Airplane Flying Handbook (FAA-H-8083-3C)
Chapter 7: Ground Reference Maneuvers
Introduction
During initial training, pilots learn how various flight control pressure inputs affect the airplane. After achieving a sufficient level of
competence, the pilot is ready to apply this skill and maintain the airplane, not only at the correct attitude and power configuration,
but also along an appropriate course relative to objects on the ground. This skill is the basis for traffic patterns, survey, photographic,
sight-seeing, aerial application (crop dusting), and various other flight profiles requiring specific flightpaths referenced to points on
the surface.
Ground reference maneuvers are the principal flight maneuvers that combine the four fundamentals (straight-and-level, turns, climbs,
and descents) into a set of integrated skills that the pilot uses in everyday flight activity. From every takeoff to every landing, a pilot
exercises these skills to control the airplane. Therefore, a pilot needs to develop the proper coordination, timing, and attention in
order to accurately and safely maneuver the airplane with regard to the required attitudes and ground references.
The pilot should be introduced by their instructor to ground reference maneuvers as soon as the pilot shows proficiency in the four
fundamentals. Ground reference maneuvers call for manipulation of the flight controls using necessary control pressures to affect the
airplane’s attitude and position by using the outside natural horizon and ground-based references with brief periods of scanning the
flight instruments.
Maneuvering by Reference to Ground Objects
Ground reference maneuvers train the pilot to accurately place the airplane in relationship to specific references and maintain a
desired ground track. While vision is the most utilized sense, other senses are actively involved at different levels. For example, the
amount of pressure needed to overcome flight control surface forces provides tactile feedback as to the airplane's airspeed and
aerodynamic load.
It is a common error for beginning pilots to fixate on a specific reference, such as a single location on the ground or a spot on the
natural horizon. A pilot fixating on any one reference loses the ability to determine rate, which significantly degrades a pi lot’s
performance. By visually scanning across several references, the pilot learns how to determine the rate of closure to a specific point.
In addition, the pilot should scan between several visual references to determine relative motion and to determine if the airplane is
maintaining, or drifting to or from, the desired ground track. Consider a skilled automobile driver in a simple intersection turn; the
driver does not merely turn the steering wheel some degree and hope that it will work out. The driver picks out several references,
such as an island to their side, a painted lane line, or the opposing curb, and uses those references to make almost imperceptible
adjustments to the amount of deflection on the steering wheel. At the same time, the driver adjusts the pressure on the accelerator
pedal to smoothly join the new lane. In the same manner, multiple references are required to precisely control the airplane i n
reference to the ground.
Not all ground-based references are visually equal. Awareness of typical visual illusions helps a pilot select appropriate references.
For example, larger objects or references may appear closer than they actually are when compared to smaller objects or references.
Prevailing visibility has a significant effect on the pilot’s perception of the distance to a reference. Excellent visibility with clear skies
tends to make an object or reference appear closer than when compared to a hazy day with poor visibility. Rain can alter the visual
image in a manner creating an illusion of being at a higher than actual altitude, and brighter objects or references may appear closer
than dimmer objects. However, if using references of similar size and proportion, pilots find ground reference maneuvers easier to
execute.
Ground-based references can be numerous. Examples include breakwaters, canals, fence lines, field boundaries, highways, railroad
tracks, roads, pipe lines, power lines, water tanks, and many other objects; however, choices can be limited by geography, population
density, infrastructure, or structures. The pilot should consider the type of maneuver being performed, altitude at which the maneuver
will be performed, emergency landing requirements, density of structures, wind direction, visibility, and the type of airspace when
selecting a ground-based reference.
Ground reference maneuvers develop a pilot's division of attention skill. A pilot needs to control the airplane's attitude while tracking
a specific path over the ground. In addition, the pilot should be able to scan for hazards such as other aircraft, prepare for an
emergency landing should the need arise, and scan the flight and engine instruments at regular intervals to ensure that a pending
situation, such as decreasing oil pressure, does not turn into an unexpected incident.
