Normally, the first ground reference maneuver the pilot
is introduced to is the rectangular course.
The rectangular course is a training maneuver in which
the ground track of the airplane is equidistant from all
sides of a selected rectangular area on the ground. The
maneuver simulates the conditions encountered in an
airport traffic pattern. While performing the maneuver, the altitude and airspeed should be held constant.
The maneuver assists the student pilot in perfecting:
Practical application of the turn.
The division of attention between the flightpath,
ground objects, and the handling of the airplane.
The timing of the start of a turn so that the turn
will be fully established at a definite point over
the ground.-
The timing of the recovery from a turn so that a
definite ground track will be maintained.
The establishing of a ground track and the determination of the appropriate "crab" angle.
Like those of other ground track maneuvers, one of the
objectives is to develop division of attention between
the flightpath and ground references, while controlling
the airplane and watching for other aircraft in the
vicinity. Another objective is to develop recognition of
drift toward or away from a line parallel to the intended
ground track. This will be helpful in recognizing drift
toward or from an airport runway during the various
legs of the airport traffic pattern.
For this maneuver, a square or rectangular field, or an
area bounded on four sides by section lines or roads
(the sides of which are approximately a mile in length),
should be selected well away from other air traffic. The
airplane should be flown parallel to and at a uniform
distance about one-fourth to one-half mile away from
the field boundaries, not above the boundaries. For
best results, the flightpath should be positioned outside
the field boundaries just far enough that they may be
easily observed from either pilot seat by looking out
the side of the airplane. If an attempt is made to fly
directly above the edges of the field, the pilot will have
no usable reference points to start and complete the
turns. The closer the track of the airplane is to the field
boundaries, the steeper the bank necessary at the turning points. Also, the pilot should be able to see the
edges of the selected field while seated in a normal
position and looking out the side of the airplane during
either a left-hand or right-hand course. The distance of
the ground track from the edges of the field should be
the same regardless of whether the course is flown to
the left or right. All turns should be started when the
airplane is abeam the corner of the field boundaries,
and the bank normally should not exceed 45°. These
should be the determining factors in establishing the
distance from the boundaries for performing the
maneuver.
Although the rectangular course may be entered from
any direction, this discussion assumes entry on a
downwind.
On the downwind leg, the wind is a tailwind and results
in an increased groundspeed. Consequently, the turn
onto the next leg is entered with a fairly fast rate of
roll-in with relatively steep bank. As the turn progresses, the bank angle is reduced gradually because
the tailwind component is diminishing, resulting in a
decreasing groundspeed.
During and after the turn onto this leg (the equivalent
of the base leg in a traffic pattern), the wind will tend
to drift the airplane away from the field boundary. To
compensate for the drift, the amount of turn will be
more than 90°.
The rollout from this turn must be such that as the
wings become level, the airplane is turned slightly
toward the field and into the wind to correct for drift.
The airplane should again be the same distance from
the field boundary and at the same altitude, as on other
legs. The base leg should be continued until the upwind
leg boundary is being approached. Once more the pilot
should anticipate drift and turning radius. Since drift
correction was held on the base leg, it is necessary to
turn less than 90° to align the airplane parallel to the
upwind leg boundary. This turn should be started with
a medium bank angle with a gradual reduction to a
shallow bank as the turn progresses. The rollout should
be timed to assure paralleling the boundary of the field
as the wings become level.
While the airplane is on the upwind leg, the next field
boundary should be observed as it is being approached,
to plan the turn onto the crosswind leg. Since the wind
is a headwind on this leg, it is reducing the airplane's
groundspeed and during the turn onto the crosswind
leg will try to drift the airplane toward the field. For
this reason, the roll-in to the turn must be slow and the
bank relatively shallow to counteract this effect. As the
turn progresses, the headwind component decreases,
allowing the groundspeed to increase. Consequently,
the bank angle and rate of turn are increased gradually
to assure that upon completion of the turn the crosswind ground track will continue the same distance
from the edge of the field. Completion of the turn with
the wings level should be accomplished at a point
aligned with the upwind corner of the field.
Simultaneously, as the wings are rolled level, the
proper drift correction is established with the airplane
turned into the wind. This requires that the turn be less
than a 90° change in heading. If the turn has been made
properly, the field boundary will again appear to be
one-fourth to one-half mile away. While on the crosswind leg, the wind correction angle should be adjusted
as necessary to maintain a uniform distance from the
field boundary.
As the next field boundary is being approached, the
pilot should plan the turn onto the downwind leg. Since
a wind correction angle is being held into the wind and
away from the field while on the crosswind leg, this
next turn will require a turn of more than 90°. Since
the crosswind will become a tailwind, causing the
groundspeed to increase during this turn, the bank initially should be medium and progressively increased
as the turn proceeds. To complete the turn, the rollout
must be timed so that the wings become level at a point
aligned with the crosswind corner of the field just as
the longitudinal axis of the airplane again becomes
parallel to the field boundary. The distance from the
field boundary should be the same as from the other
sides of the field.
Usually, drift should not be encountered on the upwind
or the downwind leg, but it may be difficult to find a
situation where the wind is blowing exactly parallel to
the field boundaries. This would make it necessary to
use a slight wind correction angle on all the legs. It is
important to anticipate the turns to correct for groundspeed,
drift, and turning radius. When the wind is
behind the airplane, the turn must be faster and steeper;
when it is ahead of the airplane, the turn must be
slower and shallower. These same techniques apply
while flying in airport traffic patterns.
Common errors in the performance of rectangular
courses are:
- Failure to adequately clear the area.
- Failure to establish proper altitude prior to
entry. (Typically entering the maneuver while
descending.) - Failure to establish appropriate wind correction
angle resulting in drift. - Gaining or losing altitude.
- Poor coordination. (Typically skidding in turns
from a downwind heading and slipping in turns
from an upwind heading.) - Abrupt control usage.
- Inability to adequately divide attention between
airplane control and maintaining ground track. - Improper timing in beginning and recovering
from turns. - Inadequate visual lookout for other aircraft.
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