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The placement of the
base leg is one of the more important judgments made
by the pilot in any landing approach. The pilot must
accurately judge the altitude and distance from which
a gradual, stabilized descent results in landing at
the desired spot. The distance depends on the altitude
of the base leg, the effect of wind, and the amount
of wing flaps used. When there is a strong wind on final
approach or the flaps are used to produce a steep angle
of descent, the base leg must be positioned closer to
the approach end of the runway than would be required
with a light wind or no flaps.
Landing flaps may be partially lowered, if desired,
at this time. Full flaps are not recommended until the
final approach is established. A drift correction is
established and maintained to follow a ground track
perpendicular to the extension of the centerline of
the runway on which the landing is to be made. Since
the final approach and landing are normally made into
the wind, there is somewhat of a crosswind during the
base leg. This requires that the airplane be angled
sufficiently into the wind to prevent drifting farther
away from the intended landing spot.
The base leg is continued to the point where a medium
to shallow-banked turn aligns the airplane’s path
directly with the centerline of the landing runway.
This descending turn is completed at a safe altitude
and dependent upon the height of the terrain and any
obstructions along the ground track.
The turn to the final approach is sufficiently above
the airport elevation to permit a final approach long
enough to accurately estimate the resultant point of
touchdown while maintaining the proper approach airspeed.
This requires careful planning as to the starting point
and the radius of the turn.
Normally, it is recommended that the angle of bank not
exceed a medium bank because the steeper the angle of
bank, the higher the airspeed at which the airplane
stalls.
Since the base-to-final turn is made at a relatively
low altitude, it is important that a stall not occur
at this point. If an extremely steep bank is needed
to prevent overshooting the proper final approach path,
it is advisable to discontinue the approach, go around,
and plan to start the turn earlier on the next approach
rather than risk a hazardous situation.
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