Ground reference maneuvers place the airplane in a low altitude environment with associated hazards. Pilots should look for other
aircraft, including helicopters, and look for obstructions such as radio towers and wires. In addition, pilots should consider engine
failure and have one or more locations available for an emergency landing. Pilots should always clear the area with two 90° clearing
turns looking to the left and the right, as well as above and below the airplane. The maneuver area should not cause disturbances and
be well away from any open air assembly of persons, congested areas of a city, town, or settlement, or herd of livestock. Before
performing any maneuver, the pilot should complete the required checklist items, make any radio announcements (such as on a
practice area frequency), and safety clearing turns. As a general note, a ground reference maneuver should not exceed a bank angle of
45° or an airspeed greater than the maneuvering speed. As part of preflight planning, the pilot should determine the predicte d
(POH/AFM) stall speed at 50° or at the highest bank angle expected during the maneuver to assure there will be a safety margi n
above the stall speed during the maneuver.
Drift and Ground Track Control
Wind direction and velocity variations create the need for flightpath corrections during a ground reference maneuver. In a similar way
that water currents affect the progress of a boat or ship, wind directly influences the path that the airplane travels in reference to the
ground. Whenever the airplane is in flight, the movement of the air directly affects the actual ground track of the airplane.
For example, an airplane is traveling at 90 knots (90 nautical miles per hour) and the wind is blowing from right to left at 10 knots.
The airplane continues forward at 90 knots but also travels left 10 nautical miles for every hour of flight time. If the airplane, in this
example doubles its speed to 180 knots, it still drifts laterally to the left 10 nautical miles every hour. Unless in still air, traveling to a
point on the surface requires compensation for the movement of the air mass.
Ground reference maneuvers are generally flown at altitudes between 600 and 1,000 feet above ground level (AGL). The pilot should
consider the following when selecting the maneuvering altitude:
⦁ The lower the maneuvering altitude, the faster the airplane appears to travel in relation to the ground.
⦁ Drift should be easily recognizable from both sides of the airplane.
⦁ The altitude should provide obstruction clearance of no less than 500 feet vertically above the obstruction
an
d 2,000 feet horizontally.
⦁ In the event of an engine failure, lower altitudes equate to less time to configure the airplane and reduced
liding distance before a forced landing.
⦁ What specific altitude or altitude range does the testing standard call for?
Correcting Drift During Straight-and-Level Flight
When flying straight and level and following a selected straight-line direct ground track, the preferred method of correcting for wind
drift is to angle the airplane sufficiently into the wind to cancel the effect of the sideways drift caused by the wind. The wind’s speed,
the angle between the wind direction and the airplane’s longitudinal axis, and the airspeed of the airplane determine the required wind
correction angle. For example, an airplane with an airspeed of 100 knots in an air mass moving at 20 knots directly from the side,
should turn 12° into the wind to cancel the airplane's drift. If the wind in the above example is only 10 knots, the wind correction
angle required to cancel the drift is six degrees. When the drift has been neutralized by heading the airplane into the wind, the
airplane will fly the direct straight ground track.
To further illustrate this point, if a boat is crossing a river and the river’s current is completely still, the boat could head directly to a
point on the opposite shore on a straight course without any drift. However, rivers tend to have a downstream current that needs to be
considered if the captain wants the boat to arrive at the opposite shore using a direct straight path. Any downstream current pushes the
boat sideways and downstream at the speed of the current. To counteract this downstream movement, the boat needs to move
upstream at the same speed as the river is moving the boat downstream. This is accomplished by angling the boat upstream to
counteract the downstream flow. If done correctly, the boat follows a direct straight track across the river to the intended destination
point. A slower forward speed of the boat or a faster river current requires a greater angle to counteract the drift. [Figure 7-1]
Figure 7-1. Wind drift.
As soon as the pilot lifts off the surface and levels the wings in a crosswind, the airplane begins tracking sideways. The force of the
crosswind acts on the mass of the airplane, and the speed of drift increases up to the speed of the crosswind component. A wind that is
directly to the right or the left (at a 90° angle) will cause the airplane to accelerate sideways at the same speed as the wind. When the
wind is halfway between the side and the nose of the airplane (at a 45° angle), it causes a sideways drift up to just over 70 percent of
the total speed of the wind. It should be understood that pilots do not calculate the required drift correction angles for ground
reference maneuvers; they merely use the references and adjust the airplane’s relationship to those references to cancel any drift. The
groundspeed of the airplane is also affected by the wind. As the wind direction becomes parallel to the airplane’s longitudinal axis,
the magnitude of the wind’s effect on the groundspeed is greater; as the wind becomes perpendicular to the longitudinal axis, the
magnitude of the wind’s effect on the groundspeed is less. In general, When the wind is blowing straight into the nose of the airplane,
the groundspeed will be less than the airspeed. When the wind is blowing from directly behind the airplane, the groundspeed will be
faster than the airspeed. In other words, when the airplane is headed upwind, the groundspeed is decreased; when headed downwind,
the groundspeed is increased.
