with the sensations present
in the downwind turn. The best defense is to fly a wide downwind
if the wind direction is forcing you toward the runway. When you
slow the aircraft on the downwind add some more wind correction.
Last Modified January 5, ©2026 TAGE.COM