Constant Radius During Turning Flight
In a no-wind condition, a pilot may make a constant-radius turn over the ground using a fixed bank angle. If wind is present, however,
a pilot will observe a change in the radius of a turn while maintaining that same constant bank angle. [Figure 7-2] As groundspeed
increases, the observed radius of the turn increases. Conversely, as groundspeed decreases, the radius of the turn over the ground will
decrease. For a ground-referenced constant-radius turn, the pilot compensates for changes in groundspeed by varying the bank angle
throughout the turn. When groundspeed increases, the pilot banks more steeply to maintain a constant-radius turn over the ground.
The converse is also true: when groundspeed decreases, the pilot uses a shallower bank.
Figure 7-2. Effect of wind during a turn.
For a given true airspeed, the radius of turn in the air varies proportionally with the bank angle. To maintain a constant radius over the
ground, the bank angle used is proportional to groundspeed. For example, an airplane is in the downwind position at 100 knots
groundspeed. In this example, the wind is 10 knots, meaning that the airplane has an airspeed of 90 knots (for this discussion, assume
true, calibrated, and indicated airspeed are all the same). If the pilot starts a turn using a 45° bank angle, the turn radius over the
ground at that moment is approximately 890 feet. As the airplane turns, the groundspeed decreases and the bank angle needs to be
reduced in order to maintain the same turn radius of 890 feet over the ground. At the upwind point of the turn, the bank angle should
be approximately 33°. In another example, if the downwind is flown at an airspeed of 90 knots in a 10 knot tailwind with a desired
turn radius of 2,000 feet, the bank angle would be approximately 24°. The bank angle flying upwind would be approximately 16°.
Put another way, at a higher groundspeed, there is less time to turn the airplane while trying to maintain a ground-referenced constant-
radius turn. The pilot increases the bank angle in order to increase the rate of turn, and the increased rate of turn offsets the reduced
time available to make the turn. Conversely, when flying at a lower groundspeed, the pilot reduces the angle of bank and rate of turn
to compensate for the additional time taken while making the turn. With some experience, pilots may notice how wind direction
affects the time needed for various segments of ground-referenced turns.
To demonstrate the effect that wind has on turns, the pilot should select a straight-line ground reference, such as a road or railroad
track. [Figure 7-3] Choosing a straight-line ground reference that is parallel to the wind, the airplane would be flown into the wind
and directly over the selected straight-line ground reference. Once a straight-line ground reference is established, the pilot makes a
360° constant medium-banked turn. As the airplane completes the 360° turn, it should return directly over the straight-line ground
reference but downwind from the starting point. Choosing a straight-line ground reference that has a crosswind, and using the same
360° constant medium-banked turn, demonstrates how the airplane drifts away from the reference even as the pilot holds a constant
bank angle. In both examples, the path over the ground is not circular, although in reference to the air, the airplane flew a perfect
continuous radius.
Figure 7-3. Effect of wind during turn.
In order to compensate for the effects of wind drift, the pilot adjusts the bank angle as the groundspeed changes throughout the turn.
Where groundspeed is the fastest, such as when the airplane is headed downwind, the bank angle should be steepest. Where
groundspeed is the slowest, such as when the airplane is headed upwind, the bank angle should be shallow. It is necessary to increase
or decrease the angle of bank, which increases or decreases the rate of turn, to achieve the desired constant radius track over the
ground.
Ground reference maneuvers should always be entered from a downwind position. This allows the pilot to establish the steepest bank
angle required to maintain a constant radius ground track. If the bank is too steep, the pilot should immediately exit the maneuver and
re-establish a lateral position that is further from the ground reference. The pilot should avoid bank angles in excess of 45°due to the
increased stalling speed.
Tracking Over and Parallel to a Straight Line
The pilot should first be introduced to ground reference maneuvers by correcting for the effects of a crosswind over a straig ht-line
ground reference, such as road or railroad tracks. If a straight road or railroad track is unavailable, the pilot should choose multiple
references (three minimum) which line up along a straight path. The reference line should be suitably long so the pilot has sufficient
time to understand the concepts of wind correction and practice the maneuver. Initially, the maneuver should be flown directly over
the ground reference line with the pilot angling the airplane’s longitudinal axis into the wind sufficiently such as to cancel the effect
of drift. The pilot should scan between far ahead and close to the airplane to practice tracking multiple references.
When proficiency has been demonstrated by flying directly over the ground reference line, the pilot should then practice flying a
straight parallel path that is offset from the ground reference. The offset parallel path should not be more than three-fourths of a mile
from the reference line. The maneuver should be flown offset from the ground references with the pilot angling the airplane’s
longitudinal axis into the wind sufficiently to cancel the effect of drift while maintaining a parallel track.
Rectangular Course
A principal ground reference maneuver is the rectangular course. [Figure 7-4] The rectangular course is a training maneuver in which
the airplane maintains an equal distance from all sides of the selected rectangular references. The maneuver is accomplished to
replicate the airport traffic pattern that an airplane typically maneuvers while landing. While performing the rectangular course
maneuver, the pilot should maintain a constant altitude, airspeed, and distance from the ground references. The maneuver assists the
pilot in practicing the following:
⦁ Maintaining a specific relationship between the airplane and the ground.
⦁ Dividing attention between the flightpath, ground-based references, manipulating the flight controls, and
scanning for outside hazards and instrument indications.
⦁ Adjusting the bank angle during turns to correct for groundspeed changes in order to maintain constant-
adius turns.
⦁ Rolling out from a turn with the required wind correction angle to compensate for any drift caused by the
ind.
⦁ Establishing and correcting the wind correction angle in order to maintain the track over the ground.
⦁ Preparing the pilot for the airport traffic pattern and subsequent landing pattern practice.
To fly the rectangular course, the pilot should first locate a square field, a rectangular field, or an area with suitable ground references
on all four sides. Note that a square meets the definition of a rectangle. As previously mentioned, this area should be selected
consistent with safe practices. The airplane should be flown parallel to and at an equal distance between one-half to three-fourths of a
mile away from the field boundaries or selected ground references. The flightpath should be positioned outside the field boundaries or
selected ground references so that the references may be easily observed from either pilot seat. It is not practical to fly directly above
the field boundaries or selected ground references. The pilot should avoid flying close to the references, as this will require the pilot
to turn using very steep bank angles, thereby increasing aerodynamic load factor and the airplane’s stall speed, especially in the
downwind to crosswind turn.
Figure 7-4. Rectangular course.
The entry into the maneuver should be accomplished downwind. This places the wind on the tail of the airplane and results in an
increased groundspeed. There should be no wind correction angle if the wind is directly on the tail of the airplane; however, a real-
world situation often results in some drift correction. The turn from the downwind leg onto the base leg is entered with a relatively
steep bank angle. The pilot should roll the airplane into a steep bank with rapid, but not excessive, coordinated aileron and rudder
pressures. As the airplane turns onto the following base leg, the tailwind lessens and becomes a crosswind; the bank angle is reduced
gradually with coordinated aileron and rudder pressures. The pilot should be prepared for the lateral drift and compensate by turning
more than 90° angling toward the inside of the rectangular course.
The next leg is where the airplane turns from a base leg position to the upwind leg. Ideally, on the upwind, the wind is directly on the
nose of the airplane resulting in a direct headwind and decreased groundspeed; however, some drift correction may be necessary. The
pilot should roll the airplane into a medium-banked turn with coordinated aileron and rudder pressures. As the airplane turns onto the
upwind leg, the crosswind lessens and becomes a headwind, and the bank angle is gradually reduced with coordinated aileron an d
rudder pressures. Because the pilot was angled into the wind on the base leg, the turn to the upwind leg is less than 90°.
The next leg is where the airplane turns from an upwind leg position to the crosswind leg. The pilot should slowly roll the airplane
into a shallow-banked turn, as the developing crosswind drifts the airplane into the inside of the rectangular course with coordinated
aileron and rudder pressures. As the airplane turns onto the crosswind leg, the headwind lessens and becomes a crosswind. As the turn
nears completion, the bank angle is reduced with coordinated aileron and rudder pressures. To compensate for the crosswind, the
pilot maintains an angle into the wind, toward the outside of the rectangular course, which requires the turn to be less than 90°.
The final turn is back to the downwind leg, which requires a medium-banked angle and a turn greater than 90°. The groundspeed will
be increasing as the turn progresses and the bank should be held and then rolled out in a rapid, but not excessive, manner using
coordinated aileron and rudder pressures.